It's basically impossible to hold your breath until you suffocate, or even until you pass out. But what's going on in your body to prevent that from happening? Why can't you suffocate by holding your breath?

There are multiple systems keeping you from holding your breath too long, each of which would take over if another failed — and that's a very good thing.

Several brain regions work to keep you breathing.

"The first one is your motor cortex … and that's sensing that you're not breathing," Anthony Bain, an associate professor in the Department of Kinesiology at the University of Windsor in Canada, told Live Science. "So that sends signals down to your breathing center, which is the base of the brain, the medulla." That controls the muscles that help you breathe, like the diaphragm, the main muscle responsible for inflating and deflating the lungs, and the intercostal muscles, which are located between the ribs and help to expand the chest with each breath.

Related: Why don't we breathe equally out of both nostrils?

The second region is a network farther down in the brainstem called the pre-Bötzinger complex, which acts as the body's respiratory rhythm generator.

"That is continually going, even when you're holding your breath," Bain said. "It's kind of like a heart rate." That is, even when you're not breathing, this respiratory pacemaker is still ticking away, trying to make you breathe.

In addition, groups of cells called chemoreceptors keep track of the levels of oxygen and carbon dioxide in the body. There are two sets of these cells: the central chemoreceptors and the peripheral chemoreflex.

The central chemoreceptors, located in the brain, "primarily just respond to carbon dioxide," Bain said. The peripheral chemoreflex is located in the neck, near the larynx. These cells "will respond to both carbon dioxide and then low levels of oxygen when you extend that breath hold for a prolonged period of time," Bain said.

Finally, there are receptors in the lungs that detect the stretch that happens when they inflate and deflate. When you hold your breath and they stop stretching, alarm bells start to sound.

When any one of these systems detects that something's wrong, it sends stress signals to the respiratory center in the brain, which does everything it can to restart the breathing process.

In studies, researchers have found ways to disable some of these systems to see how it affects the length of time participants can hold their breath. In one study, heart-lung transplant recipients whose lung receptors weren't fully connected to the central nervous system couldn't hold their breath any longer than normal participants, showing that those stretch receptors in the lungs aren't strictly necessary to keep you breathing.

Chemoreceptors seem to play a bigger role. In a different study, Bain and his team used dopamine to inhibit the carotid body, which is part of the peripheral chemoreflex — the group of cells that sense oxygen and carbon dioxide levels.

"If you do that in normal people holding their breath … then you are able to extend the breath hold time," Bain said.

Elite divers are different: through training, they can hold their breath much longer than regular people. The record for static apnea — holding your breath underwater without using oxygen during preparation — is just under 12 minutes. For these divers, inhibiting the carotid body doesn't do much. "It doesn't actually extend their breath hold time, because now the mechanisms for when they actually break are actually quite separate from a nonelite breath holder," Bain said.

In fact, elite divers prove that with enough training, it's actually possible to hold your breath until you pass out. They've trained to push past the signals sent by their chemoreceptors and get their oxygen levels much lower than an untrained person, breathing only when they sense they're about to fall unconscious. "It's that critical level of hypoxia that they have to sense, and then they start breathing again," Bain said.

One intervention that has a huge effect on breath-hold time in untrained people is paralysis of the diaphragm, the muscle that brings air into and out of the lungs. In the 1970s, scientists injected anesthetic into the phrenic nerves, which send signals from the motor cortex to the diaphragm, and found that it doubled the time participants could hold their breath. But it still didn't allow them to hold their breath until they passed out, which shows the importance of training.

Finally, one way for both trained and untrained people to extend their breath-holding time is by bringing more oxygen into their system, either by hyperventilating normally or inhaling pure oxygen. In fact, this is sometimes used in medical scans where patients need to stay still for long periods of time.

"You can give them 100% oxygen and then they can hold their breath for, you know, up to five minutes, in some cases," Bain said.

This is how the Guinness World Record for breath holding was set. In 2021, Budimir Šobat, a Croatian free diver, held his breath for 24 minutes, 37 seconds.

Extra oxygen tells those peripheral chemoreceptors that everything is fine. But even if they were disabled, the body has enough fail-safes to keep you breathing before you pass out.

"It just makes sense from an evolutionary perspective," Bain said. "Breathing is so important. It makes sense to have a redundancy in systems to tell the body to keep breathing."

Scientists have discovered a brand-new type of cell hiding inside the delicate, branching passageways of human lungs. The newfound cells play a vital role in keeping the respiratory system functioning properly and could even inspire new treatments to reverse the effects of certain smoking-related diseases, according to a new study. 

The cells, known as respiratory airway secretory (RAS) cells, are found in tiny, branching passages known as bronchioles, which are tipped with alveoli, the teensy air sacs that exchange oxygen and carbon dioxide with the bloodstream. The new RAS cells are similar to stem cells — "blank canvas" cells that can differentiate into any other type of cell in the body — and are capable of repairing damaged alveoli cells and transforming into new ones. 

Researchers discovered the RAS cells after becoming increasingly frustrated by the limitations of relying on the lungs of mice as models for the human respiratory system. However, because of certain differences between the two, scientists have struggled to fill some knowledge gaps about human lungs. To get a better understanding of these differences on a cellular level, the team took lung tissue samples from healthy human donors and analyzed the genes within individual cells, which revealed the previously unknown RAS cells.

"It has been known for some time that the airways of the human lung are different than in the mouse," senior author Edward Morrisey, a professor at the Perelman School of Medicine at the University of Pennsylvania who specializes in respiratory systems, told Live Science. "But emerging technologies have only recently allowed us to sample and identify unique cell types."

Related: 10 strangest medical cases of 2021 

The team also found RAS cells in ferrets, whose respiratory systems are more similar to humans' than those of mice are. As a result, the researchers suspect that most mammals equal or larger in size are likely to have RAS cells in their lungs, Morrisey said.

RAS cells serve two main functions in the lungs. First, they secrete molecules that  maintain the fluid lining along bronchioles, helping to prevent the tiny airways from collapsing and maximizing the efficiency of the lungs. Second, they can act as progenitor cells for alveolar type 2 (AT2) cells, a special type of alveoli that secrete a chemical that is used in part to repair other damaged alveoli. (A progenitor cell is a cell that has the capacity to differentiate into another type of cell, similar to how stem cells differentiate into other cells.) 

"RAS cells are what we've termed facultative progenitors," Morrisey said, "which means they act as both progenitor cells and also have important functional roles in maintaining airway health." This means RAS cells play a vital role in maintaining healthy lungs, he added.

The researchers think RAS cells may play a key role in smoking-related diseases, such as chronic obstructive pulmonary disease (COPD). COPD is the result of inflammation of airway passages inside the lungs, which can be caused by smoking and, occasionally, air pollution, according to the Mayo Clinic. The inflammation of the airways makes it harder for the lungs to properly take in enough oxygen; as a result, COPD has similar symptoms to asthma. COPD can also lead to emphysema, in which alveoli are permanently destroyed, and chronic bronchitis, a long-lasting and intense cough usually accompanied by excess phlegm. Every year, more than 3 million people around the world die from COPD, according to the World Health Organization.

In theory, RAS cells should prevent, or at least alleviate, the effects of COPD by repairing damaged alveoli. However, the researchers suspect that smoking can damage, or even completely destroy, the new cells, leading to the onset of diseases such as COPD.

Patients who have COPD are often prescribed anti-inflammatory drugs or oxygen therapy to ease their symptoms. However, these are only temporary solutions and do nothing to reverse lung damage. RAS cells could potentially be used to improve treatments or even cure COPD, if researchers can properly harness these cells' regenerative properties.

"We really don't know if this discovery could lead to a potential cure for COPD yet," Morrisey said. "However, since COPD is a disease we know very little about, any new insight should help the field start to think about new therapeutic approaches that could lead to better treatments."

The study was published online March 30 in the journal Nature.

Originally published on Live Science.

The human body is a complex network of systems that work together to keep life-sustaining processes running smoothly. These systems break down food for fuel, clear away waste, repair damaged tissues and DNA, fight infectious germs and monitor the outside world so we can move through it safely. 

Many scientists spend their days working to understand how each bodily system performs its jobs, how the systems interact, and what can happen when one or more of them falter. Such malfunctions can stem from aging or disease, for instance, and through medical care, doctors aim to get derailed systems back on track. 

Here's a quick rundown of the systems of the human body, its vital organs and its "vestigial" organs, as well as a few fascinating facts about how the body works.

What are the different systems of the human body? 

Our bodies consist of a number of biological systems that carry out specific functions necessary for everyday living. Some organs and tissues play roles in multiple systems at once.

Related: Strange, two-faced brain cells confirmed to exist, and they may play a role in schizophrenia 

Circulatory: The job of the circulatory system is to move blood, nutrients, oxygen, carbon dioxide and hormones around the body. It consists of the heart, blood, blood vessels, arteries and veins. According to the Cleveland Clinic, the adult human body's network of blood vessels is more than 60,000 miles (around 100,000 kilometers) long. 

Digestive: The digestive system consists of a series of connected organs that together allow the body to break down and absorb nutrients from food and remove waste. It includes the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. The large intestine is home to microorganisms that are collectively called the gut microbiome and influence our health in various ways. The liver and pancreas also have roles in the digestive system because they produce digestive juices filled with enzymes to break down the components of food, such as carbohydrates, fats and proteins, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Endocrine: The endocrine system consists of a network of glands that secrete hormones — long-range chemical messengers that regulate how cells and tissue function — into the blood. These hormones, in turn, travel to different tissues and regulate many bodily functions, such as metabolism, growth and sexual function, according to Johns Hopkins Medicine. For example, the pancreas releases the hormones insulin and glucagon to regulate blood sugar. Conditions like diabetes and insulin resistance arise from the body having too little insulin or not responding to it adequately. 

Related: Meet the 'exclusome': A mini-organ just discovered in cells that defends the genome from attack

Immune: The immune system is the body's defense against bacteria, viruses and other pathogens that may be harmful. Components of the system include the lymph nodes, which contain infection-fighting cells called lymphocytes. These lymphocytes are one of many types of leukocyte, or white blood cell. The immune system also includes the spleen, the bone marrow and a gland called the thymus. The immune system can learn to recognize antigens — proteins on the surface of bacteria, fungi and viruses — and alert the body to their presence. Some immune cells make proteins called antibodies that attach to these antigens and mark invaders for destruction. 

Lymphatic: The lymphatic system includes the lymph nodes, lymph ducts and lymph vessels and is considered part of the immune system. Its main job is to make and move lymph, a clear fluid that contains white blood cells. The lymphatic system also removes excess lymph fluid from the body's tissues and returns it to the blood.

Nervous: The nervous system controls both voluntary actions, such as conscious movements, and involuntary actions,like breathing, and it sends signals to and detects signals from different parts of the body. Conscious actions are controlled by the somatic nervous system, while involuntary actions are controlled by the autonomic nervous system. The autonomic nervous system dictates whether we're in "rest and digest" or "fight or flight" mode. The nervous system can further be split up into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system, or the nerves connecting the CNS to every other part of the body.

Muscular: The body's muscular system consists of hundreds of muscles that aid movement, blood flow and other bodily functions, according to the Library of Congress. There are three types of muscle: skeletal, which is connected to bone and helps with voluntary movement; smooth, which is found inside organs and helps to move substances through them; and cardiac, which is found in the heart. The body's largest muscle by mass is the gluteus maximus, but the two latissimus dorsi are the largest in terms of surface area.

Related: Why is it harder for some people to build muscle than others?

Reproductive: The reproductive system allows humans to produce offspring. The male reproductive system includes the penis and the testes, which produce sperm. The female reproductive system includes the vagina, uterus and ovaries, which produce eggs. During fertilization, a sperm cell will fuse with an egg cell that, in a successful pregnancy, will then implant in the uterus. The fertilized egg will then mature into what's called a blastocyst, then an embryo and, finally, a fetus. A placenta forms to support this process. 

Skeletal: Our bodies are supported by the skeletal system, which contains between 206 and 213 bones in an adult human body, due to slight variations in people's anatomy, according to the medical resource StatPearls. These bones are connected by tissues called tendons, ligaments and cartilage. As infants, humans have about 300 bones, but some fuse together as the child grows. The skeleton not only helps us move but is  also involved in the production of blood cells and the storage of calcium. The teeth are also part of the skeletal system, but they aren't considered bones. The smallest bones in the body are found in the ear, and the largest is the femur, or thigh bone, which is also one of the heaviest body parts.

Respiratory: The respiratory system allows us to take in oxygen and expel carbon dioxide through breathing. It includes the lungs; trachea, or windpipe; and the diaphragm, a muscle that pulls air into and pushes air out of the lungs.

Urinary: The urinary system helps eliminate a waste product called urea, which is produced when certain foods are broken down. The system includes the two kidneys; two ureters, or tubes leaving the kidneys; the bladder; two sphincter muscles; and the urethra. The kidneys filter blood in the body to make urine that then travels down the ureters to the bladder and exits the body through the urethra.

Integumentary: The skin, hair and nails make up the integumentary system. Skin is the body's largest organ. It protects our innards from the outside world, serving as our first defense against bacteria, viruses and other pathogens, for instance. Our skin also helps regulate body temperature and eliminate waste through perspiration, or sweat. 

Related: Scientists discover new way humans feel touch 

What are the body's vital organs?

Click the purple circles to learn about the body's vital organs, including the brain, lungs, heart, liver and kidneys. They're considered vital because you need a functioning brain, heart, liver, at least one kidney and at least one lung to survive. That said, there are medical devices and treatments that can make up for a loss of function in these organs, at least temporarily — for example, ECMO machines can do the work of the heart and lungs, and dialysis can filter the blood of people with kidney failure.

Fast facts

• The average adult male body contains about 36 trillion cells, the average adult female body contains 28 trillion cells and a 10-year-old has about 17 trillion. 
• It's often said that there are 78 organs in the human body, but the number actually differs depending on whom you ask. 
• There's a popular idea that the body replaces itself every seven years. But that's not really true, because tissues renew themselves at different rates. 
• Oxygen is the most common element in the human body, followed by carbon. 
• The average adult body contains about 1.2 to 1.5 gallons (4.5 to 5.5 liters) of blood. 
• Humans' average body temperature has fallen slightly over time, so it's no longer 98.6 degrees Fahrenheit (37 degrees Celsius). 
• The most detailed map of the human brain to date contains more than 3,300 types of brain cells. 

What are vestigial organs?

There are arguably some parts of the human body that don't serve any useful purpose, such as the male nipple. That said, the usefulness of some organs is still up for debate, as scientists have often judged the worth of body parts before discovering their purposes. 

Broadly speaking, vestigial body parts are defined as those that have lost their original physiological significance to humans over the course of evolutionary history. The idea is that, while we inherited them from an ancient ancestor, we could really do without them in the modern day. 

Wisdom teeth are held up as one example of a vestigial body part, as the modern human jaw is often too small to accommodate a third set of molars. Some people also carry remnants of a vomeronasal organ that is largely thought to be nonfunctional in humans; animals use equivalent organs to detect each other's pheromones. 

Some scientists consider the human tailbone, or coccyx, vestigial because it's no longer a full-blown tail. But it's far from useless, as it still anchors many muscles, ligaments and tendons. And the appendix has gotten a bad rap for supposedly being both vestigial and useless, but more recently, scientists have uncovered possible functions for the long-maligned body part. 

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Editor's note: This page was last updated on April 5, 2024.

The human respiratory system is a network of organs responsible for taking in oxygen and expelling carbon dioxide. Its primary organs are the lungs, which carry out this exchange of gases as we breathe. 

The lungs work with the circulatory system to pump oxygen-rich blood to all cells in the body. The blood then collects carbon dioxide and other waste products and transports them back to the lungs, where the waste products are pumped out of the body when we exhale, according to the American Lung Association.

The human body needs oxygen to sustain itself. After only about five minutes without oxygen, brain cells begin dying, according to the National Institute of Neurological Disorders and Stroke, which can lead to brain damage and ultimately death. 

Related: Gasp! 11 surprising facts about the respiratory system

In humans, the average breathing, or respiratory rate, mostly depends on age. A newborn's normal breathing rate is about 40 to 60 times each minute and may slow to 30 to 40 times per minute when the baby is sleeping, according to Stanford Children's Health. The average resting respiratory rate for adults is 12 to 16 breaths per minute, and up to 40 to 60 breaths per minute during exercise, according to the European Respiratory Society.

Parts of the respiratory system

There are many components to the respiratory system. They include:

• Nose 
• Mouth 
• Throat (pharynx) 
• Voice box (larynx) 
• Windpipe (trachea) 
• Large airways (bronchi) 
• Small airways (bronchioles) 
• Lungs
• Diaphragm

As we breathe, oxygen enters the nose or mouth and passes the sinuses, which are hollow spaces in the skull that help regulate the temperature and humidity of the air we breathe. 

From the sinuses, air passes through the trachea, also called the windpipe, and into the bronchial tubes, which are the two tubes that carry air into each lung (each one is called a bronchus). The bronchial tubes are lined with tiny hairs called cilia that move back and forth, carrying mucus up and out. Mucus is a sticky fluid that collects dust, germs and other matter that has invaded the lungs and is what we expel when we sneeze and cough. 

Related: Where does all my snot come from? 

The bronchial tubes split up again to carry air into the lobes of each lung. The right lung has three lobes while the left lung has only two, to accommodate room for the heart, according to the American Lung Association. The lobes are filled with small, spongy sacs called alveoli, which is where the exchange of oxygen and carbon dioxide occurs. 

The alveolar walls are extremely thin (about 0.2 micrometers) and are composed of a single layer of tissues called epithelial cells and tiny blood vessels called pulmonary capillaries. Blood in the capillaries picks up oxygen and drops off carbon dioxide. The oxygenated blood then makes its way to the pulmonary veins. These four veins, two from each lung, carry oxygen-rich blood to the left side of the heart, where it is pumped to all parts of the body. The carbon dioxide the blood left behind moves into the alveoli and gets expelled in our exhaled breath.

The diaphragm, a dome-shaped muscle at the bottom of the lungs, controls breathing and separates the chest cavity from the abdominal cavity. When air gets taken in, the diaphragm tightens and moves downward, making more space for the lungs to fill with air and expand, according to the National Heart, Lung and Blood Institute. During exhalation, the diaphragm expands and compresses the lungs, forcing air out.

Respiratory system diseases

Diseases and conditions of the respiratory system fall into two categories: Infections, such as influenza, bacterial pneumonia and enterovirus respiratory virus, and chronic diseases, such as asthma and chronic obstructive pulmonary disease (COPD). 

Viral infections

Not much can be done for viral infections but to let them run their course, according to Dr. Neal Chaisson, who practices pulmonary medicine at the Cleveland Clinic. "Antibiotics are not effective in treating viruses and the best thing to do is just rest," he said. 

For most healthy individuals, the most common respiratory ailment they may face is an infection, said Dr. Matthew Exline, a pulmonologist and critical care expert at The Ohio State University Wexner Medical Center. A cough is the first symptom, possibly accompanied by a fever. 

Related:The gross science of a cough and a sneeze

"However, a cough can be a sign of chronic respiratory conditions such as asthma, chronic bronchitis or emphysema," he said. "In chronic lung disease, most respiratory diseases present with shortness of breath, initially with exertion, such as walking a significant distance or climbing several flights of stairs."

Asthma

Asthma is a chronic inflammation of the lung airways that causes coughing, wheezing, chest tightness or shortness of breath, according to Tonya Winders, president of the Allergy & Asthma Network. These signs and symptoms may be worse when a person is exposed to their triggers, which can include air pollution, tobacco smoke, factory fumes, cleaning solvents, infections, pollens, foods, cold air, exercise, chemicals and medications. Exercise can also induce asthma. More than 25 million people (or 1 in 13 adults and 1 in 12 children) in the United States have asthma, according to the Centers for Disease Control and Prevention (CDC).

For some people, asthma is a mild irritation, but for others it can be a life-threatening condition, according to the Mayo Clinic. Asthma cannot be cured, but its symptoms can be managed. Early identification and treatment can prevent long-term damage and stop asthma from getting worse over time.

Chronic obstructive pulmonary disease (COPD)

COPD is a chronic and progressive disease in which the air flow in and out of the lungs decreases, making it harder to breathe. COPD is a combination of chronic bronchitis (inflammation of the bronchial tubes) and emphysema (damaged alveoli), according to the Mayo Clinic. Smoking is the leading cause of COPD. 

Over time, the airways of people with COPD become inflamed and thicken, making it harder to get rid of waste carbon dioxide, according to the American Lung Association. As the disease progresses, patients experience a shortness of breath, and it can limit activity. More than 16 million Americans are affected by COPD, according to the CDC. COPD has no cure, but it can be treated.

Lung cancer 

Lung cancer is often associated with smoking, but the disease can affect nonsmokers as well. It is the second most common cancer for both men and women, outranked by prostate and breast cancers, respectively. 

The American Cancer Society (ACS) estimates that in 2021, there will be about 235,760 new cases of lung cancer (119,100 in men and 116,660 in women) and around 131,880 deaths from lung cancer (69,410 in men and 62,470 in women) in the United States. However, the number of lung cancer deaths has been on a downward slope in recent years due to advances in treatment and early detection.Most people diagnosed with lung cancer are older than 65, and the average age of people diagnosed with lung cancer is 70, according to ACS. 

There are two different types of lung cancer, which is cancer that originates in the lungs as opposed to cancer that spreads to the lungs –– small cell lung cancer and non-small cell lung cancer, according to the Mayo Clinic. Small cell lung cancer is most commonly found in heavy smokers, and is less common than non-small cell lung cancer. 

The main symptoms for lung cancer are shortness of breath, pain, coughing up blood, and fluid in the lungs. A doctor diagnoses lung cancer by performing imaging tests, such as a CT scan; testing coughed-up sputum; and a lung biopsy.

Treatment is based on the extent of the lung cancer, and whether it has spread to other parts of the body. Treatments range from surgery, chemotherapy and radiation therapy, through to palliative care.

Additional resources

• Read more about the anatomy of the respiratory system from the University of Rochester Medical Center. 
• Watch "Meet the Lungs," from the Khan Academy. 
• Check out this useful diagram of the respiratory system, from The Lung Association. 

This article was updated on July 16, 2021 by Live Science Contributor Sarah Wild.

A bout of influenza may have a long-lasting side effect: The growth of bizarrely out-of-place taste bud cells in the lungs.

New research conducted in mice finds that the growth of these taste bud cells may be linked to long-term problems with lung function after the flu, though additional research is needed to confirm the findings in humans.

Still, taste bud cells in the lungs "was just really weird to see, because the cells are not in the lung" normally, study author Andrew Vaughan, a biologist at the University of Pennsylvania's School of Veterinary Medicine, said in a statement. "The closest they are normally [found] is in the trachea." [11 Surprising Facts About the Respiratory System]

Rebuilding after the flu

Vaughan and his colleagues were studying the long-lasting impacts of severe lung inflammation caused by influenza A, one of the flu virus types responsible for the viral infection that circulates every winter. Around half a million people worldwide die from influenza A each year, Vaughan and his colleagues wrote in a paper published March 25 in the American Journal of Physiology – Lung, Cellular and Molecular Physiology. Many people who recover have long-lasting problems with lung function.

The researchers had previously found that this loss of lung function is likely related to the way the lungs rebuild themselves after sustaining severe damage from the infection. Certain cells called lineage-negative epithelial progenitors vastly expand their numbers in the lungs after the virus clears. They seem to help rebuild tissue, but many morph into abnormal cell types that can't do the typical job of exchanging oxygen and carbon dioxide across lung tissue.

In the new study, the researchers infected mice with H1N1, a type of influenza A. Then, the researchers euthanized the mice at different points during their recovery to study how their lung tissue had changed over time.

Out of place

They were unsurprised to find, post-infection, that the lungs were a hotspot of immune activity. What was odd, though, was that there was a strong "Type 2" immune response, which involves particular immune cells known to respond strongly to parasitic worms and to be involved in allergies — neither of which is involved with the flu.

The researchers were perplexed by what might be creating this persistent immune response, so they set out looking for a particular type of cell known to cause it. These cells, called tuft cells, brush cells or solitary chemosensory cells, shouldn't be in the lungs. But in the post-flu mice, they were everywhere.

The cells are of the same sort found in taste buds, and they detect bitterness. When the researchers stimulated the out-of-place cells with bitter compounds, they went wild, growing and triggering an inflammatory response. The researchers also found that the out-of-place taste bud cells arose from the same lineage-negative epithelial progenitors already known to rebuild nonfunctional lung tissue after the flu.

This finding was exciting, Vaughan said, because solitary chemosensory cells are present in elevated numbers in people with asthma and in nasal polyps, which are noncancerous tissue growths in the nasal passage linked to inflammation.

"These recent findings may be a link between Type 2 inflammatory diseases, such as asthma, as well as nasal polyps, following a respiratory viral infection," Vaughan said in the statement. The finding could explain why children who get severe respiratory infections are predisposed to asthma later, he added. The researchers now plan to examine human lung samples to confirm that the same cells appear after the flu.

• 11 Surprising Facts About the Immune System
• 6 Flu Vaccine Myths
• The 9 Deadliest Viruses on Earth

Originally published on Live Science.

A man in China had a habit of walking home from work every day, taking off his socks and… taking a great big whiff of them, according to news reports.

Bizarre? Yes. But harmful? Well, according to a video posted on the Chinese platform Pear Daily, also yes. The video says that the 37-year-old man was hospitalized for chest pain, and was diagnosed with a fungal infection in his lungs — an infection that his doctors attributed to fungal spores that he had inhaled from his socks.

But is it even possible to get an infection like this from smelling socks?

Technically, yes — but it's very unlikely that something like this would happen, said Dr. William Schaffner, an infectious-disease specialist at Vanderbilt University who was not involved with the Chinese man's case. Indeed, Schaffner noted that in his "long clinical experience," he'd never heard of a case like this. The case is "very interesting, if true," he added. [27 Oddest Medical Case Reports]

However, the lack of details about the case in local news reports, such as what kind of fungus caused the infection, makes Schaffner "kind of dubious to start with,” he said.

Biologically, it's possible for someone to develop a lung infection by inhaling fungal spores that had built up heavily in someone's socks, Schaffner told Live Science.

Indeed, lung infections from inhaling fungal spores are well-documented. Cave explorers, for example, run the risk of an infection called histoplasmosis, which is caused by inhaling fungal spores that can be found in bat droppings. And inhaling coccidioides fungal spores — which are found throughout the western and southwestern United States — can cause a flu-like infection called valley fever.

"We don’t live in a sterile world, we're surrounded by bacteria and fungi all the time," Schaffner said. That doesn't mean we're definitely going to get sick, though. What makes the Chinese man's case different, though, is that he's said to have "put the source [of fungus] right up to his nose and inhaled quite frequently, in unusually large doses and repeated doses, [which would have] made him more susceptible to actually developing an illness,” he said.

There's also not much known about the patient himself, based on the available reporting. For example, the man could have had a weakened immune system that would've made him more susceptible to such an infection, Schaffner said. The man's doctor said in local news reports that the man likely did have a weaker immune system, and this was due to a lack of rest because he was looking after a child.

But Schaffner said that he found that explanation "rather thin." That's not typically a reason doctors would consider a patient to be immune-suppressed, he said, "so [when] I saw that, I raised my eyebrows."

In any case, the whole situation "reinforces the notion that one ought to launder ones socks frequently rather than trying to make a daily assessment as to whether you want to put them on again for the seventeeth time," Schaffner added.

Still, the occasional sock-smeller — you know, the person who grabs a sock for a quick is-this-clean check before getting dressed — can rest easy, and need not fear a fungal infection.

"Not to worry," Schaffner said.

• 27 Devastating Infectious Diseases
• 10 Bizarre Diseases You Can Get Outdoors
• Here's a Giant List of the Strangest Medical Cases We've Covered

Originally published on Live Science.

Coughing up blood is an alarming symptom, but it's not particularly rare. Even so, one man in California shocked his doctors when he coughed up an unusual-looking blood clot: It was in the shape of his lung.

The 36-year-old man was being treated for a serious heart condition, according to a new report of the case, published Nov. 29 in The New England Journal of Medicine. He had chronic heart failure, which means the heart muscle can't pump enough blood to meet the body's normal demands.

His condition was so severe that doctors put him on a machine called a ventricular assist device, which helps the heart pump blood. Because these machines can also increase the risk of blood clots, he was prescribed a blood-thinner medication.

However, these medications also increase the risk of bleeding, including coughing up blood. Indeed, the patient had several coughing episodes in which he expelled small amounts of blood, according to the report. But then, during an "extreme bout of coughing," the patient spit out an "intact cast" of the right bronchial tree. In other words, it was a mold (cast) made of clotted blood in the shape of the lung's branched airway passages known as bronchi.  

"We were astonished," Dr. Georg Wieselthaler, a heart and lung surgeon at the University of California, San Francisco (UCSF), who treated the patient, told The Atlantic. "It's a curiosity you can't imagine — I mean, this is very, very, very rare."

It's less rare for patients to cough up bronchial "casts" made of other substances, such as lymph or mucus. But blood is less sticky and sturdy than these other substances, meaning that a cast made of blood is less likely to hold together when coughed up, The Atlantic reported.

Wieselthaler told The Atlantic that in this case, the patient had an infection that increased levels of a protein called fibrinogen, which helps blood clots form; and higher levels of fibrinogen could have helped the man's large clot to stay intact when it was coughed up.

Even though the man had no further episodes of coughing up blood, he unfortunately died a week later from complications of heart failure.

Wieselthaler's colleague, Dr. Gavitt Woodard, a clinical fellow at UCSF, told The Atlantic that one reason they decided to publish the image was to show the "beautiful anatomy of the human body."

• 11 Surprising Facts About the Respiratory System
• 12 Amazing Images in Medicine
• 27 Oddest Medical Cases

Originally published on Live Science.

ALBUQUERQUE, N.M. — Ancient organs rarely fossilize, so paleontologists were stunned to find the incredibly well-preserved remains of a lung that belonged to bird from the dinosaur age.

Initially, scientists were excited to describe the specimen of Archaeorhynchus spathula, a bird that lived about 120 million years ago, because its fossil had exquisitely preserved feathers, including a unique pintail that isn't seen in any other Cretaceous bird, but is common in birds nowadays.

A closer inspection, however, revealed that the bird's lungs had also fossilized, meaning the paleontologists had discovered the oldest "informative" fossilized lung on record (more on that later) and the oldest fossilized lung ever seen in a bird fossil, said study co-lead researcher Jingmai O'Connor, a professor with the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences. [Tiny Dino: Reconstructing Microraptor's Black Feathers]

The fossil itself is from the early Cretaceous Jehol Lagerstätte formation in northeastern China, but O'Connor and her colleagues found it at the Shandong Tianyu Museum of Nature, in Pingyi, where an avid fossil collector houses the thousands of bird fossils he's purchased over the decades.

This is the fifth described A. spathula specimen — a toothless, pigeon-size bird — but it's by far the best preserved, O'Connor said. That's especially because of the speckled, white material in its chest cavity that appears to be a fossilized lung.

The finding reveals that the lung structures in early birds are similar to the lungs of modern birds, the researchers said. This means that A. spathula likely had unidirectional airflow in its lungs — the air that flowed in was largely fresh and full of oxygen, unlike the air in mammals' lungs, which is mixed with both new and previously breathed air, meaning it has a lower oxygen content.

"Lungs of birds are very different from our lungs and [had] much more complex structures," P. Martin Sander, a paleontologist at the University of Bonn in Germany who was not involved in the research, told Live Science in an email. "They are kind of like a bag pipe, with an air management system (the air sacs) separated from the gas exchanger (the lung proper) which is preserved here."

Living crocodilians also have lungs with unidirectional airflow, and paleontologists considered it to be ancestral in early feathered dinosaurs. But evidence for such a lung structure in an early bird has been elusive, until now.

Deep dive

To get a better look at the supposed lung remains, "we went and extracted some samples, put them in the SEM [scanning electron microscope] and — boom — lung tissue," O'Connor told Live Science. Because O'Connor specializes in skeletal (not organ) anatomy, she roped in John Maina, a professor of zoology at the University of Johannesburg in South Africa, who is an expert on the lungs of living birds.

"I was like, 'Look, do you think this is lung tissue? If you do think it is, then none of us digging-in-the-dirt paleontologists can argue with you,'" O'Connor said. Maina's contribution was so critical, that he became a co-researcher on the study.

An analysis of the tissue showed that it contained structures that resemble blood capillaries, which absorb oxygen to help power the highly energetic flight of birds. "Avian flight is the most physically demanding form of locomotion, so you need a lot of oxygen for it," O'Connor said. [Photos: Dinosaur-Era Bird Sported Ribbon-Like Feathers]

It's possible that this unique structure was unique to Ornithuromorpha, a clade (group) of ancient birds that survived the mass extinction about 66 million years ago and includes today's living birds. "Maybe this specialization was only in that clade and was one of the many factors that allowed [their] survival," O'Connor said.

What's more, it appears that the fossilized lung was embedded in the bird's ribs, just as bird lungs are today. Unlike human lungs, which expand with every breath, bird lungs are rigid, so they can easily inhale and exhale at the same time, O'Connor said.

The tissue doesn't appear to be leftover stomach contents, as those usually preserve as black, carbonized organic matter, she noted. Moreover, the preserved tissue is paired, just like a modern lung. There are no other paired organs that it could be, and it's likely not the liver (which is lobed) because that organ has a high iron content and usually preserves as red, O'Connor said.

However, this specimen isn't the oldest lung on record. That honor goes to Spinolestes, an early Cretaceous mammal that has fossilized lungs about 5 million years older than the newly analyzed bird. But those lung fossils didn't preserve any microstructure and don't provide much information about Spinolestes, other than that it likely had a muscular diaphragm. So, O'Connor is calling the A. spathula fossil "the first informative lung remains," because they shed light on bird evolution.

The lung findings are "cool stuff," because it shows"what the lung of an early bird looked like," Sander said. However, because it's so rare to see a fossilized organ, more work is needed to verify that this is a lung, he said.

"We should apply various other analytical techniques to confirm that the area in the fossil really is lung," he said. "But I would not be surprised if lung can fossilize because of its high iron content because the lung is rich in blood."

The research was presented here at the 78th annual Society of Vertebrate Paleontology meeting yesterday (Oct. 18). It will be published in the journal the Proceedings of the National Academy of Sciences on Monday (Oct. 22).

Originally published on Live Science.

A persistent myth about milk — that drinking it can lead to the production of more gooey mucus in your body's airways — is completely false, a new review finds.

The myth is so persistent that some parents have stopped giving milk to children with chronic respiratory conditions, such as asthma and cystic fibrosis, out of concern that drinking milk might make it harder for their children to breathe. [The 7 Perfect Survival Foods]

But the milk-mucus connection is simply a myth, said review author Dr. Ian Balfour-Lynn, a pediatric pulmonologist at Royal Brompton Hospital in London. And when people take this myth as true medical advice, it could have serious consequences: Not giving milk to children can make it challenging for them to get enough calcium, vitamins and calories, Balfour-Lynn said. Children who don't drink enough milk are also more prone to fractures and shorter stature, studies show.

It's unclear exactly when the milk myth got started. It's possible that it came from Moses Maimonides (1135-1204), a philosopher and doctor who wrote that milk causes "a stuffing in the head." Moreover, traditional Chinese medical texts have linked dairy consumption with "a humidifying effect and thicker phlegm," Balfour-Lynn wrote in the review, which was published online yesterday (Sept. 6) in the journal Archives of Disease in Childhood.

Even the influential "Dr. Spock's Baby and Child Care" book, of which more than 50 million copies have been sold since its publication in 1946, repeats this claim. A 2011 edition of the book states that "dairy products may cause more mucus complications and more discomfort with upper respiratory infections," Balfour-Lynn found while researching the myth.

Given the myth's reach, it's no surprise that in a study of 345 randomly selected shoppers in Australia, 51 (46 percent) of the 111 whole-milk drinkers "agreed" that milk causes mucus, according to research published in 2003 in the journal Appetite. However, the type of milk appeared to influence the shoppers' decision: Just 30 (25 percent) of the 121 reduced-fat-milk drinkers and only 12 (11 percent) of the 113 soy-milk drinkers agreed with this statement, the study found. 

The myth may persist because of milk's unique properties. Milk is an emulsion, meaning it has droplets of one liquid suspended in another liquid. (In milk's case, fat droplets are suspended in water.) When a person drinks milk, the milk mixes with their saliva.

The sticky compounds in saliva can boost milk's viscosity, or thickness, and volume, Balfour-Lynn told Live Science. The resulting "thickness coating the mouth and the after feel — when small amounts of emulsion remain in the mouth after swallowing" may make people think that drinking milk leads to a sudden spike in mucus, he noted.

Another potential explanation for the myth is that when milk breaks down, it releases a protein that is known to boost the activity of a gene involved in mucus production. But this particular mucus production happens in the bowel, not the respiratory tract, Balfour-Lynn said. [10 Celebrities with Chronic Illnesses]

This mucus could affect the respiratory tract only if the bowel were weakened by infection, which would allow the mucus to travel elsewhere in the body, he said. This wouldn’t happen with a common cold, although it's possible it could affect people with cystic fibrosis, which is sometimes accompanied by gut inflammation, Balfour-Lynn said.

However, small studies dating back to 1948 show that drinking milk is not associated with an increase of mucus in the respiratory tract, he found.

In all, "while certainly the texture of milk can make some people feel their mucus and saliva is thicker and harder to swallow, there is no evidence (and indeed evidence to the contrary) that milk leads to excessive mucus secretion," Balfour-Lynn wrote in the review. "The milk-mucus myth needs to be rebutted firmly by healthcare workers."

The review is an important one because it helps raise awareness that it's perfectly healthy to drink milk while having respiratory problems, said Dr. Corey Wasserman, a pediatrician at Weill Cornell Medicine in New York City, who was not involved with the review.

It's common to hear parents ask about the milk myth during flu and cold season, Wasserman said. She tells patients exactly what this review found — that milk does not increase mucus or phlegm production. In addition, cold milk can help hydrate and soothe the throat of a sick child in need of calories, Wasserman told Live Science.

Original article on Live Science.

It really did go down the wrong pipe: A striking new image shows a chicken bone lodged in an Australian man's lung. What's more, the bone was stuck there for five days before it was discovered.

The 78-year-old man initially went to the emergency room right after he choked while eating chicken, according to a new report of his case. He told doctors that he felt like he had something stuck in his throat; however, an X-ray of his neck and chest didn't show anything suspicious.

So, doctors assumed that whatever had been stuck had been dislodged, and the man was sent home.

However, five days later, the man was back in the ER — he had developed a fever and shortness of breath, and there was a high-pitched wheezing sound when he inhaled, according to the report, published yesterday (May 2) in The New England Journal of Medicine. [11 Weird Things People Have Swallowed]

This time, doctors performed a CT scan, which showed a chicken vertebra bone in the right "mainstem bronchus," the airway that branches off from the trachea into the lung. An area in the man's right lung wasn't inflating properly, but this symptom was minor, the report said.

But how did an inhaled chicken bone go undetected for five days?

When an adult accidentally inhales a foreign body, the diagnosis can sometimes be delayed by weeks or months — or even years. A 2013 report from Canada described the case of a woman who went 22 years with a bone fragment lodged in her bronchus. And last year, a 47-year-old man in England learned that he had a tiny toy traffic cone lodged in his airway, from an incident 40 years earlier.

A delayed diagnosis can happen because, if a foreign body is relatively small and doesn't completely block the airway (which would cause asphyxiation), it can pass into one of the lungs and cause less-severe symptoms than it would if it completely blocked the airway, according to a 2012 report of a case of foreign-body inhalation. What's more, up to 80 percent of foreign bodies are not visible on chest X-rays alone, according to the 2013 report.

Dr. Robert Glatter, an emergency-medicine physician at Lenox Hill Hospital in New York City who was not involved in the man's case, said it wouldn't be unreasonable to discharge a patient who came in for a choking episode if the patient didn't have breathing or swallowing problems and their initial X-rays didn't show a foreign body (as was the case for the Australian man). In some cases, doctors may do a CT scan in addition to the X-ray, if they suspect a foreign body in a person's lungs. But "the problem is that so many patients [show these symptoms] and they clear their airways [on their own], and they go on to do fine," Glatter told Live Science. Only a small proportion of people end up having a delayed presentation of a foreign body in the lungs, although it's still a problem that doctors worry about, he added.  

A delayed diagnosis can lead to complications, including post obstructive pneumonia, or inflammation that occurs around the foreign body in the lungs, Glatter said.

In the Australian man's case, he received a bronchoscopy, a procedure in which a long, flexible tube with a camera is inserted into the lung, to remove the chicken bone. The patient "recovered well after the procedure" and was discharged from the hospital three days later, the report said.

Original article on Live Science.

Rats, apparently, can smell tuberculosis.

In fact, not only can they smell it, but they're also significantly better at sniffing out the illness than existing tests that doctors use to test for the disease in children. Current pediatric tuberculosis (TB) tests have a sensitivity of just 30 to 40 percent, meaning that if a doctor tests a child sick with TB for the disease, there's just a 30 to 40 percent chance that the test will return a positive result.

But add in a sniff from a trained rat, according to a paper published April 4 in the journal Pediatric Research, and the sensitivity of the test jumps by nearly 40 percent.

That's a big deal, because while TB is very difficult to test for in kids, it's still a major cause of death worldwide and is difficult to treat unless caught early. Of the 1.3 million people who died in 2016 of TB, the researchers wrote, 130,000 were children, many in sub-Saharan Africa. It's hard to test for TB, they wrote, because young kids have trouble producing enough sputum (a mixture of mucus and saliva) to culture the bacteria, or grow a sample of it to test it. [27 Devastating Infectious Diseases]

The low sensitivity of the test makes it difficult for doctors to rule out TB when patients might not have it at all or to detect it when a child does have TB but doctors aren't certain it's present

(While the TB test has a low sensitivity, it does have a high specificity. That means that if someone does have a positive test result, they almost certainly really have TB and not a different disease, which isn't the case for all medical tests.)

The researchers, based in Tanzania and Mozambique, decided to do the study after hearing stories of certain lung diseases having strong, identifiable smells. So, they trained African giant pouched rats (Cricetomys ansorgei) to sniff out certain compounds produced by TB. Then, the doctors rode motorbikes around to local hospitals, collected sputum samples from patients and evaluated how the sniff test improved the results.

Unfortunately, the paper didn't report exactly how the rats were trained to identify the smell of TB. But the study did note that they were rewarded with food and given wheels to play on in their downtime.

The 40 percent increase in sensitivity made a big difference for patients. The researchers reported that after existing TB tests detected the disease in 34 children ages 1 to 5, the rats detected an additional 23 cases (all later confirmed by repeating, in some cases several times, the sputum test). Similarly, when existing tests caught 94 cases of TB in kids ages 6 to 10, the rats caught an additional 35 cases. In adolescents, the existing test caught 775 cases, and the rats added 177. In adults, the existing tests caught 7,448 cases, and the rats added 2,510 confirmed TB cases.

In other words, the rats became less useful as the patients got older, but in every age group, the rodents significantly improved upon existing tests.

This isn't the end of the road for this line of research. The authors of the paper wrote that more research is needed to determine just how sensitive rats' noses are to TB and how best to deploy the animals.

Originally published on Live Science.

Finally, some good news about airplane travel: If you're on a plane with a sick passenger, you probably won't get sick.

That's the conclusion of a new study that looked at how respiratory viruses spread on airplanes.

Researchers found that only people who were seated in the same row as a passenger with the flu, for example — or one row in front of or behind that individual — had a high risk of coming down with the illness after the flight. All other passengers had only a very slim chance of getting sick, according to the findings, which were published today (March 19) in the journal Proceedings of the National Academy of Sciences.  

Media reports have not necessarily presented accurate information about the risk of transmitting infections on an airplane, said Dr. Amesh Adalja, a spokesperson for the Infectious Disease Society of America and a senior scholar at the Johns Hopkins Center for Health Security, who was not involved in the new study. [27 Devastating Infectious Diseases]

These new findings, however, should provide reassurance to airplane passengers that only the people in the immediate vicinity of an infected person may be exposed to respiratory infections and that it won't affect everyone on the plane, Adalja told Live Science.

Prior to the new study, little was known about the risks of directly transmitting common respiratory viruses, such as the flu or common cold, on an airplane, the researchers said. So, to evaluate the risks of infection, the study team flew on 10 different cross-country flights in the U.S during flu season.

The flights ranged in length from 3.5 to 5 hours, and most of the planes were at full capacity. While on board, the researchers tracked the movements and behaviors of passengers and crew within the economy cabin of a single-aisle aircraft, noting how frequently people left their seats or interacted with others —two activities that can spread respiratory infections. Before, during and after the flights, the researchers also collected samples from the air on the plane and from commonly touched surfaces that could be contaminated with viruses, such as seat-belt buckles, tray tables and bathroom door handles. 

An analysis of those samples turned up no evidence of the presence of 18 common respiratory viruses.

Viruses on a plane

The researchers used the data on passenger and crew movements to create a computerized model simulating the risk of transmitting the flu from an infected passenger sitting in an aisle seat in the middle of the aircraft. This seat location has the greatest potential to share an infection because this person will have more contact with other passengers while moving through the cabin, and people in aisle seats leave their seats more frequently, according to the findings. (The study showed that 80 percent of passengers in aisle seats, 62 percent in middle seats and 43 percent in window seats moved from their seats at least once during the flight.)

The analysis showed that passengers sitting within two seats on either side of a person infected with the flu, as well as those sitting one row in front of and one row behind this individual, had about an 80 percent chance of getting sick. But other passengers were largely safe from infection; they had a less than 3 percent chance of coming down with the flu, according to the model. [Germs on the Big Screen: 11 Infectious Movies]

The study used rigorous measurements and showed the contact patterns and movements of passengers and crew members on the plane, which can facilitate or hinder the transmission of respiratory viruses, Adalja said. When traveling during flu season, the best way that passengers might potentially avoid the illness is by getting a flu shot, he added.

If you get stuck next to someone who's sick, chances are, you won't be able to change your seat. But there are still some steps you can take to reduce your chances of catching their illness. If there is a passenger nearby who is coughing or sneezing, look away from them, if possible, Adalja recommended. To minimize your exposure to germs, avoid touching your face and eyes, limit your contact with shared surfaces and use hand sanitizer, he said.

There were some limitations of the new study, however. It did not evaluate flights shorter than 3.5 hours or longer than 5 hours, and it looked only at single-aisle planes. In addition, the researchers built their model using data from just 10 flights. The researchers also acknowledged that some transmission of respiratory infections could occur while passengers are waiting in the airport or when they're boarding and exiting the plane.

Originally published on Live Science.

A mysterious lung disease is striking dentists in Virginia, according to a new report.

So far, health officials have identified nine dentists or dental workers who were diagnosed with the disease, called idiopathic pulmonary fibrosis, all of whom were treated at the same specialty clinic in Virginia, according to the report, from the Centers for Disease Control and Prevention (CDC). The disease is often fatal: Of the nine cases, seven have died, the report said.

Overall, dentists made up 1 percent of idiopathic pulmonary fibrosis cases seen at the clinic. But that's still a strikingly high rate — it's 23 times higher than what would be expected based on the number of dentists in the U.S. population. [11 Surprising Facts About the Respiratory System]

And the cause of the disease still isn't clear.

However, health officials are following some leads: It's possible, for example, that the dentists were exposed to something on the job that might have increased their risk of the disease, the researchers said.

Idiopathic pulmonary fibrosis is a progressive disease that occurs when tissue deep in the lungs becomes thick and stiff, or scarred, according to the National Heart, Lung and Blood Institute. This scarring prevents the lungs from working properly. Doctors don't know the cause of the disease — by definition, "idiopathic" means "arising spontaneously or from an obscure or unknown case," according to Merriam-Webster — and there is no cure. In many cases, people with the disease live only about three to five years after their diagnosis, the CDC said.

Although the disease has been linked with certain jobs that involve exposure to dust, wood dust and metal dust, the new report marks the first time that researchers have found a connection between the disease and being a dental worker.

The cluster of cases first came to light when a Virginia dentist went to get treatment for idiopathic pulmonary fibrosis at a clinic and he realized that other dentists in his area had also been treated at the clinic for the same condition.

The dentist contacted the CDC with his concerns, which led health officials to identify the eight other cases that occurred between 2000 and 2015. All of the patients were men, ages 49 to 81 years old, and eight were dentists; one patient was a dental technician.

Of the two patients who were still alive, only one was able to give an interview to health officials. The man told the CDC that during his dental career, he had polished dental appliances and prepared dental impressions without a wearing a mask. This means he could have been exposed to particles of silica in the air or other compounds that can have potentially toxic effects on the respiratory system, the report said.

Still, the researchers only found an association between dental work and this lung disease, and cannot say for certain whether the work did indeed cause the disease. There may be other factors involved — for instance, the man who gave the interview also said he was a street sweeper for three months before he went to dental school, which would also have exposed him to dust.

The researchers recommend that dental workers wear certified respiratory masks if they perform tasks that could result in respiratory hazards and the work area is not well ventilated.

The report concluded that more work is needed to better understand the risk of this lung disease in dental workers "to develop strategies for prevention of potentially harmful exposures."

Original article on Live Science.

Lungs are sacks of tissue located just below the rib cage and above the diaphragm. They are an important part of the respiratory system and waste management for the body.

Size

A person's lungs are not the same size. The right lung is a little wider than the left lung, but it is also shorter. According to York University, the right lung is shorter because it has to make room for the liver, which is right beneath it. The left lung is narrower because it must make room for the heart.

Typically, a man's lungs can hold more air than a woman's. At rest, a man's lungs can hold around 750 cubic centimeters (about 1.5 pints) of air, while a woman's can hold around 285 to 393 cc (0.6 to 0.8 pints) of air, according to York University. "The lungs are over-engineered to accomplish the job that we ask them to do," said Dr. Jonathan P. Parsons, a professor of internal medicine, associate director of Clinical Services, and director of the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine at the OSU Asthma Center at The Ohio State University. "In healthy people without chronic lung disease, even at maximum exercise intensity, we only use 70 percent of the possible lung capacity." 

Function

According to the American Lung Association, adults typically take 15 to 20 breaths a minute, which comes to around 20,000 breaths a day. Babies tend to breath faster than adults. For example, a newborn's normal breathing rate is about 40 times each minute while the average resting respiratory rate for adults is 12 to 16 breaths per minute. [Respiratory System: Facts, Function and Diseases]

Though breathing seems simple, it is a very complex process.

The right lung is divided into three different sections, called lobes. The left lung has just two lobes. The lobes are made of sponge-like tissue that is surrounded by a membrane called pleura, which separates the lungs from the chest wall. Each lung half has its own pleura sack. This is why, when one lung is punctured, the other can go on working. 

The lungs are like bellows. When they expand, they pull air into the body. When they compress, they expel carbon dioxide, a waste gas that bodies produce. Lungs do not have muscles to pump air in and out, though. The diaphragm and rib cage essentially pump the lungs.

As a person breathes, air travels down the throat and into the trachea, also known as the windpipe. The trachea divides into smaller passages called the bronchial tubes. The bronchial tubes go into each lung. The bronchial tubes branch out into smaller subdivisions throughout each side of the lung. The smallest branches are called bronchioles and each bronchiole has an air sac, also called alveoli. There are around 480 million alveoli in the human lungs, according to the Department of Anatomy of the University of Göttingen.

The alveoli have many capillary veins in their walls. Oxygen passes through the alveoli, into the capillaries and into the blood. It is carried to the heart and then pumped throughout the body to the tissues and organs.

As oxygen is going into the bloodstream, carbon dioxide passes from the blood into the alveoli and then makes its journey out of the body. This process is called gas exchange. When a person breathes shallowly, carbon dioxide accumulates inside the body. This accumulation causes yawning, according to York University. 

The lungs have a special way to protect themselves. Cilia, which look like a coating of very small hairs, line the bronchial tubes. The cilia wave back and forth spreading mucus into the throat so that it can be dispelled by the body. Mucus cleans out the lungs and rids them of dust, germs and any other unwanted items that may end up in the lungs. 

Diseases & conditions

The lungs can have a wide range of problems that can stem from genetics, bad habits, an unhealthy diet and viruses. "The most common lung related conditions I see are reactive airways or asthma, as well as smoking-related emphysema, in my general practice," Dr. Jack Jacoub, a medical oncologist and director of thoracic oncology at Memorial Care Cancer Institute at Orange Coast Memorial Medical Center in Fountain Valley, California, told Live Science. 

Asthma, also called reactive airway disease before a diagnosis of asthma, is a lung disease where the air passageways in the lungs become inflamed and narrowed, making it hard to breath. In the United States, more than 25 million people, including 7 million children, have asthma, according to the National Heart, Lung, and Blood Institute.

Lung cancer is cancer that originates in the lungs. It is the No. 1 cause of deaths from cancer in the United States for both men and women, according to the Mayo Clinic. Symptoms of cancer include coughing up blood, a cough that doesn't go away, shortness of breath, wheezing, chest pain, headaches, hoarseness, weight loss and bone pain.

Chronic obstructive pulmonary disease (COPD) is long-term lung disease that prevents a person from breathing properly due to excess mucus or the degeneration of the lungs. Chronic bronchitis and emphysema are considered COPD diseases. About 11.4 million people in the United States suffer from COPD, with about 80 to 90 percent of COPD deaths attributed to smoking, according to the American Cancer Society. 

Sometimes, those with COPD get lung transplants, replacement lungs garnered from organ donors, to save their lives. Research is also being done on growing new lungs from stem cells. Currently, stem cells extracted from the patient's blood or bone marrow are being used as a treatment to heal damaged lung tissue.

Lung infections, such as bronchitis or pneumonia, are usually caused by viruses, but can also be caused by fungal organisms or bacteria, according to Ohio State University. Some severe or chronic lung infections can cause fluid in the lungs and other symptoms such as swollen lymph nodes, coughing up blood and a persistent fever. 

Being overweight can also affect the lungs. "Yes, being overweight does adversely affect the lungs because it increases the work and energy expenditure to breath," said Jacoub. "In the most extreme form, it acts like a constricting process or vest around the chest such as that seen in the 'Pickwickian syndrome.'"

Promoting good lung health

One of the best ways to promote good lung health is to avoid cigarette smoke because at least 70 out of the 7,000 chemicals in cigarette smoke damages the cells within the lungs. According to the Mayo Clinic, people who smoke have the greatest risk of lung cancer. The more a person smokes, the greater the risk. Those who smoke are 15 to 30 times more likely to get lung cancer according to the Centers for Disease Control and Prevention. If a person quits, their lungs can heal from much of the damage, said Dr. Norman Edelman, a senior scientific adviser for the American Lung Association and a specialist in pulmonary medicine. [Do Smokers' Lungs Heal After They Quit?]

The Rush University Medical Center also suggests practicing deep breathing exercises, staying hydrated and regular exercise to keep the lungs healthy. Parsons also recommends having homes tested for radon. "Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in the ground. It typically leaks into a house through cracks in the foundation and walls. Radon is the main cause of lung cancer in nonsmokers, and the second-leading cause of the disease after smoking," said Parsons.

Additional resources

• American Lung Association
• Taylor and Francis Online: Experimental Lung Research
• Lung Institute: Stem Cell Therapy for Lung Disease
• Scientific American: If a person's lung size cannot increase, how does exercise serve to improve lung function?
• National Institute of Health: Variability in the size of airspaces in normal human lungs as estimated by aerosols

Breathe deep

An estimated 3.3 million deaths worldwide are caused by outdoor air pollution, according to a study published in September 2015 in the journal Nature. Of those deaths, about 75 percent are from heart attacks or strokes, while about 25 percent are from lung-related ailments, Live Science previously reported.

The majority of these deaths — about 75 percent — happen in Asia, where air pollution is particularly severe, especially in China and India. Much of this pollution results from burning fossil fuels, and global carbon emissions are on track to reach record highs worldwide in 2017, according to a report released Nov. 13, 207, by the Global Carbon Project.

The link between cardiovascular health and air pollution is well-known, but recent studies are providing a growing body of evidence that polluted air can have a range of negative impacts on physical and mental health, leading to ailments that can in some cases prove lethal. 

Poor quality sperm

Elevated levels of air pollution have been linked to lower sperm quality, according to a study from Taiwan published Nov. 13 in the journal Occupational and Environmental Medicine.

Researchers investigated sperm production, activity and appearance over a series of three-month periods, in nearly 6,500 men living in Taiwan that were between the ages of 15 and 49. They then estimated how the subjects' sperm would be affected over a two-year period.

The scientists found an association between exposure to fine particulate matter in the air and abnormal sperm shape and size, they reported in the study. However, the amount of sperm produced tended to be higher when air pollution was present, perhaps to compensate for the compromised morphology of the individual sperm cells, the study authors noted. 

Fractures from bone density loss

In older people, osteoporosis — age-related bone density loss — is the most common cause of bone fractures, leading to approximately 8.9 million fractures in people around the world each year, according to the International Osteoporosis Foundation. And there may be a link between air pollution and greater vulnerability to broken bones from osteoporosis, scientists reported in a study published Nov. 9, 2017, in the journal The Lancet: Planetary Health.

Researchers first evaluated data from 9.2 million people over the age of 65, investigating hospital admissions for bone fractures in the northeast and mid-Atlantic United States from January 2003 to December 2010. They compared their findings about patients with broken bones to levels of particulate matter in the air — a component of air pollution — and found that the risk of bone fractures increased when pollution levels were higher, particularly in low-income communities.

In a second stage of analysis, the researchers looked at 692 middle-age men in the Boston area, examining the impacts of their exposure to air pollution over time. They observed that men living in regions where pollution from car emissions was higher, had lower levels of parathyroid hormone, which contributes to building and maintaining bone mass. The men in highly polluted areas also had greater drops in their bone density levels than study subjects living in less polluted neighborhoods, the scientists reported.   

Stroke risk

Strokes kill an estimated 5 million people worldwide each year — they are the fifth leading cause of death in the United States and are a major cause of long-term disability, according to the Centers for Disease Control and Prevention. And incidences of stroke are on the rise, leading a team of researchers to question whether environmental factors could be to blame.

Scientists reviewed 94 studies reporting 6.2 million stroke cases in 28 countries around the world, occurring between 1948 and 2014. They were looking for associations between short-term exposure to air pollution — evaluating pollution from gasses and from particles in the air — and hospital admission or death resulting from a stroke.

They discovered a "marked and close association" between short periods of exposure to certain levels of air pollution and "adverse stroke outcomes" — disabilities and deaths — which they described in a study published in May 2015 in the journal BMJ. Though only 20 percent of the studies represented developing countries, air pollution levels tended to be highest there, and the number of strokes reported were also disproportionately high, the scientists wrote in the study.  

Kidney disease

A recent study of U.S. veterans suggested that air pollution exposure could be connected to declining kidney function, the emergence of kidney disease and even kidney failure. In the study, which was published online on Sept. 21 , 2017, in the Journal of the American Society of Nephrology, researchers reported that even low levels of air pollution could affect the kidneys, and its impact would increase linearly as pollution levels rose.

The scientists analyzed medical data representing over 2 million U.S. veterans and spanning more than eight years. They also collected information on the air pollution levels in areas where the veterans lived, which was gathered by NASA satellites. Their findings noted that air pollution levels below the recommended levels established by the Environmental Protection Agency (EPA) could be linked to kidney deterioration, with thousands of new cases of kidney disease or failure developing each year in areas where pollution levels were higher than the recommended limit, the study authors wrote.

"Even levels below the limit set by the EPA were harmful to the kidneys," Dr. Ziyad Al-Aly, director of clinical epidemiology at the Veterans' Affairs Saint Louis Health Care System, said in a statement.

"This suggests that there is no safe level of air pollution," Al-Aly added. 

High blood pressure

A study of over 41,000 people living in Spain, Germany, Denmark, Sweden and Norway, found that air pollution could increase the risk of developing high blood pressure, or hypertension, as much as being overweight would. The study — published in October 2016 in the European Heart Journal — was part of an ongoing project known as "European Study of Cohorts for Air Pollution Effects" (ESCAPE), which is exploring how human health in Europe is affected by long-term exposure to air pollution.

None of the people who joined the study in 2008 suffered from hypertension when research began. But during follow-up visits with the scientists years later, 6,207 people — 15 percent of the study subjects — had developed hypertension or were taking medication to lower their blood pressure.

In the study, researchers discovered that in the cities' most polluted areas, one more person per 100 would be likely to develop high blood pressure, than in populations living in regions where the air was cleaner.

During three two-week periods between 2008 and 2011, scientists measured air pollution levels in 60 sites. They found the risk of hypertension in people that lived in the most polluted areas increased by 22 percent, compared to people living in areas where pollution was lowest.

"Our findings show that long-term exposure to particulate air pollution is associated with a higher incidence of self-reported hypertension and with intake of anti-hypertensive medication," study lead author Barbara Hoffman, a professor of environmental epidemiology at the Centre for Health and Society at Heinrich-Heine-University in Düsseldorf, Germany, said in a statement.

"As virtually everybody is exposed to air pollution for all of their lives, this leads to a high number of hypertension cases, posing a great burden on the individual and on society," Hoffman said.

Negative birth impacts

Recently, a study in mice found that exposure to air pollution during pregnancy could be connected to premature birth and low birth weight. These effects were found to be more likely to develop if exposure to polluted air occurred during the period of pregnancy in mice that was comparable to the first or second trimester in humans, according to research published on July 27 in the journal Environmental Health Perspectives.

In the study, the pregnant mice inhaled air containing invisible particles produced by burning fossil fuels, at levels that matched those in urban areas that are considered to be highly-polluted. The scientists discovered that exposure to polluted air during the earliest stage of pregnancy led to premature birth in 83 percent of the mice. If the mice were exposed to the pollutants from conception through the period marking the second trimester in a human mother, birth weight in 50 percent of the litters dropped by more than 11 percent.

"This first study of this problem in mice adds to the growing body of evidence that inhalation of particulate matter from implantation through the second trimester of pregnancy is potentially dangerous," study lead author Jason Blum, an assistant professor in the Department of Environmental Medicine at NYU School of Medicine, said in a statement.

Mental health issues

In addition to taking a toll on the body, air pollution can also fuel psychological distress, according to a study published in the November 2017 issue of the journal Health & Place.

For the study, researchers investigated air quality data from an air pollution database, alongside survey results from 6,000 participants from across the U.S. They assessed levels of psychological distress in participants using a scale that evaluated their descriptions of feelings of hopelessness, sadness, nervousness and other similar emotions.  

The scientists found that as the amount of pollution in the air went up, so did the risk of the people in the study reporting instances of psychological distress. Scores representing distress were 17 percent higher in areas where air pollution was higher, and trends emerged when the study authors looked at the race of participants. In regions where the air was more toxic, the level of distress reported by black men was 34 percent higher than in white men, and the difference between black men and Latino men was even more pronounced — about 55 percent higher, the scientists reported.

And white women were especially susceptible to psychological upset in the presence of more toxic air. About 39 percent of the women in the study reported greater distress in response to rising levels of pollution, according to the study.

"This is really setting out a new trajectory around the health effects of air pollution," study co-author Anjum Hajat, an assistant professor of epidemiology in the University of Washington School of Public Health, said in a statement.

"The effects of air pollution on cardiovascular health and lung diseases like asthma are well established, but this area of brain health is a newer area of research," Hajat said.

Heart attack

Inhaling polluted air can cause heart inflammation and contribute to cardiovascular disease and an increased risk of death, according to the American Heart Association. In fact, air pollution causes as many heart attacks as alcohol, coffee or exercise, according to a study published in February 2011 in the journal The Lancet.

Researchers examined 36 studies describing people who had suffered non-fatal heart attacks in different countries between 1960 and 2010. They investigated various risk factors that can contribute to heart attacks, and assessed how often people came inot contact with the different factors, to determine which triggered heart attacks more frequently, Live Science previously reported.

The scientists found that air pollution accounted between 5 and 7 percent of heart attacks, while drinking alcohol or coffee accounted for about 5 percent of heart attacks apiece, and exercise covered about 6 percent. 

A liposuction procedure turned nearly deadly for a 45-year-old woman in England,  according to a new report of her case.

The woman developed a condition called fat embolism syndrome, a rare but dangerous complication that can arise from the operation, according to the report, published today (Sept. 25) in the journal BMJ Case Reports.

Fat embolism syndrome refers to a condition in which a globule of fat gets into a person's bloodstream and blocks off blood vessels, thus preventing blood flow, the authors wrote in the report. The condition is "notoriously difficult" to diagnose, and symptoms usually don't begin until 24 to 72 hours after the initial event. If left untreated, it can lead to inflammation throughout the body and organ failure. [27 Oddest Case Reports]

In the woman's case, she underwent liposuction on her knees and lower legs. The goal of the surgery was to remove some of the bulk from her legs so that it would be easier for her to walk, the authors wrote. The surgery was uneventful, and afterward, she was transferred to another unit of the hospital to be monitored while she recovered.

Within 40 hours of the surgery, however, doctors noticed that something was amiss: The women's heart started racing, she became drowsy and her breathing slowed, causing a buildup of carbon dioxide in her blood, according to the report.

The woman was transferred to the intensive care unit, where doctors performed a battery of tests to figure out what was wrong, the authors wrote. But "currently, there are no gold standard nor validated diagnostic criteria for [fat embolism syndrome]," according to the report. In other words, there's no clear way to diagnose the condition. Indeed, recognizing the condition "remains a significant clinical challenge for most physicians even though it was first recognized as early as 1873," they wrote.

The doctors who treated the woman wrote that diagnosing fat embolism syndrome often depends on ruling out other problems. In addition, certain risk factors can increase a patient's likelihood of developing the condition, they wrote. In the woman's case, a high body mass index, swelling in the legs and the removal of a large amount of fat were all risk factors, according to the report.

Fat embolisms caused by liposuction are rare, the doctors wrote in the report; only a few cases have been documented in the medical literature, none of which took place in the U.K., where the woman was treated. Instead, fat embolisms are most commonly linked to bone fractures and major traumas, such as serious car accidents. Liposuction is "generally a safe procedure," the doctors added.

The woman was kept in the intensive care unit for 12 days, where she was placed on a ventilator to help her breathe for the first eight days, according to the report. The doctors noted that there aren't any specific treatments for fat embolism syndrome; instead, patients are given supportive care until the body recovers on its own.

The woman was sent home two days after being moved from intensive care to a less intensive ward, according to the report. When the doctors checked in on her two months later, she was doing fine and had recovered well, they said.

Originally published on Live Science.

Most fish would be left high and dry during drought periods when the bodies of water they inhabit shrink and disappear — but African lungfish aren't most fish.

Even under normal conditions, lungfish are air breathers, relying on gills that interact with functional lungs to provide their oxygen. But when temperatures heat up and their watery habitats disappear, African lungfish respond by tunneling underground and generating a leathery enclosure that retains moisture but still allows enough air flow around their bodies for them to keep breathing — with no water required.

A video recently shared online by the National Science Foundation (NSF) reveals lungfish in Ghana as they are extracted from the dirt in their cocoon-like pods. This unusual adaptation allows them to survive in extensive dry conditions that would be fatal to most forms of water-dwelling life. [Photos: The Freakiest-Looking Fish]

The video, which does not reflect NSF research, was shot by the American nonprofit organization Ghana Mission Fund, according to a description on the NSF website. In the footage, a group of people dig up oblong lungfish cocoons from dry earth, tearing the structures open to reveal the damp and wriggling fish inside.

There are six species of lungfish that fit into three genuses (or "genera"), and they are currently found in Africa, South America and Australia. Lungfish fossils date back 400 million years, and lungfish are thought to be a common ancestor of all tetrapods — animals with four limbs — researchers wrote in the book "The Biology of Lungfishes" (CRC Press, 2016).

Buried lungfish exhibit a behavior known as estivation — a type of dramatically reduced metabolic activity during periods of prolonged heat or dryness, NSF researcher and ichthyologist Prosanta Chakrabarty said in the video. All four species of lungfish in Africa — Protopterus dolloi, Protopterus aethiopicus, Protopterus amphibius and Protopterus annectens — can surround themselves in protective cocoons to keep from drying out, "The Biology of Lungfishes" authors wrote.

During drought conditions, when the lungfish's pools begin to dry up, they burrow into mud and secrete a layer of mucus that hardens into a protective shell, according to the University of California Museum of Paleontology (UCMP). Once inside the cocoon, the fish gulp air using their lungs, and then networks of blood vessels in their swim bladders help to extract the oxygen, UCMP explained.

Lungfish estivation lasts until enough rain accumulates for them to swim again, and they can remain in this hibernation state for up to four years, Chakrabarty said. And estivating, cocoon-encased lungfish brought into a laboratory were kept alive for up to six years, according to "The Biology of Lungfishes" authors.

Along with air breathing, lungfish share something else in common with land animals: walking ability. African lungfish have four slender appendages that aren't quite fins and aren't quite legs, but they can use their scrawny hind limbs to "hop" forward, scientists discovered in 2011. While lungfishes' rudimentary "walking" doesn't get them very far, it suggests that this type of locomotion may have evolved underwater, before animals were completely adapted to living on land.

Original article on Live Science.

Some emergency-medicine doctors want to banish the phrase "dry drowning" because the term doesn't actually refer to any medically accepted conditions.

"Dry drowning" tends to come up in the summer, as it did this June, after a young boy in Texas died several days after swimming and his parents were told it was because of dry drowning.

But terms such as "dry drowning," "delayed drowning" and "secondary drowning" are all incorrect, and can cause unnecessary alarm, according to the American College of Emergency Physicians (ACEP). [10 Ways the Beach Can Kill You]

"There are no cases of completely normal, asymptomatic patients who suddenly die because they went swimming a few days ago," Dr. Rebecca Parker, president of the ACEP, said in a statement yesterday (July 11). "It's time to retire those incorrect terms, because it is inaccurate and incorrect to say a child was initially fine after a water event and then 'dry drowned' a day or a week later."

Parker said media reports of such instances "unduly alarm" parents.

Still, in very rare instances, a person can die as a result of breathing problems several days after being submerged in water. The name for such an occurrence? Drowning.

The definition of drowning is when a person has any type of breathing problems after being submerged in a liquid, said Dr. Howard Mell, an emergency-medicine physician and a spokesperson for ACEP. For example, if a person goes underwater and comes up sputtering a bit, that's technically drowning, Mell said.

When most people think of drowning, they imagine a person going underwater and never coming up again because he or she dies from a lack of oxygen, Mell told Live Science. But "that would be the far end of the spectrum," he said. The medical term "drowning" includes a wide range of scenarios, including deadly problems, but also milder ones.

Drowning doesn't mean dying, he added.

In the mildest cases, drowning is when water "goes down the wrong pipe," but this phrase is also inaccurate, Mell noted. What's really happening is that water gets to the back of the throat and comes into contact with the epiglottis, which is the flap of cartilage in the back of the throat that blocks the breathing tube when you swallow. The muscles around the epiglottis then spasm to protect you from inhaling water. A person may cough and clear out the water, and then have no further problems.

"If you are symptom-free, it's no longer drowning," Mell said. "It's not going to come back."

The bigger concern is when a person is coughing when he or she comes out of the water and doesn't stop coughing, Mell said. This could indicate that a person did inhale water — in other words, that water got past the protective barrier of the epiglottis, and into the lungs. [10 Bizarre Diseases You Can Get Outdoors]

When even a drop or two of water gets into a person's lungs, it can cause problems, Mell said. This is because the water can wash away a compound called "surfactant" that coats the inside of a person's lungs. Surfactant is a slippery substance that helps keep the air sacs within the lungs open so that oxygen and carbon dioxide can be exchanged between the air sacs and nearby blood vessels. If the surfactant washes away, the immune system may react, leading to a deadly condition called acute respiratory distress syndrome.

If a person inhaled water, and some of the surfactant was washed away, the signs of this would be clear, Mell said. A person would come out of the water coughing, or start coughing within a couple of minutes, he said. An hour later, the cough would be horrid, and an hour after that, the person would be losing their normal color, and turning gray.

The term "dry drowning" came about because there were cases in which people died from this process, but they died several days after they inhaled water, Mell said. "It was harder for people to comprehend" the concept that people can die of drowning when they're not in water, even if they had been coughing and sputtering since they were in the water, he said.

"It's not a benign, mysterious process; it's an obvious process" that starts right away, not several hours or days after a person gets out of the water, Mell said.

There's no process that would be considered "drowning" that would start only several hours after a person was out of the water, Mell added. So if a child develops a cough a few days after swimming, that's just a cough.

But if the person is coughing when he or she comes out of the water, and that coughing continues and gets worse, the person definitely should be taken to the emergency room, Mell said.   

In addition to the ACEP, these organizations also discourage the use of terms such as "dry drowning" and "secondary drowning": The World Health Organization, the International Liaison Committee on Resuscitation, the Wilderness Medical Society, the International Lifesaving Federation, the International Conference on Drowning, the American Heart Association, the American Red Cross and the Centers for Disease Control and Prevention. 

Originally published on Live Science.

Cigarette smoke can have wide-ranging health effects on the body, and the lungs and airways are two of the hardest-hit areas.

But the good news is that after a person quits smoking, the lungs can heal to a certain extent, said Dr. Norman Edelman, a senior scientific advisor for the American Lung Association and a specialist in pulmonary medicine.

As soon as a person inhales the chemicals found in cigarette smoke, the lung's delicate lining becomes inflamed and irritated. For several hours after the individual smoked, the tiny hairs called cilia that line the lungs slow down their brush-like movement. This causes them to become temporarily paralyzed and less effective at cleaning out mucus and other substances, such as dust particles, from the airways.  

Another change observed in the lungs of smokers is an increase in the thickness and production of mucus. Because cilia cannot sweep mucus out of the lungs as quickly as it's being formed, it accumulates in the airways, clogs them up and triggers a cough. A buildup of mucus can also cause more lung infections, such as chronic bronchitis. [Kick the Habit: 10 Scientific Quit-Smoking Tips]

How lungs heal

Generally speaking, some of the short-term inflammatory changes to the lungs can be reversed when people quit smoking, Edelman said. In other words, swelling subsides on the surface of the lungs and airways, and lung cells produce less mucus, he said. New cilia can grow, and these are better at clearing out mucus secretions, he added.

In the days to weeks after quitting, former smokers will notice that they have less shortness of breath when they exercise, Edelman told Live Science. It's not exactly clear why this happens, but part of it stems from getting carbon monoxide out of the blood, he said. This gas found in cigarette smoke can interfere with the transport of oxygen, because carbon monoxide binds to red blood cells in place of oxygen. This may account for the breathlessness some smokers experience.

Another reason former smokers have improved breathing is because the inflammation decreases in the lining of their airways; this happens because the lining is no longer exposed to smoke's chemical irritants, Edelman said. This reduced swelling makes more room for air to flow through the passageways.

Paradoxically, former smokers may cough more during the first few weeks after they quit than when they were smoking. But this is a good thing; it means the lung's cilia are active again, and these fine hairs can now move excess mucus secretions from the lungs into the airways and toward the throat, where they can be coughed up, Edelman said.

"Coughing is cleaning up the gunk in the lungs," Edelman explained.

Another health benefit of quitting is a reduced risk for lung cancer, he said. The longer that former smokers go without lighting up, the lower their risk of getting this cancer, although the risk never completely goes away, Edelman said.

For example, 10 years after quitting smoking, a former smoker's odds of getting lung cancer are about half that of a smoker, according to the Centers for Disease Control and Prevention. But an ex-smoker is still more likely to die of lung cancer than someone who has never smoked.

Not all changes are reversible

The body is very good at repairing some of the damage to lung cells and tissues caused by smoking, but not all of the damage is reversible.

Damage to the lungs and a deterioration in lung function are directly related to the number of packs of cigarettes a person typically smokes per day times the number of years the person has smoked, a measure known as "pack years," Edelman said. The greater the pack years, the more likely the lungs will have irreversible damage, he noted.

Although the lungs have ways to protect themselves from damage, these defenses are reduced with long-term exposure to the harmful chemicals inhaled from cigarettes. As a result, lung tissue can become inflamed and scarred from smoking, and so the lungs lose elasticity and can no longer exchange oxygen efficiently.

Long-term smoking can lead to emphysema, a type of chronic obstructive pulmonary disease (COPD). This condition destroys a portion of the lungs known as the alveoli, which is where the exchange of oxygen and carbon dioxide takes place, Edelman said. People with COPD have shortness of breath and difficulty breathing. 

Once a person's lungs are damaged to the point of emphysema, the walls of the airways lose their shape and elasticity, making it difficult to push all the air out of the lungs. These lung changes are permanent and irreversible, Edelman said

Using MRI imaging, scientists have recently learned that the damage to airways linked with emphysema begins a few years after a person starts smoking, although symptoms of the disease may not show up until 20 to 30 years down the road, Edelman said.

But it's never too late to quit smoking, and quitting at any age can help people breathe better and increase their life expectancy, Edelman said.

Originally published on Live Science.

An elderly woman in Florida had oil in her lungs — for decades — from a now-outdated procedure she received in her 20s to treat tuberculosis (TB), according to a new report of the woman's case.

The 86-year-old woman went to the doctor because of a burning pain in her chest and upper stomach. She was diagnosed with acid reflux, and her symptoms got better after she started treatment for the condition. But while she was at the hospital, she received a chest X-ray that showed something unusual: There was an opaque, cloudy area in the upper part of her left lung.

This cloudy area was concerning to her doctors, because it could have meant that she had fluid buildup in the space between her chest wall and her lung, known as the pleural cavity. In people with certain conditions, blood or pus can accumulate in this area.

However, the woman remembered having oil injected into her lungs decades earlier, as a treatment for tuberculosis. This procedure was called oleothorax, and it was abandoned in the 1950s after effective antibiotics for TB were discovered, said Dr. Abhilash Koratala, an assistant professor of medicine at the University of Florida, who treated the woman and co-authored the report of her case. [27 Oddest Medical Cases]

Given that more than 60 years have passed since this treatment was used, it's rare to see patients today with oil in their lungs from oleothorax, Koratala told Live Science. What's more, most patients who received the oil treatment eventually had the oil suctioned out of their lungs. But some patients never went back to the doctor to have the oil removed, because they were no longer experiencing symptoms from their tuberculosis, as was the case with this patient, the case report said.

The woman didn't give a specific reason for not getting the oil removed, but "it's not uncommon for patients to not go back to the doctor if they are feeling good," Koratala said.

The idea behind oleothorax was to use injections of oil, such as vegetable or mineral oil, to collapse the lung affected by TB bacteria, Koratala said. In the 1930s to 1950s, doctors thought that such "collapse therapy" would give part of the lung a chance to rest, and help kill TB bacteria, according to the Museum of Health Care at Kingston in Ontario, Canada.

When oil is injected into the pleural cavity, blood vessels and lymphatic vessels in the area initially absorb some of the oil, Koratala said. At the time the treatment was in use, doctors often had to "refill" this part of the lung with oil until it collapsed, he said. But over time, the membranes in the cavity would stop absorbing oil, probably because of damage to the tissue caused by the oil, Koratala said. This allowed the oil to remain in the pleural cavity, keeping the lung collapsed. After many years, some deposits of calcium would occur in the area, and the oil mass would stabilize, Koratala said.

The finding of oleothorax in this patient was accidental; it wasn't causing her any symptoms, and it wasn't related to her acid reflux, the doctors said.

Because the woman's condition was stable, there was no need to perform a procedure to take out the oil now, Koratala said. The risks of such a procedure would outweigh the benefits for this patient, and the calcification in the area would make it difficult to remove the oil, he said.

Although the upper part of the woman's lung remains collapsed by the oil, the rest of the lung is fine and can still function, Koratala said

But it's important for the woman and her doctors to be aware of the condition, because some patients experience complications from oleothorax, including infection or expansion of the area, which can cause breathing problems, Koratala said.

"We have to be aware of the complications of oleothorax so that we treat them in an appropriate and timely manner," Koratala said.

And even though this condition is rare, it's also important for doctors to keep it in mind, in order to avoid treating patients unnecessarily when they don't have symptoms, Koratala said. In some cases, doctors who have seen patients who underwent oleothorax have suspected that the patients had lung cancer, and preformed unnecessarily biopsies of the lung, he said.

The report was published March 23 in the New England Journal of Medicine.

Original article on Live Science.

Colds and the flu may take a bigger toll on women than men, according to a new study based on people's reports of their own symptoms.  

The women in the study were more likely than the men in the study to report severe fatigue and muscle aches when they had a cold or the flu, according to the findings, presented in New Orleans last month at IDWeek 2016, a meeting of several organizations focused on infectious diseases. The findings have not been published in a peer-reviewed journal.

In addition, women's severe symptoms lasted longer than men's, according to the study participants' self-reports, the researchers found. [7 Absolutely Horrible Head Infections]

In the study, the researchers compared self-reported cold and flu symptoms in 777 men and women who were seen between 2009 and 2014 at five military treatment facilities across the U.S., said study co-author Dr. Robert Deiss, a research physician with the Infectious Disease Clinical Research Program, a program of the Uniformed Services University of the Health Sciences. The people in the study were either on active duty in the military or were family members of people in the military, he said.

When the patients first went in for treatment, a health care worker took a nasal swab to determine what type of infection they had, and asked the patients about the symptoms they'd had since they became sick. The participants were also asked to start keeping a diary of their symptoms and the severity of those symptoms on a scale of 0 to 3, with 0 indicating that they did not have the symptom, 1 indicating mild symptoms, 2 indicating moderate symptoms and 3 indicating severe symptoms, according to the study.

The symptoms included lower-respiratory symptoms, such as coughing, difficulty breathing and chest pain; upper-respiratory symptoms, such as earaches, runny nose, sore throat and sneezing; and "systemic" symptoms, which included fatigue, headache and muscle aches.

The researchers found that infections from Enterovirus, coronavirus (both of which can cause colds) and influenza virus were common among the participants. They also found that the different types of viruses infected men and women at about the same rates, Deiss said. [Flu Shot Facts & Side Effects (Updated for 2016-2017)]

However, women were more likely than men to report moderate or severe earaches, headaches and reductions in appetite when they first went to the doctor, the researchers found. Women were also more likely than men to report severe symptoms of fatigue and muscle aches. 

But the researchers also found that men and women reported similar levels of symptom severity when they looked back at their first few days of being sick, Deiss said. It wasn't until the third day of being sick that men and women reported differences: From this point on, women were more likely than men to continue to report severe symptoms, he said. [7 Health Woes Brought on by Winter]

Because the symptoms were self-reported, it's unclear if some people minimized their symptoms while others overemphasized them, Deiss noted. What the researchers can conclude from the study is that there seems to be a difference in how men and women report their symptoms, he said.

In the future, the researchers hope to look at the biological differences in cold and flu symptoms in men versus in women, Deiss said. Hormonal differences may play a role in how the immune system responds to these viruses, he said.

Originally published on Live Science.

An elderly woman in Seattle died from an infection that she appears to have contracted from a horse she rode, according to a new report.

The 71-year-old woman had visited her daughter, who operates a horse boarding and riding center in King County, Washington, the report said. During the week of Feb. 21, 2016, one of the horses developed nasal and eye discharge, suggesting the animal had an infection. The daughter treated the horse with antibiotics, and the animal recovered.

But that same week, the daughter developed a mild sore throat and cough, and her mother also showed symptoms of an upper respiratory infection. Both the mother and daughter had been in close contact with the horse, with the mother petting and riding the horse on at least two days, Feb. 25 and 29.

A few weeks later, on March 2, the mother experienced vomiting and diarrhea, and was later found unconscious. She was taken to the hospital, but died on March 3, the report said. [10 Deadly Diseases That Hopped Across Species]

Officials collected a nasal swab from the previously sick horse, along with a swab of the daughter's throat and samples of the mother's blood. All three samples tested positive for the same strain of bacteria, called Streptococcus equi subspecies zooepidemicus (or S. zooepidemicus for short.) This type of bacteria is known to infect animals, including horses, pigs and cats.

It's rare that people get sick from S. zooepidemicus, the report said. When infections in people do occur, they can cause a variety of symptoms, including chills, weakness, difficulty breathing, fever, kidney inflammation and arthritis.

People can become infected with S. zooepidemicus by consuming unpasteurized dairy products. But the daughter said that she and her mother hadn't consumed any unpasteurized dairy products, nor did they have contact with other animals, except one healthy cat.

"[The] evidence from this investigation linked a fatal S. zooepidemicus infection to close contact with an ill horse," the report said.

The mother may have been at increased risk for infection because of her age. It also remains unclear if the woman's respiratory symptoms preceded or followed her infection with S. zooepidemicus. (It's possible that the respiratory symptoms were from a separate infection, which in turn could have made the woman more vulnerable to S. zooepidemicus, the report said.)

The researchers recommend that people thoroughly wash their hands after contact with horses or other animals.

More research is needed to better understand factors that put people at risk for catching S. zooepidemicus from animals, as well as the different symptoms people who get infected can experience, the report said.

The report is published in the Aug. 5 issue of the journal Morbidity and Mortality Weekly Report, from the Centers for Disease Control and Prevention.

Original article on Live Science.

How many times per day do you sigh? Chances are, the number in your head is off by a factor of about 10, according to a new study.

People actually sigh about 12 times every hour, or once every five minutes, researchers found. But these audible exhalations don't necessarily signal tiredness or exasperation. Rather, physiological sighs are vital to keeping the lungs functioning properly, the scientists said.

Now, researchers from the University of California, Los Angeles (UCLA), and Stanford University have identified the source of sighing, which they classify as a life-sustaining reflex that prevents air sacs located in the lungs, called alveoli, from collapsing. [15 Weird Things Humans Do Every Day, and Why]

"A human lung has as much surface area as a tennis court, and so that's all folded inside your chest," study co-author Jack Feldman, a professor of neurobiology at UCLA, told Live Science. "The way that nature did it is that there's 500 million little air sacs called alveoli. And each alveolus is a little sphere, about 0.2 millimeters [0.008 inches] in diameter."

These tiny, round sacs help ensure that sufficient amounts of oxygen can pass easily into the blood through the lung membranes, and Feldman described them as being similar to "wet balloons."

"Did you ever try blowing up a wet balloon? It's very difficult, because the water on the inside sticks together," he said. "This is what happens when an alveolus collapses … and whenever they collapse, that surface area gets taken out of the ability to exchange gas."

In other words, if humans weren't able to sigh, the alveoli wouldn't be able to reinflate, and the lungs would fail. Feldman said the only way to pop alveoli open again is to take a deep breath, which humans tend to do every 5 minutes.

"In the early days of using mechanical ventilation like iron lungs, people were inflated just with normal lung volumes, and a lot of them died because their alveoli collapsed," Feldman said. "Now, when you see someone getting respiratory therapy on a ventilator, you'll notice that every couple of minutes, there's a huge breath that is superimposed, and that is playing the role of a sigh."

So, a sigh is like a double breath, Feldman said, and it doesn't necessarily have to be a loud exhale like you might do when you're huffing or expressing relief. [Gasp! 11 Surprising Facts About the Respiratory System]

However, Feldman said that sighs are actually associated with emotions in a different way, because sigh rates tend to go up when someone is stressed. One of the things that happen to a body under stress is that the brain releases molecules known as peptides, which are protein subunits. Some of these are called bombesin-related peptides.

Bombesin isn't present in mammals, the researchers said, and is actually a toxin found in the skin of a European fire-bellied toad. However, mammals have receptors for it, and previous research found that peptides called  neuromedin B (NMB) and gastrin-releasing peptide (GRP) are the equivalent in mammals, including humans.

Feldman's own previous research identified that injecting bombesin into an area of the brain called the pre-Bötzinger complex increased the sigh rate of rats from 25 times an hour to about 400, while their breathing rate stayed more or less the same.

In comparison, when a special toxin that can kill cells that express the receptor for bombesin was injected into the same area, the animals stopped sighing altogether but continued to breathe normally otherwise, the researchers said.

In the new study, Feldman collaborated with Mark Krasnow, a professor of biochemistry at Stanford University, and his research team. Krasnow had been supervising a Stanford student named Kevin Yackle, who was inspired by a talk Feldman gave about how the brain controls breathing. Yackle went to Krasnow with his idea to go through an online database of 14,000 molecules of the brain and use it as a way of trying to piece together how the nervous system works.

Krasnow and his team were keen to collaborate with Feldman when they realized that he had been simultaneously researching bombesin-related peptides. The Stanford team had identified two molecules, NMB and GRP, that were highly concentrated in regions of the brain that are important for breathing but are found almost nowhere else in the brain. At the time, the researchers didn't know what these molecules were for, but by teaming up with Feldman, the scientists were able to analyze around 14,000 gene expression patterns in the brain cells of mice. They identify around 200 neurons in the mouse brain stem that are responsible for producing and releasing bombesinlike peptides.

"We identified about 400 neurons [in] total that were key for triggering sighs," Feldman said. "That's not a lot of neurons to be involved in a fundamental behavior."

The researchers think their findings could offer insight into other parts of the nervous system and into the mechanisms that may underlie more complex behaviors in humans.

But when it comes to researching the nervous system, it can be a bit like learning a language, Feldman said.

"It's a little bit like saying, 'If you want to understand the English language, do you start with Shakespeare, or [do] you start with Dr. Seuss?" he said. "The vocabulary is simpler, the number of words [is] simpler, but there are a lot of fundamental principles involved in Dr. Seuss that are going to tell us a lot about Shakespeare."

And when it comes to learning Shakespeare, "we have to increase the vocabulary, the sophistication … but it builds on a foundation," he added.

The research could have potential applications for the development of medicine to treat certain conditions, the researchers said. With some anxiety disorders, for instance, people may sigh too much, which can be debilitating. And some people don't sigh enough, which can lead to breathing problems and compromised lung function, the scientists said.

Feldman said he wants to do further research on what individual neurons are doing when a person sighs, and he is interested in breaking down how these neurons are organized.

"An immediate question is, when you apply these peptides in normal inspiratory, bursts become a sigh; a double burst," he said. "Why? What's happening to the neurons? What's happening to the circuit? You don't know. That's a fundamentally important question, not just for sighs but for understanding how the nervous system is transforming information and processing signals."

The research was published online Feb. 8 in the journal Nature.

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A vaccine that protects against the virus that causes Middle East respiratory syndrome (MERS) has been shown to be effective in camels, a new study finds.

The vaccine, which was developed by German scientists, reduces the amount of the virus found in the camels infected with the disease, according to the study.

Camels are considered the primary host for the virus, said the study, published today (Dec. 17) in the journal Science. Humans can catch the disease by coming in contact with a sick camel, the researchers wrote. To date, there have been more than 1,600 cases of MERS in 26 countries since the disease first emerged in 2012, according the World Health Organization. Among these cases, nearly 600 people have died from MERS. [8 Things You Should Know About MERS]

An earlier study found that the majority of camels in Saudi Arabia, where the virus was first identified, had been infected with the MERS virus. 

Vaccinating camels against the virus might reduce its spread from camels to humans, the researchers wrote in their study. As with humans, camels sick with MERS develop upper respiratory symptoms.

In the study, the researchers gave four camels the vaccine using a nasal spray, while four other camels received a placebo. Three weeks later, all of the camels were given the MERS virus.

Eight to 10 days later, the camels who received the placebo spray were plagued with runny noses, but the vaccinated camels were not, the study said.

The researchers also tested samples taken from the camels' respiratory tracts for the presence of the virus. Results showed that the levels were significantly reduced in the camels that had been vaccinated compared with the camels in the placebo group, the study said.

The researchers noted that the vaccine also protects the camels from the related virus that causes camelpox, which is similar to smallpox in humans and can be deadly in the animals.

It's unclear at this point if the same vaccine used in the camels would be effective in humans; however, clinical trials may be on the horizon, the researchers said. 

Follow Sara G. Miller on Twitter @SaraGMiller. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

Before the dinosaur age, the coelacanth — a hefty, mysterious fish that now breathes with its gills — sported a well-developed lung, a new study finds.

This lung likely helped the fish survive in low-oxygen, shallow waters hundreds of millions of years ago, the researchers said. During the Mesozoic era, more commonly known as the dinosaur age, it's likely that some species of coelacanth (see-leh-kanth) moved to deeper waters, stopped using their lungs and began relying exclusively on their gills to breathe, the researchers said.

This adaptation to deep water likely helped coelacanths survive the asteroid that slammed into ancient Earth and killed the nonavian dinosaurs, the researchers said. The fish's gill- and lung-breathing relatives were not as lucky; during the Late Cretaceous period, about 66 million years ago, coelacanths living in shallow waters disappear from the fossil record, they said. [See Images of Modern and Fossil Coelacanths]

The hulking 6.5-foot-long (2 meters) fish has long baffled scientists. Fossils of the predatory fish date back to the early Devonian period, about 410 million years ago. The fish was thought to have gone extinct after the dinosaur-killing asteroid hit Earth, but living coelacanths were discovered off the coast of South Africa in 1938.

Today, there are two known species of living coelacanths that live in the deep waters near Mozambique and Indonesia. Scientists have collected and preserved entire specimens of these fish (which give birth to live young) over the decades, allowing researchers to study how the fish change from embryos to adulthood. 

In the new study, researchers examined the curious lungs of one species of coelacanth (Latimeria chalumnae) at five different stages of growth. They scanned each specimen with X-ray tomography, a method that allows researchers to take multiple X-rays of an object, compile them and create a 3D image.

"Our results demonstrate the presence of a potentially functional, well-developed lung in the earliest known coelacanth embryo," the researchers wrote in the study. However, as the embryo grows, its lung development slows, and it eventually becomes a vestigial (functionless) organ in the fish, they observed. 

Interestingly, adult L. chalumnae have small, hard, flexible plates scattered around their vestigial lungs. It's possible that these plates are similar to the "calcified lung" of fossil coelacanths, said Paulo Brito, one of the study's researchers and a professor of zoology at Rio de Janeiro State University in Brazil.

"In fossil coelacanths, these plates surrounding the lung most probably had a function in lung volume regulation, moving over each other to accommodate volumetric changes," Brito told Live Science in an email. "In extant [living] coelacanths, it represents a rudimentary anatomical structure."

It's possible that the lung became less developed as the coelacanth moved to deeper waters, but remnants of it still exist as a vestigial organ, the researchers said. However, as the lung shrank and became useless, a fatty organ that the fish uses for buoyancy control in deep waters grew and took over the space once occupied by the lung.

"Although we cannot know whether the fatty organ ever existed in fossil forms, due to its unique soft-tissue constitution, this organ in Latimeria has a function in buoyancy control," the researchers said in the study.

Given that the coelacanth has evidence of "calcified lungs" in the fossil record, as well as a developing lung early in its embryonic development, it's possible that the "lung is a primitive character[istic] in bony fishes," Brito said. Lungs are also present in most ancient ray-finned fishes (a subclass of boney fishes), lungfishes and living lobe-finned fish (such as the coelacanth), as well as four-legged vertebrates, including amphibians, reptiles, mammals and birds.

The new findings were published online today (Sept. 15) in the journal Nature Communications.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Like its modern-day descendants, an ancient big fish known as a coelacanth had gills, but it also sported a well-developed lung, according to a new study. An examination of present-day coelacanths shows that they develop lungs as embryos, but the organ soon becomes vestigial, an adaption that allows the fish to live in deep water and breathe solely with the gills. [Read the full story on the coelacanths]

Creatures' features in 3D

This image shows 3D reconstructions of the pulmonary complex of one species of coelacanth (Latimeria chalumnae) at different ontogenetic stages. (Credit: Brito et al. Nature Communications.)

An unexpected find

Evidence of lung anatomy in L. chalumnae. An internal view of the esophageal wall showing an opening between the esophagus and the lung in L. chalumnae (A); a dissected adult lung (B); a microscopic view of a thin slice of the vestigial lung tissue (C). The scale bar equals 0.2 inches (0.5 centimeters). (Credit: Brito et al. Nature Communications.)

An odd fish

At 427 feet (130 meters) underwater, off Sodwana Bay in South Africa, the extant coelacanth L. chalumnae swims in its natural environment. (Credit: Laurent Ballesta / Andromede Oceanology Ltd / http://www.blancpain-ocean-commitment.com/en-us#!/home.)

Extant, not extinct

The extant coelacanth in its natural environment. (Credit: Laurent Ballesta / Andromede Oceanology Ltd / http://www.blancpain-ocean-commitment.com/en-us#!/home.)

A coelacanth specimen

An adult specimen of the extant coelacanth after dissection. The specimen is kept in the Collection of Comparative Anatomy of the Muséum national d’Histoire naturelle in Paris, France. (Credit: Cupello personal archive/ Muséum national d'Histoire naturelle, Paris.)

They were hooked

An international team of scientists studied the new fossil. Here, the researchers are pictured outside the Platform AST-RX of the Muséum national d’Histoire naturelle in Paris. (Credit: Cupello personal archive/ Muséum national d'Histoire naturelle, Paris.) 

A view into the past

Study co-researcher Paulo Brito created a giant replica of the fossil Coelacanth Mawsonia. (Credit: Didier Dutheil personal archive/ Muséum national d'Histoire naturelle, Paris.)

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. 

Surgeons who were treating an infant girl likely had a light-bulb moment of their own when they realized the object they had just retrieved from the girl's windpipe was a light-emitting diode (LED) bulb she had inhaled.

The doctors had originally guessed that the item inside the 15-month-old girl's chest was her grandmother's hairpin, but the U-shaped object seen on the child's chest X-ray turned out to be an LED bulb, perhaps from one of the toddler's toys, according to a new report of the girl's case published online Aug. 26 in the journal BMJ Case Reports.

The object had lodged at the end of the girl's windpipe, close to the main passageway leading into her right lung, said Dr. Kenneth Wong, a pediatric surgeon at Queen Mary Hospital in Hong Kong, who co-authored the case report. An object in this location can block a young child's airway, and become a life-threatening medical emergency, he said.

Children between ages 1 and 3 are particularly vulnerable to swallowing small objects because they have a tendency to put things in their mouths, and may not have teeth capable of chewing the object before it slides down their throat, according to the case report. In addition, a reflex that normally protects young children's upper air passage may not be fully developed in infants. [9 Weird Ways Kids Can Get Hurt]

The girl was brought to the hospital emergency room in January 2012 because she was having trouble breathing, according to the report. Ten days earlier, she had developed a cough that lasted for a week, but she had no runny nose or fever.

Her pediatrician diagnosed her as having a cold and prescribed cough medicine to ease her symptoms. But after regularly taking the medicine for three days, the 15-month-old had become increasingly short of breath.

A chest X-ray revealed the object lodged near her right main bronchus. Judging by the image's shape and size, the child's grandmother suggested it could be a hairpin that she had recently lost.

Seeing the light

To get a better glimpse of the object, the doctors performed a procedure known as a rigid bronchoscopy, in which a long, lighted tube is inserted into the child's nose or mouth, allowing doctors to see inside the throat and lungs.

They saw two metal wires.

The doctors used forceps to remove one of the metal wires, but had more difficulty withdrawing the second. Eventually, they identified both objects as parts of an LED bulb.

The girl had inhaled the LED intact, Wong said. But the bulb got stuck as surgeons were attempting to retrieve it, so they had to take it out in pieces to minimize the damage to her airway, he said.

The girl's persistent cough had been a side effect of swallowing the LED bulb, and her shortness of breath resulted from the bulb obstructing her breathing, Wong told Live Science.

After the procedure, the young girl stayed for two days in the hospital to receive chest physiotherapy, which involved breathing and coughing exercises designed to help remove saliva and mucus from her respiratory tract. She was sent home with a prescription for a two-week course of antibiotics to prevent a chest infection.

Doctors last saw the toddler after she had finished taking her antibiotics, and she was in excellent condition with no sign of any long-term complications, Wong said.

Although cases like the girl's are rare — there have been only two other cases of accidental swallowing or inhaling of LED bulbs reported in the medical literature — LED bulbs can be a safety hazard for young children, especially as the use of them becomes increasingly popular in kids' toys and around the home, Wong said.

And the plastic component of the LED bulb is hard to detect on a chest X-ray, making it even more difficult for doctors to correctly identify a bulb if a child has swallowed one, the report said.

Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

When dolphins dive deep below the water's surface, they avoid succumbing to decompression sickness, or "the bends," likely because the massive sea creatures have collapsible lungs, a new study finds. These lungs allow dolphins to inhale and exhale two to three times quicker than humans.

Understanding how dolphins breathe rapidly and maintain lung functionality under immense pressure could help scientists keep humans safe when they are in similarly extreme situations, such as under anesthesia during surgeries, the researchers said.

Unlike humans, dolphins do not need to be strapped to an oxygen tank to achieve their impressive diving feats. This is because dolphins have compressible lungs that help them withstand high pressures deep in the ocean. [Deep Divers: A Gallery of Dolphins]

"The deeper [dolphins] go into the ocean, the smaller the volume of gas or air in the lungs gets," said study lead author Andreas Fahlman, a professor of biology at Texas A&M University in Corpus Christi. Fahlman found that dolphins can replace as much as 95 percent of the air in their lungs in a single breath. For comparison, humans are capable of replacing only as much as 65 percent. Dolphins exhale and then inhale above water before diving back down with lungs filled with air — each breath consumes and releases a certain amount of oxygen that energizes the animals as they swim the ocean.

The researchers studied six male bottlenose dolphins at Dolphin Quest Oahu, a dolphin training facility in Hawaii that is open to the public. The dolphins were free to swim away from the researchers whenever they wished, Fahlman said, though the animals were trained to sit still and breathe into a mask, called a pneumotachometer. This device essentially functioned as a "speedometer for the lungs," Fahlman said. The mask covered the dolphins' blowholes at the backs of their necks.

When trainers had dolphins breathe as hard as they could, in breaths researchers called "chuffs," the animals could inhale 8 gallons (30 liters) of air in one second, and exhale 34 gallons (130 liters) of air per second. A human's strongest exhale moves at a rate of 4 gallons (15 liters) per second, and human coughs range from about 10 to 16 gallons (40 to 60 liters) per second. In other words, dolphins move air two to three times faster than humans could ever do, Fahlman said.

Clinical applications

Part of the reason dolphins are expert divers is because they can collapse their alveoli, the little sacks on the lungs that monitor air flow, and then open them up again, "but humans can't do that," Fahlman said.

This has implications for humans who are exposed to similarly extreme conditions, such as patients who undergo emergency operations.

"[I]f you're in the hospital and you're undergoing surgery, oftentimes what they do is put a tube down your throat and put a positive pressure to prevent a [lung] collapse from happening," Fahlman said.

Putting positive pressure on the lungs keeps them open, but can also be dangerous, he added. "This is a clinically relevant issue for people in emergency care, for people undergoing surgery, because we cannot as easily open up the alveoli." [The 10 Most Amazing Animal Abilities]

Fahlman said it's possible that dolphins' lungs look completely different from humans' or that dolphins have a very different biochemical composition in their lungs, which could explain their impressive exhalation abilities. Lungs typically contain a compound called surfactant, or pulmonary surfactant, that helps with breathing. Previous research found that surfactant in some seals and sea lions can keep the alveoli more lubricated so they open up easily.

All mammals use surfactant while breathing; it's a "way of trying to reduce the number of calories that it costs [to] inhale and exhale," Fahlman said, adding that animals developed differences in surfactant to adapt to their environments.

Prematurely born babies benefit from surfactant manufactured from cows, Fahlman said, because the babies can't produce enough of the substance at such a young age.

Surfactant from dolphins and other sea mammals could be beneficial under different circumstances, he added. "We can learn about the structure of the surfactant [that animals] have and replicate it for humans," Fahlman said.

Looking to the future

Studying animal breathing rhythms and capacities can also help scientists better understand respiratory disease in marine animals, which is a major cause of morbidity and mortality among marine animals in the wild and under human care, Fahlman said.

Humans are exposed to pollen, debris and other airborne pollutants that many dolphins and other mammals are unable to remove from their blowholes. This can make some animals susceptible to certain diseases like lung disease.

Fahlman said he plans to expand his research to beluga whales and porpoises to investigate their breathing patterns. He said there is especially high concern around mammals living in waters near oil rigs. Researchers are planning to travel to Alaska and the Arctic to study the mammals before oil reserves there are exploited, to establish a baseline for animal health, he added.

Oil spills, like the 2010 Deepwater Horizon catastrophe in the Gulf of Mexico, can severely hurt dolphins' health, though the direct effects of the oil spill can be hard to measure without knowing the animals' health prior to the spill.

"Next time this happens, we will know the health status of the animals in that area, and we can say, 'Well, this was the health status before and this is the health status after,'" Fahlman said.

The study was published July 8 in The Journal of Experimental Biology.

Elizabeth Goldbaum is on Twitter. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science

Mysterious cases of paralysis in U.S. children over the last year have researchers searching for the cause of the illness. Now, a new study suggests that a new strain of a poliolike virus may be responsible for some of the cases.

So far, more than 100 children in 34 states have suddenly developed muscle weakness or paralysis in their arms or legs, a condition known as acute flaccid myelitis, according to the Centers for Disease Control and Prevention. Previously, researchers linked a virus called enterovirus D68 (EV-D68), which can cause respiratory illness similar to the common cold, with some of these cases.

But only about 20 percent of children with paralysis tested positive for EV-D68, and even in these cases, it wasn't clear if EV-D68 was the cause of the child's condition. [Top 10 Mysterious Diseases]

In the new study, researchers say that one case of paralysis, in a 6-year-old girl, is linked with another strain of enterovirus, called enterovirus C105. This virus belongs to the same species (enterovirus C) as the polio virus.

Although the new study doesn't definitely prove that enterovirus C105 was the cause of the girl's paralysis, it suggests that there are other viruses besides EV-D68 that are contributing to the outbreak of acute flaccid myelitis.

The study should make researchers aware that "there's another virus out there that has this association" with paralysis, said study co-author Dr. Ronald Turner, a professor of pediatrics at the University of Virginia School of Medicine. "We probably shouldn't be quite so fast to jump to enterovirus D68 as the [only] cause of these cases," Turner told Live Science.

The 6-year-old girl was previously healthy, but she caught a cold from members in her family, and developed a mild fever. Her fever and cold symptoms soon went away, but she was left with persistent arm pain. Then her parents noticed that the girl's shoulder appeared to droop, and she had difficulty using her right hand, the researchers said.

At the hospital, the girl was diagnosed with acute flaccid myelitis, and a sample from her respiratory tract tested positive for enterovirus C105. This virus was only recently discovered, and the new study is the first report of enterovirus C105 in the United States, the researchers said. The girl tested negative for EV-D68.

Some tests can miss enterovirus C105, because of variation in the virus's genetic sequence, Turner said. This virus may have gone unrecognized in the current outbreak until now because it is relatively new, and can be hard to detect, he said.

"The presence of this virus strain in North America may contribute to the incidence of flaccid paralysis and may also pose a diagnostic challenge in clinical laboratories," the researchers said in their study, which will be published in the October issue of the journal Emerging Infectious Diseases.

The researchers noted that enterovirus D68, and now enterovirus C105, have been found in the respiratory tract of children with acute flaccid myelitis, but so far, these viruses have not been found in the spinal fluid of these patients. That's important because a virus in the respiratory tract would not necessarily cause paralysis.

"You can have a virus in your respiratory tract that’s not doing anything to your nervous system," Turner said.

In order to more definitively link these cases of paralysis with enterovirus, researchers would need to find the virus in the spinal fluid, he said. But so far, tests have not found the virus there.

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Three baby boys with life-threatening breathing problems are alive today thanks to a 4D biomaterial, a medical implant designed to change shape over time, that helped them keep breathing, researchers say.

"Today, we see a way to cure a disease that has been killing children for generations," said Dr. Glenn Green, a pediatric otolaryngologist at the University of Michigan's C.S. Mott Children's Hospital and the senior author of a new report on the boys' cases.

The researchers said that 4D biomaterials could one day help not only patients with respiratory ailments, but also those with disorders involving the heart, bones, muscles or gut.

"The possibilities are really limitless," lead study author Dr. Robert Morrison, a research fellow and resident surgeon at the University of Michigan Health System, told Live Science. [10 Technologies That Will Transform Your Life]

The researchers made the implants using a 3D printer. Three-dimensional printers can create items from a wide variety of materials: plastic, ceramic, glass, metal and even more unusual ingredients such as living cells. The machines work by depositing layers of material, just as ordinary printers lay down ink, except 3D printers can also lay down flat layers on top of each other to build 3D objects.

Advances in 3D printing have enabled the rapid production of medical devices that are customized for individual patients, such as hearing aids, dental implants and prosthetic hands. However, devices made of rigid materials are often unsuitable for young patients who can quickly outgrow the implants.

Recently, scientists began developing techniques to try to accomplish 4D printing, which involves 3D printing items that are designed to shape-shift after they are printed. Green and his colleagues reasoned that 4D items could grow with young patients if needed.

"This is the first 3D-printed implant specifically designed to change shape over time, the fourth dimension, to allow for a child's growth," Green told Live Science.

The three infant boys who were implanted with the new device all had the same life-threatening condition — a severe form of a disease called tracheobronchomalacia, which affects about 1 in 2,000 children around the world. The disease causes the windpipe to regularly collapse, preventing normal breathing. There was no cure, and at the time these children received their implants, their life expectancies were estimated at days to weeks, Green said.

"It is hard to convey how very sick these children were," Green said. All three boys had been in the intensive care unit for months. During that time, to stay alive, they often needed drugs to keep them sedated and prevent them from moving. They all had breathing tubes placed in their necks, and were on artificial ventilators — but still, they sufferedrepeatedly suffered of breathing problems and needed to be resuscitated.

One boy, Kaiba Gionfriddo, was 3 months old when the doctors implanted the new device. Gionfriddo had turned blue when he was a newborn because his lungs were not getting the oxygen they needed. Five-month-old Ian Orbich was unable to have any food in his stomach without suffering cardiac arrests.

Sixteen-month-old Garrett Peterson's airways "were floppy, with the consistency of a wet noodle," Garrett's mother Natalie Peterson told Live Science. "They collapsed pretty much daily, if not multiple times a day. Simple things like changing his diaper or holding him could cause Garrett's airways to collapse. This happened repeatedly for months."

The researchers used CT scans of the infants to develop 3D-printed airway splints whose length, diameter, thickness and other factors were customized for each baby, to help keep the infants' weakened airways open. 

"We can print tens or hundreds of the exact same splint design, no matter how complicated the geometry is," study co-author Scott Hollister, a biomedical engineer at the University of Michigan, told Live Science. "This is very important for quality and design control, because we can take copies or replicas of the exact same splint and test it before we even implant it."

The splints were shaped a bit like hot dog buns, and when they were implanted into the infants and, sewn around their own windpipes, the devices kept surrounding tissue from pushing in and sealing the airways shut. The devicessplints are made of a material called, polycaprolactone, which harmlessly dissolves in the body over time.

"This is the first time 3D printing has been used to create a medical implant for treating a life-threatening disease," Morrison said.

The airway splints were hollow and porous, designed to spread open as the children grew. Green noted that the infants' bronchi, which are the air passages connecting the windpipe with the lungs, were about the width of a pencil lead when the devices were implanted, but will nearly double in diameter by the time the splints dissolve.

The researchers followed the growth of the airways over time with CT and MRI scans. They found the devices improved breathing and expanded to allow the airways to grow in all three patients. All the devices are dissolving as expected, and none of the devices have caused any complications.

The boys are now home with their families. They no longer need sedatives, narcotics or paralytics to keep them breathing. "Holidays are not spent in the hospital anymore," Green said. "Instead of lying flat on their backs for weeks on end, these children are learning to sit and stand and run."

"I honestly don't think we can ever thank Dr. Green and his team in Michigan enough," Natalie Peterson said. "We know that without this procedure, Garrett was a month or so from passing away."

If children with tracheobronchomalacia survive to age 2 or 3, their airways usually grow strong enough to overcome the disorder, and their windpipes eventually will have no signs of the disease that nearly killed them as newborns. The researchers say the airway splints will dissolve slowly enough to help the infants reach this point. The first child to receive the device, Kaiba, has now reached this stage, and "he is doing well after degradation of the splint," Green said.

"Before this procedure, babies with severe tracheobronchomalacia had little chance of surviving," Green said in a statement. "Today, our first patient, Kaiba, is an active, healthy 3-year-old in preschool with a bright future. The device worked better than we could have ever imagined."

"The first time he was hospitalized, doctors told us he may not make it out," Kaiba's mom, April Gionfriddo, said in a statement. "It was scary knowing he was the first child to ever have this procedure, but it was our only choice, and it saved his life."

Garrett is now 2- and- a- half years old. "Garrett's doing awesome now," the boy's father, Jake Peterson, told Live Science. "He's so happy — there's no hint of an issue with his airway splint. He's starting to learn to sit up on his own."

Ian Orbich is now 17 months old, and the researchers say he is known for his grins, enthusiastic high fives and love for playing with his big brother, Owen.

"We were honestly terrified, just hoping that we were making the right decision," Ian's mother, Meghan Orbich, said in a statement. "I am thankful every single day that this splint was developed. It has meant our son's life. I am certain that if we hadn't had the opportunity to bring Ian to Mott, he would not be here with us today."

The doctors received emergency clearance from the FDA to perform these procedures as a last resort. The researchers are now pursuing a clinical trial for the 4D biomaterials for patients with less severe forms of tracheobronchomalacia.

"We've been meeting with the FDA to have a plan set up to have 30 children as part of a clinical trial," Green said. "These will be children that have severe tracheobronchomalacia, but not the imminently life-threatening tracheobronchomalacia of these first three children."

Hollister and Green have filed a patent application related to the device. The scientists detailed their findings online today (April 29) in the journal Science Translational Medicine.

Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

The paranasal sinuses are air-filled cavities that are lined with mucus-making cells. The mucus serves to keep the nose from drying out and to trap contaminants before they reach the lungs.

Mucus (”snot”) is made of water, proteins, antibodies and salts. Its color is an indicator of health:

CLEAR indicates healthy.

WHITE is thick mucus indicating sinus congestion.

YELLOW means that infection-fighting cells are battling a cold.

GREEN indicates that your immune system is fighting a bacterial infection.

RED is blood in the mucus, possibly from broken tissue in the nose.

BROWN could be blood or an inhaled contaminant.

BLACK, unless you're a smoker, could mean a fungal infection.

Ear infections can affect the inner ear or outer ear. There are three main types of ear infections, according to the Centers for Disease Control and Prevention (CDC). The three types are acute otitis media (AOM), otitis media with effusion (OME) and otitis externa, which is better known as swimmer’s ear. Ear infections are most common in children. By their third birthday, three out of four children will have at least one ear infection, according to the National Institutes of Health (NIH).

Risk factors and causes

Certain risk factors or exposures can increase the risk for ear infections, according to Dr. Robert Danoff, a family physician from Aria Health in Northeast Philadelphia and Lower Bucks County, Pennsylvania. These include:

• Age: Children younger than age 3 are more susceptible to ear infections.
• Family history: Children with parents who had frequent ear infections have a higher risk
• Allergies and colds: Stuffy noses may also lead to more frequent ear infections.
• Birth defects and medical conditions: "Patients with Eustachian tube problems and those with other underlying medical conditions such as immune deficiencies or craniofacial anomalies also tend to have more ear infections," Dr. Katie Geelan-Hansen, an otolaryngologist at the Cleveland Clinic, told Live Science. The Eustachian tube is a narrow channel that connects the middle ear with the upper throat.
• Bottle-fed babies or babies who use a pacifier: Babies are especially more susceptible if fed while lying down. They more likely to get ear infections in their first year.
• Weakened immune systems and previous history: Children with an ear infection before six months of age have a higher risk for future ear infections. Persistent fluid behind the ears also makes children more likely to get ear infections.
• Day care: Children in childcare centers are also more likely to get ear infections.

Another element that can make a child more susceptible to ear infections is exposure to cigarette smoke. "Children living in homes or traveling in autos with smokers who are exposed to second-hand smoke are more likely to get ear infections. Second-hand smoke can lead to fluid build-up in the middle ear, resulting in decreased hearing and more frequent ear infections," Danoff told Live Science.

Dr. Aileen M. Marty, a professor of infectious disease at the Herbert Wertheim College of Medicine, agrees. "Yes, parental smoking by one or both parents more than doubles the risk of recurrent AOM infections and how much the parent smokes is important too. In fact, for every additional half-pack smoked there is another doubling of risk of ear infection in the child."

Marty explained that breathing in the toxins from smoke promotes immune cells to react. The reactive immune cells cause swelling of lymph nodes, including those around the Eustachian tube. Then, the swollen lymph nodes compress the Eustachian tube and thereby promote middle ear infections.

Otitis media is an infection of the middle ear, the area right behind the ear drum. It usually occurs when a cold or an upper respiratory infection introduces bacteria into the ear through the Eustachian tube. "Contrary to popular opinion most ear infections are caused by viral infections not by bacteria," Marty told Live Science. The viruses that are the most commonly the initial cause of ear infections include respiratory syncytial virus, adenovirus and cytomegalovirus.

Swimmer's ear is an infection of the outer ear and ear canal due to bacteria growing in a wet, dark environment.

Acute otitis media is the most common ear infection, according to the NIH. During AOM, the tube in the inside of the ear is clogged with mucus and fluid, leading to infection and swelling.

Signs and symptoms

The symptoms of the three different types of ear infections are quite similar. Common symptoms of AOM are earache and fever, hearing loss, headaches, drainage from the ear, pain in the ear, and a feeling of fullness in the ear, according to the American Academy of Family Physicians. Children may be too young to describe what's wrong, and as a result may get fussy, cry excessively, have trouble sleeping and have a reduced appetite. Pus or blood might drain from the ear if the ear drum has burst.

Otitis externa has symptoms that are very similar to middle ear infections, though people may also experience itchiness and pain to the outer part of their ear. The pain may also get worse when the person moves, according to the American Academy of Family Physicians. It can lead to a slight amount of clear discharge that can turn yellowish without treatment.

Otitis media with effusion happens when fluid stays trapped in the middle ear. OME may not present any symptoms and will often go away without notice.

Diagnosis and tests

An ear infection can be detected through a simple examination of the ears, throat and nasal passages at the physician's office with a small, lighted instrument called an otoscope, according to the Mayo Clinic. An infected ear may have areas of dullness or redness or there may be air bubbles or fluid behind the eardrum. The doctor may also use a pneumatic otoscope, which can detect how much fluid is behind the eardrum.The doctor will also examine the throat and sinuses and see if the patient has any recent cold or allergy symptoms.

Additional tests may be performed to further confirm the diagnosis and differentiate between AOM and OME, according to the Mayo Clinic. Tympanometry uses sound tones and air pressure to measure how flexible the eardrum is at different pressures. Reflectometry places a small instrument near the ear and measures how sound emitted from the device is reflected back from the ear drum. This allows the doctor to see if there's fluid trapped in the middle ear.

Treatment and medication

Although ear infections are usually caused by bacteria, and antibiotics are often prescribed, neither OME nor AOM should be treated with antibiotics at the initial onset, according to the CDC. In fact, OME usually will not benefit from antibiotic treatment since it can occur after the infection.

Children from two months to 2 years with non-severe illness should be placed on observation for the initial 48 to 72 hours, according to a guideline drafted by the American Academy of Family Physicians and the American Academy of Pediatrics. Antibiotics, specifically amoxicillin, could be prescribed if illness does not improve after the observation period. A standard 10-day course is recommended for younger children and for children with severe illness; whereas a five- to seven-day course is appropriate for children 6 and older with mild to moderate illness.

Unlike OME and AOM, otitis externa will usually require antibiotic treatment, according to CDC guidelines. Corticosteroids can also be used for reducing itching and inflammation. In all types of ear infection, pain relievers like acetaminophen (such as Tylenol) or ibuprofen (such as Advil) can help reduce pain and fever.

Those with recurrent ear infections behind the ear drum and patients with fluid behind the ear drum for a few months are candidates for ear tube placement.  "The ear tubes are an opening in the ear drum so that if fluid or infection develops behind the ear drum it can come out through the tube, Danoff explained.  "Ear tubes also allow air to go behind the ear drum to help prevent the fluid and infections from redeveloping."

Prevention

"The best way to prevent ear infections is to be up to date on the recommended vaccinations, avoid smoking/being around smoke, vigilant hand washing particularly during the cold and flu season," said Danoff.  "Rest and appropriate nutrition are important as well." 

Breastfeeding or the using ventilated bottles have also been found to reduce incidences of AOM. According to a 2009 study in the journal Pediatric Research, breastfed children have more serum antibodies, which can help them fight off AOM. In addition, when a baby is bottle-fed, negative pressure inside the bottle may cause the infant to suck excessively and generate negative pressure within the Eustachian tube, which can encourage AOM.

Otitis externa can be avoided by limiting time spent in water, according to the NIH. After swimming, water should be drained from the ear canal by turning the head to the side and pulling the earlobe in different directions. According to the CDC, cotton swabs should not be inserted into the ear because this can scratch up the ear canal or the wax layer, which can increase the risk of infection. Keeping pools and hot tubs clean with disinfectants and regular pH testing will also reduce the risk of infection.

Additional resources

• Mayo Clinic: Ear Infections
• CDC: Ear Infections
• NIH: Ear Infections
• U.S. Department of Health and Human Services: Ear Infections in Children

The deaths of four children, possibly linked to their infections with enterovirus D68, are still puzzling to experts.

A girl in Rhode Island died last week after she developed both an infection with the enterovirus D68 (EV-D68) and also a rare infection with staph bacteria, according to a report from the Rhode Island Department of Health. Enterovirus D68 is a virus that causes flulike symptoms and has now sickened hundreds of people across the United States.

In addition to the Rhode Island child, workers at the Centers for Disease Control and Prevention (CDC) have found EV-D68 in the samples from several people who died in other states, but it's unclear what role the virus played in those deaths. [Tiny & Nasty: Images of Things That Make Us Sick]

Still, only a small proportion of people with EV-D68 will have symptoms worse than a runny nose, sneezing and a low-grade fever, health officials said.

"We are all heartbroken to hear about the death of one of Rhode Island's children," Dr. Michael Fine, director of the Rhode Island Department of Health, said in a statement. "Many of us will have EV-D68. Most of us will have very mild symptoms, and all but very few will recover quickly and completely. The vast majority of children exposed to EV-D68 recover completely."

But the reasons why some may die while others show very few symptoms remain unclear.

Double infection

The CDC has confirmed cases of EV-D68 in 472 people, most of them children, in 41 states and the District of Columbia. Researchers originally identified the virus in 1962, and it's unclear why there is a sudden spike in its incidence now, health officials said.

EV-D68 symptoms typically look like those of the common cold, but can develop into wheezing and breathing problems. The virus is also in the same family as the poliovirus, and can cause muscle weakness or paralysis in a small percentage of cases, according to recent reports involving several children in Denver.

In the case of the girl in Rhode Island, the staph bacterial infection likely played a role in her death, said Dr. Amesh Adalja, an infectious disease physician at the University of Pittsburgh Medical Center, who was not involved in the Rhode Island child's care. Staph bacteria are common and usually harmless, but can cause infections such as pneumonia, as happened in this case, Adalja said.

"Although [staph] lives harmlessly on a lot of people's skin, when it gets into the lungs, it can cause severe disease," he said. "The consequences can be pretty severe because you're already in the hospital with enterovirus, and now you got a secondary infection, which pushes it over the edge."

In fact, such infections are common in people with respiratory illnesses, Adalja said. For example, during the 1918 influenza pandemic, the majority of people who died were not killed by influenza virus infection, but by secondary bacterial infections, he said.

Immune system factors

Still, it remains unclear why EV-D68 itself is asymptomatic in some people, but causes devastating infections in others. However, it's likely a combination of factors involved with each person's immune system, Adalja said.

"That is something that is on the cutting edge of research, understanding how infectious diseases interact with the immune system and produce different illnesses in different people," he said.

There is no vaccine or treatment against this illness, but doctors recommend several ways to avoid contracting EV-D68. People should wash their hands, avoid touching their faces and help children with asthma manage their symptoms, according to the CDC.

Follow Laura Geggel on Twitter @LauraGeggel and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

An uncommon virus has caused clusters of severe respiratory illness among children in at least two U.S. states, according to the Centers for Disease Control and Prevention.

In addition, 10 other states are investigating possible cases of this virus, the CDC said. Missouri and Illinois reported the clusters, and investigations are taking place in Colorado, Kentucky, Kansas, Iowa, Ohio, Oklahoma, North Carolina, Georgia and other states, according to ABC news. (Two states investigating cases have not been named).

Recently, health officials in Chicago and Kansas City, Missouri, notified the CDC that hospitals in those areas were experiencing an unexpectedly high number of cases of severe respiratory illness, Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, said today in a news conference.

Researchers at the CDC tested samples from some of the sick children, and found that 19 out of 22 samples from Kansas City, and 11 out of 14 samples from Chicago tested positive for a rare virus called enterorvirus D68 (EV-D68), Schuchat said.

Sick children in these clusters ranged in age from 6 weeks to 16 years old, and more than half had a history of asthma or wheezing, Schuchat said. Common symptoms of the hospitalized children included wheezing and difficulty breathing.

Enteroviruses are common viruses that cause a range of symptoms, including coldlike symptoms, fever and rashes. However, there are more than 100 different types of enterovirus, and reports of EV-D68 in the United States are rare, Schuchat said. [7 Devastating Infectious Diseases]

Most people infected with enteroviruses have no symptoms or have mild symptoms, but in some cases, these viruses can cause severe illness. The viruses are more likely to infect children and teens, Schuchat said. So far, no adults have been reported to be sick with EV-D68 in the recent clusters.

Because reports of EV-D68 have been rare, health officials don't yet know the full spectrum of symptoms the virus can cause or exactly how it spreads, Schuchat said. However, officials said they believe it spreads through respiratory secretions, such as when someone coughs, sneezes or touches a surface, Schuchat said.

"We don't know as much as we'd like to know about this virus," Schuchat said.

While most cases of a runny nose won't turn into severe illness, Schuchat said U.S. parents should seek medical attention for their kids if the children experience wheezing or difficulty breathing.

Health care professionals should be aware that clusters of EV-D68 are occurring, and should consider EV-D68 in cases of severe respiratory illness that are not explained by other causes, Schuchat said.

The good news is that, although enteroviruses can cause severe illness, the length of the illness tends to be short, and it very rarely causes long-term health effects, said Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee. "Even on the severe end of the scale, [patients] get better quickly," Schaffner said. So far, no deaths have been reported linked to EV-D68, the CDC said.

Researchers don't yet know how far EV-D68 will spread.

"Enteroviruses are hard to predict," Schaffner said. "It would be unusual for the virus to spread all over the country, but this is an unusual virus, so we'll just have to wait and see."

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

The bacterium that causes Legionnaires' disease — an uncommon kind of pneumonia that can be deadly — can grow in the windshield washer fluid that's used in cars, a new study suggests.

In the study, researchers found that the bacterium Legionella, normally found in freshwater, can survive in car windshield washer fluids and grow in washer-fluid reservoirs. People could become infected with the bacteria when they come in contact with the fluid, the researchers said.

In fact, the bacteria can survive in windshield-washer fluid for anywhere between a few days and several months, depending on the kind of fluid, the researchers said. And, in one particular type of fluid, the bacteria survived longer than they did in sterile water.

"Washer-fluid spray can release potentially dangerous numbers of these bacteria into the air," study author Otto Schwake, a doctoral student at Arizona State University, said in a statement.

Prior to the study, it was known that the bacteria could be present in the mist from air conditioners, hot tubs and showers, among other sources, but scientists hadn't investigated whether the bacteria could live in washer fluid.

Now, "These results suggest that automobiles may serve as a source of transmission for Legionella infections," Schwake said. [5 Things You Should Know About Legionnaires' Disease]

As many as 18,000 people in the United States are hospitalized yearly for Legionnaires' disease, according to the Centers for Disease Control and Prevention. However, most people exposed to the bacteria do not become sick; older people and those with weakened immune systems are more likely to become ill.

In the study, the researchers examined windshield fluid from Arizona school buses and found that, in nearly 75 percent of the buses, the fluid was contaminated with the bacteria.

The researchers measured the levels of the bacteria in washer fluid in a laboratory, and grew samples of bacteria in the fluid.

Although windshield washer fluid is rarely associated with the spread of Legionnaires' disease, previous research found that people who drive may have a higher risk of Legionnaires' disease than people who don't drive. In one study, researchers found that almost 20 percent of cases of Legionnaires' disease in the United Kingdom that were not related to hospitals or outbreaks were associated with car windshield washer fluid.

The high levels of the bacteria that the researchers found in windshield washer liquid may be attributed, in part, to Arizona's warm climate, which provides a good environment for these bacteria to survive, as they thrive in heat.

"While potential transmission of a deadly respiratory disease from a source as common as automobile windshield washing systems is significant, the study also points to the fact people can be exposed to pathogens — particularly those occurring naturally in the environment — in previously unknown and unusual ways," Schwake said.

The study was presented May 18 at the 2014 general meeting of the American Society for Microbiology.

Follow Agata Blaszczak-Boxe on Twitter. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

To date, 538 people have been infected by the Middle East Respiratory Syndrome coronavirus (MERS-CoV). The number of reported cases have dramatically increased since mid-March 2014, according to health officials at the WHO and CDC. 

MERS was first reported in Saudi Arabia in 2012. The virus causes an acute respiratory illness, fever, cough and shortness of breath. Thirty percent of sufferers have died. The virus is passed along through close contact. On May 2, 2014, the first U.S. case of MERS was confirmed in a traveler from Saudi Arabia, who recovered. On May 12, 2014, officials announced a second case, in a person who traveled from Saudi Arabia to Orlando, Florida.

The median age of persons infected is 49 years old. Sixy-nine percent of cases are in males. Ninteen percent of cases are in health-care workers.

The Centers for Disease Control and Prevention recently announced the second case of Middle East Respiratory Syndrome (MERS) in the United States. Here are answers to commonly asked questions about this deadly disease.

What is MERS?

MERS is a respiratory condition caused by a virus that's only recently been seen in humans. Symptoms include fever, cough and shortness of breath. Cases of MERS first appeared in September 2012 in Saudi Arabia, and the virus has since sickened more than 500 people in 14 countries. Close to 30 percent of infected people have died. Most cases have been in the Middle East, particularly in Saudi Arabia. The virus that causes MERS is called MERS coronavirus.

Is MERS the same as SARS?

No. Both MERS and SARS (severe acute respiratory syndrome)belong to the same family of viruses, called coronaviruses, but the two viruses are not the same.

Unlike SARS, which tended to affect younger and healthier people, many people infected with MERS have had underlying chronic conditions, such as diabetes, heart or kidney disease.

Where does MERS come from?

Researchers don't know for sure. The MERS coronavirus has been found in camels in Egypt, Qatar and Saudi Arabia, according to the World Health Organization. But researchers can't say for sure if people caught the disease from camels. For example, it could be that another animal infects both humans and camels. The MERS virus has also been found in bats.

Has MERS come to the United States?

Yes, there have been two confirmed cases of MERS infection in the United States. Both cases were in people who caught the virus abroad and traveled to the United States.

The first case was in a person who traveled from Saudi Arabia to Chicago in late April, and took a bus to Indiana. The patient has fully recovered, and none of the patient's close contacts have signs of MERS.

The second case was in a health care worker who left from Saudi Arabia to travel to Orlando on May 1, and has since been hospitalized. Health officials are notifying and tracking people who had close contact with the patient.

What risks do these two cases pose to the U.S. public? Can you get MERS from public transportation?

Health officials say the risk of MERS to the general U.S. public from the two MERS cases is extremely low. Transmission of MERS appears to require close contact, and most cases of human-to-human transmission have occurred in people who cared for those who were sick.

In both known U.S. cases, the CDC contacted people who were on the same flight as the patient, but an agency spokesperson said this was out of an "abundance of caution."

Has there been an increase in MERS cases lately?

Yes. Since late March, there have been 330 new cases of MERS worldwide, most in Saudi Arabia. Prior to that, there were fewer than 200 cases over the 1.5-year period between September 2012 and February 2014.

What's the reason for the increase? Is the virus mutating?

The reason for the recent increase in MERS cases is not fully understood. A number of the new cases occurred during outbreaks in hospitals, but there has also been a rise in "sporadic" cases, in which patients did not have contact with anyone else who had MERS, according to WHO.

Some of the increase may have been a result of better monitoring efforts, according to Dr. Tom Frieden, director of the CDC, meaning health officials are detecting more cases. Health officials have sequenced the genome of the virus, and so far, it does not appear to be mutating, Friedensaid, speaking at a news conference Monday.

How long does it take to develop symptoms after you've been exposed to the virus?

The time between someone's exposure to the virus and when he or she becomes sick is usually about five days, and 14 days at the most, according to the CDC.

People who develop fever and cough or shortness of breath within two weeks of traveling to countries in or near the Arabian Peninsula should see their doctor, and tell them about their travel history, the CDC says.

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Air pollution exposure contributes to one in eight deaths around the globe, according to estimates released Tuesday (March 25) by the World Health Organization.

More than doubling previous estimates of air pollution-related deaths, the new report says air pollution killed 7 million people in 2012, making it the No. 1 environmental health risk.

Respiratory ailments have long been linked to air pollution, but dirty air also has more insidious effects on health.

WHO officials say they've found a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases; stroke and ischaemic heart disease accounted for a combined 80 percent of outdoor air pollution-caused deaths in 2012.

Air pollution isn't just a threat in major cities like Beijing, where thick layers of smog can sometimes be seen from space. Cooking over coal, wood and biomass stoves can create indoor air pollution, which was implicated in 4.3 million deaths in 2012, according to WHO data. This type of pollution disproportionately affects poor women and children. [In Photos: The World's Most Polluted Places]

"Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves," Dr. Flavia Bustreo, WHO assistant director-general for family, women and children’s health, said in a statement.

The countries hit hardest by air pollution were low-income and middle-income nations in Southeast Asia and the western Pacific region. In those places, a total of 3.3 million deaths were linked to indoor air pollution and 2.6 million deaths were linked to outdoor air pollution, according to the WHO.

"The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes," Dr. Maria Neira, director of WHO's department for public health, environmental and social determinants of health. "Few risks have a greater impact on global health today than air pollution; the evidence signals the need for concerted action to clean up the air we all breathe."

The report drew from 2012 WHO mortality data and new estimates of air pollution exposure levels based on satellite data and ground-level monitoring measurements.

Follow Megan Gannon on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Surprise!

The respiratory system is made up of several organs and structures, including the lungs, windpipe, diaphragm and alveoli. It is responsible for taking in oxygen and expelling carbon-dioxide waste.

Here are 11 surprising facts about the respiratory system.

You lose a lot of water just by breathing.

Breathing allows you to take in the oxygen your cells need and expel carbon-dioxide waste. But when you exhale, you also breathe out a lot of water.

How much water do you lose from breathing?

When at rest, humans exhale up to 17.5 milliliters (0.59 fluid ounces) of water per hour, according to a 2012 article in the journal Polish Pneumonology and Allergology. But you lose about four times that amount when you exercise, the study said.

Some people can hold their breath for more than 20 minutes.

The average time an adult can hold his or her breath is between 30 and 60 seconds. This limitation has more to do with the buildup of blood-acidifying carbon dioxide than the lack of oxygen, which your body stores in muscle proteins called myoglobin.

But free divers — people who practice the sport of diving underwater without using equipment like scuba gear — have different techniques, such as hyperventilation, to decrease the concentration of carbon dioxide in the blood, allowing them to hold their breath for remarkably long times. Denmark's Stig Severinsen currently holds the Guinness World Record for the longest free dive — in 2010, he held his breath underwater for 22 minutes.

The lungs are the only organs that can float on water.

Each of your lungs contains about 300 million balloon-like structures called alveoli, which replace the carbon-dioxide waste in your blood with oxygen. When these structures are filled with air, the lungs become the only organs in the human body that can float on water.

In fact, medical examiners use the so-called "lung float test" during autopsies to determine if a baby was stillborn (died in the womb). If the lungs float, the baby was born alive; if the lungs don't float, the baby was stillborn. This method is accurate 98 percent of the time, according to a 2013 study in the International Journal of Legal Medicine.

Sneeze particles may not travel as fast as people think.

In the past, modeling studies have estimated the velocity of a sneeze at 112 mph (180 km/h). On the popular Discovery Channel series "MythBusters," hosts Jamie Hyneman and Adam Savage recorded a maximum sneeze velocity of 39 mph (63 km/h).

However, a 2013 study in the journal PLOS ONE found that a sneeze's maximum velocity is even lower than the rates determined on "MythBusters." Using a high-speed camera and LED lights, the researchers found that their study participants only sneezed up to 10 mph (16 km/h).

The common cold can be caused by hundreds of different viruses.

The common cold is by far the most prevalent respiratory-system illness, and may be the most common illness known today. It is the leading cause of doctor visits, as well as missed days from work and school, according to the Centers for Disease Control and Prevention. In the United States alone, there are more than 1 billion cases of the common cold each year.

A cold is often thought to be synonymous with "rhinovirus," the virus that most frequently causes this type of illness. But there are actually more than 200 viruses that can cause a cold, including the human coronavirus and the respiratory syncytial virus.

The lungs and windpipe were important symbols in ancient Egypt.

In humans and other animals, the lungs and windpipe must work together to provide the tissues and cells of the body with oxygen. The ancient Egyptians understood the importance of this cohesion for survival, and created a hieroglyph that depicts the lungs attached to the windpipe, to symbolize the unity between upper and lower Egypt that was necessary for the country to be strong and healthy.

Because pharaohs were responsible for ruling over the two lands, the lungs-windpipe hieroglyph is often found on artifacts belonging to pharaohs, including clothing, furniture and jewelry.

Elephants have a unique respiratory structure.

In the respiratory system of mammals, a thin sheet of tissue called the pleura wraps around the lungs and lines the chest cavity. The area between the layers of pleura is known as the pleural space, or pleural cavity, and it contains pleural fluid, which provides lubrication as the lungs expand and contract.

Unlike all other mammals, the pleural cavity of elephants is filled with tough connective tissue. This unusual structure allows elephants to snorkel and withstand the differences in pressure above and below water, without rupturing the blood vessels in the lining of their lungs, according to a 2001 article in journal Respiration Physiology.

Chest movement during breathing isn't the result of air movement.

When you breathe in, our chest swells; when you breathe out, our chest collapses. But these chest movements are not actually the result of air filling up or exiting the lungs.

During inhalation, the diaphragm — a thin sheet of dome-shaped muscle that separates the chest and abdominal cavities — contracts and moves down, increasing the space in the chest cavity. At the same time, the muscles between the ribs contract to pull the rib cage upward and outward. During exhalation, the exact opposite happens.

Asthma was once treated with psychotherapy.

Modern science has shown that asthma is a chronic lung disease that causes the airways to become inflamed and narrowed. It's a physical illness that can be exacerbated by psychological factors.

Between the 1930s and 1950s, however, people thought the roots of asthma were psychological. Therefore, treatments for asthma focused mainly on psychoanalysis. Therapists even interpreted a child's asthmatic wheezing as a suppressed cry for his or her mother, according to a 2005 article in the journal Clinical Practice & Epidemiology in Mental Health.

Horses only breathe through their noses.

For humans, breathing through the mouth comes naturally and easily. The same is true for many other mammals: Dogs, for example, pant to cool off.

Horses, however, only breathe through their nostrils. They have a flap of tissue that forms a tight seal over the oral cavity, which prevents them from breathing through their mouths, even in respiratory distress. When they eat and swallow food, that flap closes off the nasal cavity and opens up the oral cavity, allowing food to go down the pharynx (the upper part of the throat.).

Pulmonary circulation was first described in the 13th century.

Pulmonary circulation is the process by which blood travels from the heart to the lungs and then back to the heart. This flow keeps the heart supplied with oxygen, which the blood picks up from the lungs.

In 1243, the Arab physician Ibn al-Nafis became the first person to describe this complicated process, when he detailed it in his work, "Commentary on Anatomy in Avicenna's Canon."It wasn't until 300 years later that European scholars came to the same conclusion, according to a 2008 article in the Journal of Applied Physiology.

You may think that coming down with a cold or the flu this time of year is inevitable, but there are some things you can do to reduce your risk of illness, experts say.

Here are five tips to prevent the sniffles this holiday season:

Don't touch your face

Although many of us touch our faces without thinking about it, this can spread disease.

"Anytime you touch any of your mucus membranes — your eyes, nose and mouth — these are ways to transmit infection," said Dr. Michael Langan, a primary care physician and assistant professor at The Ohio State University Wexner Medical Center.

If you can avoid touching your face, this may be beneficial, Langan said.

Previous studies have suggested that people contaminate their hands with germs more often than they wash their hands.

Wash your hands

Washing your hands often with soap and water can prevent the spread of germs to yourself and others, according to the Centers for Disease Control and Prevention.

"Nothing is a better substitute for being vigilant about hand-washing," Langan said.

The CDC recommends scrubbing your hands for 20 seconds — about the length of time it takes to sing the "Happy Birthday" song twice.

If you're on the go and can't get to a sink, then alcohol-based hand sanitizers are an adequate way to cleanse your hands, Langan said. But if your hands are visibly soiled, you should wash them, he said.

Get a flu shot

A yearly flu shot is the best way to protect yourself against the flu, according to the CDC. The best time to get a flu shot is in the early fall, before flu activity starts to rise, but it's still not too late to get flu shot this season, the CDC says.

It takes about two weeks for a person to build up immunity against the flu after they get their shot.

You cannot get the flu from a flu shot. The flu vaccine injection contains no live virus, only viral proteins.

Langan noted that flu shots do not protect against colds, so hand-washing and other protective measures are still important.

Avoid sick people

Contact with sick people is sometimes unavoidable, but if you know someone who has the flu or another contagious illness, you should try to limit your contact with them as much as possible, Langan said. This is especially important for people with health conditions that may increase complications from the flu, such as heart disease, liver disease and diabetes, or being pregnant, Langan said.

The Food and Drug Administration says that parents should keep infants away from crowds for the first few months of life to limit their exposure to infected people.

Stay active and practice healthy habits

A healthy lifestyle, including regular exercise, eating healthfully and getting enough sleep, is good for your general well-being, Langan said, and may help keep you from falling under the weather.

The FDA notes that smokers are more prone to respiratory illnesses, and complications from these illnesses, than nonsmokers.

In terms of taking supplements, such as vitamin C, vitamin E and zinc, Langan said there is not much evidence that such herbal remedies work to prevent colds, or reduce the length of cold symptoms.

"There's not a lot of harm in using those products, but there's also not a lot of proven benefit," Langan said.

Follow Rachael Rettner @RachaelRettner. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.

A man who suffered from a bloody cough that persisted for more than a year was surprised to find that the cause was a giant ball of fungus growing in his lung, according to a recent report of his case.

The man, a farmworker in Italy, may have contracted a fungal infection, called aspergilloma, while working in the fields. For a year, he struggled with not only the cough but also fever and weight loss. His symptoms hadn't improved despite several courses of antibiotics, according to the report published Oct. 24 in the journal BMJ Case Reports. 

Aspergilloma, a fungal infection that mainly infects the lungs, is relatively uncommon, and this particular clump of fungus was extremely large, at nearly 3 inches (7.6 centimeters) wide.

"My experience is very large, and it's the biggest I've ever seen," said study co-author Dr. Marcello Migliore, a thoracic surgeon at the University of Catania in Italy.

Aspergilloma enters the lungs through the respiratory tract. It creates a cavity inside the lungs, and then a ball of fungus grows inside that space. The fungus typically infects people with suppressed immune systems or lung problems such as tuberculosis. If left untreated, aspergillomas can cause pneumonia and death, Migliore said. [7 Devastating Infectious Diseases]

When the 42-year-old farmworker, a chronic smoker, initially came to see doctors, he had lost 77 pounds (35 kilograms) over the previous a year. Despite taking antibiotics for several months, the man's symptoms worsened.

A computed tomography (CT) scan revealed a 2.75-inch by 2.5-inch (7 cm by 6.5 cm) "vegetative" mass in the left upper lobe of his lung. Depending on whether the man was lying down or sitting up, the position of the lesion moved.

Still, the doctors didn't know at that point what was causing the cavity, though the CT scans did reveal a suggestive halo around the lesion that is a signature of the fungus.

"When there is a large cavity like that, medical therapy does not do anything, so we must remove it," Migliore told LiveScience. 

When Migliore performed the surgery, he realized it was a large ball of fungus — the biggest he had ever seen. [Image of the fungus]

When the doctors followed up with the man 16 months after the surgery, they found he had improved greatly, and no longer had any troublesome symptoms.

"Now that half of the lung is away, things are going well, he is now happy," Migliore said.

Follow Tia Ghose on Twitter and Google+. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.

A 57-year-old woman in Italy who went to the doctor with inflamed sinuses and facial pain had an unusual diagnosis: a dental implant in the sinus.

The woman had undergone oral surgery about two years before to place an implant — a 2-centimeter long (0.79 inch) metal screw designed to hold in place a replacement for a missing tooth — in her upper jaw. But surprisingly, an inspection of her mouth revealed the implant was not there. Instead, the gums covering the area of her missing tooth were healed, and her remaining teeth were healthy.

A CT scan showed the implant to be in her sinus cavity, next to her left eye. The researchers performed surgery to remove the dental implant, after which the woman's sinus symptoms went away. Eight months later, she remains healthy, according to the report of the case published today (Oct. 23) in the New England Journal of Medicine. [Chew on This: 8 Foods for Healthy Teeth]

The researchers said the implant may have been wound up her sinus because of improper positioning, or as a consequence of tissue around the implant eroding, as well as bone loss.

Study researcher Alberto Schreiber, of the University of Brescia in Italy, said that he suspects the implant had been in the woman's sinus for at least a year, and perhaps even since the patient's surgery two years before.

Previous cases of dental implants ending up in the sinus have been reported, he said. In one case, an implant ended up in the base of the skull, Schreiber told LiveScience.

Dr. Eric Cohen, an ear nose and throat specialist at Lenox Hill Hospital in New York, said that dental implants can migrate if they do not properly integrate into the jawbone. "The bone may have been too thin" for the implant to properly integrate, said Cohen, who was not involved with the woman's case.

Because the roots of upper teeth can extend up into the floor of the sinus, dental implants (which are designed to act as tooth roots) can push into the sinus, and allow bacteria to enter, he said.

On the other hand, Dr. Jack Caton, chair of the Division of Periodontics at the University of Rochester Medical Center, speculated that the implant became displaced during the original surgery to implant it. Caton pointed out that there was no crown attached to the implant, which doctors would have likely added at some point if the surgery was successful.

"The patient may not have been informed of this intraoperative complication by the surgeon, or may not have understood any information that was given," said Caton, who also did not treat the patient.

In his own experience, Caton has seen a dental implant become displaced into the sinus during oral surgery, which doctors then had to surgically remove.

The case report is published today (Oct. 23) in the New England Journal of Medicine.

Follow Rachael Rettner @RachaelRettner. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.

Brushing your teeth, flossing and visiting the dentist keep your teeth and gums healthy, but maintaining good oral hygiene is also important for your overall health, research suggests.

In some cases, oral problems can be a symptom of other diseases, such as diabetes. Research has also linked gum disease to heart disease, premature birth and even knee arthritis.

"The mouth is a portal into the rest of the body," said Dr. Donald Ratcliffe, chairman of the department of dental medicine at Staten Island University Hospital in New York. Growing research shows "there's a relationship between the bacteria — and the inflammation that bacteria cause in the mouth — [and] a lot of other diseases," he said. [5 Experts Answer: Is Flossing Really Necessary?]

Here are several ways that oral hygiene is related to the rest of your health.

Diabetes

One complication of diabetes is gum disease. Diabetes can change in blood vessels in ways that impair blood flow, which in turn, weakens gums and makes them more vulnerable to infection, according to Ohio State University Medical Center. Diabetes also increases blood sugar levels, and if these increases aren't properly managed, high glucose levels in the mouth can encourage bacterial growth.

A 2011 study found that dentists could identify people with diabetes 73 percent of the time based on only a count of their missing teeth and an examination of the abnormal openings between the tooth and gums. If the dentists took into account results from blood tests, the accuracy increased to 92 percent.

More than 7 million people with diabetes don't know they have it, and dentists could play a role in identifying those with the disease, the study concluded.

Heart disease

Several studies have linked periodontal disease, which is a chronic bacterial infection of the gums, with an increased risk of heart attack and stroke.

For example, a 2003 review of nine previous studies found that people with periodontal disease had a 19 percent increased risk of developing cardiovascular disease, compared with people without periodontal disease.

The reason for the link is not clear. Some researchers have suggested that periodontal disease increases inflammation in the body, which in turn, is a risk factor for heart disease. Others have suspected that bacteria from the mouth may find their way into the bloodstream, and contribute to plaque buildup in arteries. A 2005 study from researchers at the University of Florida even found oral bacteria inside artery plaque.

However, it's too soon to say the bad oral health actually causes heart disease. The two conditions share several risk factors, including smoking, old age and diabetes, which may explain why they occur together, according to the American Heart Association. Last year, the AHA said there is no conclusive evidence that gum disease actually causes heart disease, or that dental treatment prevents heart disease.

Still, for some heart conditions, the link between oral health and heart disease is more established. Endocarditis, a condition that involves inflammation of the lining of the heart valve, is most commonly caused by bacteria (including oral bacteria) that enter the bloodstream and travel to the heart. If you have poor oral hygiene, activities such as brushing your teeth may tear the oral tissue, and allow bacteria to enter the bloodstream, according to the Mayo Clinic. But the condition is rare in people with healthy hearts.

Oral health and pregnancy

Studies have linked periodontal disease in pregnant women with an increased risk of preterm birth. While these studies cannot prove that gum infections cause preterm birth, some researchers have speculated that the immune response to such infections might trigger preterm labor.

However, treating periodontal disease does not seem to reduce the risk of early delivery.

A 2011 study from Australia found that women with periodontal disease took longer to become pregnant than those without the condition.

Knee arthritis

A 2012 study suggested oral bacteria may contribute to some cases of knee osteoarthritis and rheumatoid arthritis. The researchers tested the synovial fluid, which is found in the joints, of 36 people with knee arthritis. Five of the patients had gum bacteria in their fluid. For two of the patients, the bacteria found in the joint fluid was a genetic match to bacteria found in the mouth.

Bacteria in the joints could exacerbate arthritis, the researchers said. However, because the study was small, more research is needed to prove that mouth bacteria can cause or worsen arthritis.

Respiratory illness

Bacteria in the mouth may also find their way to the lungs if a person breathes in tooth plaque, Ratcliffe said. This may cause pneumonia or other severe respiratory disease. The risk for this happening is highest in people with underlying conditions, such as conditions that compromise the immune system, he said.

Bacteria in the airways can also worsen chronic lung conditions, such as emphysema, according to the University of Maryland Medical Center.

Full medical history

Often, people might not think about the ways that their oral health affects the rest of their body. In fact, many people neglect to provide their full medical history to their dentist, such as medications they are taking, Ratcliffe said.

"People don't believe that we need to know some of that information, because they don't think it's related to dentistry," he told LiveScience.

For instance, people taking medications for breast cancer, prostate cancer, or osteoporosis may not realize that these drugs affect the ability of bone to heel. "If we do an extraction, the bone may not heel probably," which could result in an infection, Ratcliffe said.

Patients should be educated about the importance of disclosing their medication history to their dentist "so they don't get hurt," Ratcliffe said.

Follow Rachael Rettner @RachaelRettner. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.

The primary organs of the respiratory system are the lungs, which function to take in oxygen and expel carbon dioxide as we breathe.

The gas exchange process is performed by the lungs and respiratory system. Air, a mix of  oxygen and other gases, is inhaled.

In the throat, the trachea, or windpipe, filters the air. The trachea branches into two bronchi, tubes that lead to the lungs.

Once in the lungs, oxygen is moved into the bloodstream. Blood carries the oxygen through the body to where it is needed.

Red blood cells collect carbon dioxide from the body’s cells and transports it back to the lungs.

An exchange of oxygen and carbon dioxide takes place in the alveoli, small structures within the lungs. The carbon dioxide, a waste gas, is exhaled and the cycle begins again with the next breath.

The diaphragm is a dome-shaped muscle below the lungs that controls breathing. The diaphragm flattens out and pulls forward, drawing air into the lungs for inhalation. During exhalation the diaphragm expands to force air out of the lungs.

Adults normally take 12 to 20 breaths per minute. Strenuous exercise drives the breath rate up to an average of 45 breaths per minute.

Related:

• Respiratory System: Facts, Function and Diseases

The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.

An average adult has 5 to 6 quarts (4.7 to 5.6 liters) of blood, which is made up of plasma, red blood cells, white blood cells and platelets.

The heart is a muscular organ with four chambers. Located just behind and slightly left of the breastbone, it pumps blood through the network of arteries and veins called the cardiovas- cular system.

The systemic circulation is a major portion of the circulatory system. The network of veins, arteries and blood vessels transports oxygenated blood from the heart, delivers oxygen and nutrients to the body's cells and then returns deoxygenated blood back to the heart.

The system of blood vessels in the human body measure about 60,000 miles (96,560 kilometers).

Arteries carry oxygen-rich blood from the heart through the body. Veins carry oxygen-poor blood back to the heart.

The superior vena cava carries oxygen-poor blood into the heart. The aorta carries oxygenated blood from the heart to organs and tissues.

Related:

• Circulatory System: Facts, Function & Diseases

The new virus that causes Middle East respiratory syndrome (MERS) has been compared to that of severe acute respiratory syndrome (SARS) — the viruses belong to the same family, and are particularly deadly to infected people — however, the two conditions have some important differences, a new study says.

While MERS appears to be more deadly in those it infects, it also seems to be less contagious than SARS, the researchers said.

The evidence so far also suggests it's unlikely that MERS will follow a similar path to SARS, the researchers said.

Both MERS and SARS belong to a family of viruses called coronaviruses. SARS was first reported in Asia in 2002, and in less than a year, infected more than 8,000 people around the world, about 10 percent of whom died. MERS first appeared in Saudi Arabia in September last year, and has since infected 90 people and caused 45 deaths.

The new study is the largest to date on MERS, examining information from 47 people with the condition. [6 Superbugs to Watch Out For]

The majority of infections have been in Saudi Arabia, although some infected people lived in or traveled to Jordan, Qatar and the United Arab Emirates. Among people admitted to the hospital with MERS, the most common symptoms were fever (98 percent), chills (87 percent), cough (83 percent) and shortness of breath (72 percent). Some patients also reported gastrointestinal symptoms, including diarrhea and vomiting.

Unlike SARS, which tended to affect younger and healthier people, MERS appears to mainly infect people with underlying chronic conditions. Ninety-six percent of people with MERS in the study had a chronic condition such as diabetes, high blood pressure, heart disease or kidney disease.

In those it does infect, MERS progresses rapidly, leading to death a week earlier, on average, compared with SARS, the researchers said. Sixty percent of people with chronic illnesses who contracted MERS died, compared with just 1 percent of people with chronic illnesses who contracted SARS.

The high death rate seen with MERS (50 percent) may be because researchers are, so far, only picking up the very severe cases of illness. Many more people may have caught MERS, but do not show symptoms, the researchers said.

The researchers said rapid and accurate tests to diagnose the disease are urgently needed. And more studies are needed to determine the scope of the outbreak, as well as risk factors for infection, and factors that might predict which patients are most likely to die from the infection, the researchers said.

The study is published today (July 26) in the journal Lancet Infectious Diseases.

Follow Rachael Rettner @RachaelRettner. FollowLiveScience @livescience, Facebook & Google+. Original article on LiveScience.com .

Air pollution sets off nearly as many heart attacks as physical exertion, alcohol or coffee, a new review has found.

Air pollution accounts for 4.8 percent of heart attacks, while coffee and alcohol each accounts for 5 percent and physical exertion accounts for 6.2 percent, based on an analysis of data from 36 studies worldwide.

The results show that air pollution can harm not only the lungs, but the heart , said Dr. Andrea Baccarelli, an associate professor of public health at Harvard School of Public Health in Boston, who wrote an editorial accompanying the study online today (Feb. 23) in the journal Lancet.

"It is just a moderate risk factor, but because everyone is exposed to air pollution, it becomes very important on the community level," Baccarelli told MyHealthNewsDaily.

Heavy particles, inflammation and clotting are all hazards to the heart presented by air pollution, he said.

Common risks

Belgian researchers examined 36 studies conducted in various countries between January 1960 and January 2010 to examine the percentage of heart attacks attributable to common risk factors.

They took into account how much the general population is exposed to each risk factor. For example, cocaine use increases a person's heart attack risk by 23 times, but because so few people use the drug, it accounts for only 0.9 percent of heart attacks, according to the review.

They found that air pollution increased a person's heart attack risk by 5 percent. But because all the people in the studies were exposed to air pollution, its role in the risk for the general population is higher than some other factors, Baccarelli said.

The analysis also showed that drinking coffee increases a person's heart attack risk by 1.5 times, and drinking alcohol increases risk by three times, but more people are exposed to air pollution than drink coffee or alcohol.

Time spent in traffic or on the road accounted for 7.4 percent of heart attacks in the review, whereas negative emotions accounted for 3.9 percent and anger accounted for 3.1 percent, researchers said.

Heavy meals accounted for 2.7 percent, positive emotions accounted for 2.4 percent and sexual activity accounted for 2.2 percent of heart attacks, according to the review.

Adverse effects of air pollution

It's no surprise that air pollution has adverse effects on the heart, Baccarelli said. There are a number of ways heavy particles in the air, which come largely from traffic, and other pollutants can wind up affecting our bodies, he said.

Heavy particles from pollution can enter the lungs and bloodstream, allowing them to travel to the heart and increase heart disease risk, Baccarelli said.

Air pollutants also promote inflammation in the lungs, which can lead to inflammation of the heart and other parts of the body and can prompt a heart attack, he said. Inflammation of the lungs can also raise the risk of blood clots, which can damage the coronary arteries.

Pass it on: Air pollution accounts for about the same number of heart attacks as physical exertion, alcohol and coffee.

• Beyond Vegetables and Exercise: 5 Ways to be Heart Healthy
• Heart Disease Can Be a Serious, Silent Problem in Young Women
• 10 Medical Myths That Just Wonâ??t Go Away

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChan.