A trip to the beach can be the perfect way to pass a summer's day. But as you search for a spot to place your towel, you should know you're not just sharing the sand with fellow beach lovers — you're sharing it with some pretty creepy critters, too. Although most microbes in the sand are harmless, some are linked with disease. Here are five types of pathogens found in sand.
Walking barefoot on a tropical beach may sound idyllic, but in some areas, you'll want to be wary of hookworms, which are parasites that can infect both people and animals. Some species of hookworm that typically infect cats and dogs can be transmitted to people through sand or contaminated soil, according to the Centers for Disease Control and Prevention (CDC).
This happens when infected animals defecate in sand or soil and pass hookworm eggs in their stool. People can then become infected if they walk barefoot or lie down on the infested sand or soil, the CDC says. Indeed, a Canadian couple recently revealed that they contracted hookworms in their feet while walking barefoot on a Caribbean beach. (These hookworms are typically found in tropical or subtropical regions.)
The hookworm larvae can burrow into unprotected skin and then crawl around in the top layers of skin. However, because humans aren't the normal hosts for these hookworms, the parasites usually don't live more than six weeks in people, the CDC says.
The superbug MRSA is particularly problematic in hospitals, but the bacteria can also be found out in the environment, including on beaches, studies have found.
MRSA, which stands for methicillin-resistant Staphylococcus aureus, is a type of staph bacteria that can cause skin infections and is resistant to several antibiotics. Some people can carry staph bacteria or even MRSA on their skin or in their noses without showing symptoms. (In the United States, about one-third of the population carries staph and 2 percent carries MRSA without showing symptoms.) But in other cases, such as when a person gets a cut or wound in their skin, the bacteria causes an infection.
A number of studies have found staph bacteria and MRSA in seawater and in sand. For example, a 2012 study in the journal Water Research analyzed water and sand samples from three Southern California beaches, finding staph bacteria in 53 percent of beach sand samples and MRSA bacteria in 2.7 percent of sand samples.
It's unclear whether that amount of staph and MRSA bacteria in sand poses a health risk to beachgoers, and researchers have called for more studies to look into this question. But in the meantime, showering after a stint on the beach or in the ocean should help provide protection against staph and MRSA infection, the researchers of the 2012 study said.
You might have heard that swimming in ocean water could get you sick with a stomach bug. Indeed, health officials monitor water quality at beaches and close these beaches when bacteria levels are too high, in order to prevent illness. But what about bacteria in the sand?
Beach sand can also harbor a number of bacteria that can cause gastroenteritis, or stomach infections that lead to diarrhea, nausea and vomiting. A 2012 study in the journal Applied and Environmental Microbiology, which analyzed sand from 53 California beaches, found Escherichia coli and Enterococcus — bacteria typically found in human intestines — as well as Salmonella and Campylobacter, which are sometimes causes of food poisoning.
But could these bacteria in sand really make you sick? Maybe — a 2009 study that surveyed more than 27,000 Americans who visited the beach found that people who reported digging in the sand or being buried in the sand were more likely to develop gastrointestinal illness shortly after their beach trip than those who didn't report these activities. However, the researchers noted that their study couldn't prove that bacteria in sand caused the people's gastrointestinal illnesses.
The fungus is among us at the beach, too. Types of fungi that cause skin and nail infections — which belong to a broad group known as "dermatophytes" — have been found on beaches. They may spread through direct contact with people, animals or sand, according to the American Society for Microbiology (ASM).
Other types of fungi found at beaches include species of Aspergillus, which may cause lung infections, and Candida, which can cause yeast infections. However, infections with Aspergillus andCandida are more common among people with weakened immune systems, ASM said.
At beaches that allow dogs, the sand might harbor Toxocara canis, a parasitic roundworm that typically infects canines, according to ASM. People can become infected with T. canis by accidentally swallowing soil that has been contaminated with dog feces that contain T. canis eggs, according to the CDC.
Still, the risk of catching this parasite from beach sand is unclear. However, a study in France conducted in the 1990s found T. canis to be a common parasite on beaches, and another study, this one in Australia, found no T. canis eggs in more than 250 samples from beaches and parks that allowed dogs.
Because this parasite is more commonly found in puppies than in older dogs, the Australian study concluded that the major risk of T. canis to humans is from environments where puppies are found.
Original article on Live Science.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.