The Ebola virus can spread through contact with an infected person's blood, feces and vomit, but some information online suggests it's also possible to get Ebola by being near an infected person who sneezes.
Experts say it's extremely unlikely that Ebola could spread through a sneeze. And in fact, this has never happened.
"People don't need to be concerned about catching Ebola from a sneeze," said Dr. Amesh Adalja, a senior associate at the University of Pittsburgh Medical Center for health security. "You have to remember that Ebola is not a respiratory disease. It does not cause people to sneeze."
Indeed, sneezing does not appear anywhere among the symptoms of Ebola listed in the newest study of people with the disease in Sierra Leone, which was published Wednesday (Oct. 29) in the New England Journal of Medicine. Out of 44 people in the study who were infected with the virus, the most prevalent symptoms were fever and headache. Just 21 percent, or 6 people, with fatal cases and one person with a nonfatal case had symptoms that included coughing. [2014 Ebola Outbreak: Full Coverage of the Viral Epidemic]
Moreover, coughing develops later in the course of the disease. Infected people would likely already be in a hospital and have severe symptoms, such as vomiting and diarrhea, by the time they began coughing, Adalja told Live Science.
How Ebola works
Ebola doesn't make people sick right away. Once the virus enters the body, it begins a so-called incubation period, which can range from two to 21 days.
During this period, Ebola is not found in the bloodstream to a measurable degree. Instead, the virus stays deep in the body, in the spleen, for instance. This is why infected people are not symptomatic, nor are they contagious, during the incubation period.
"When the virus starts to escape from the spleen into the bloodstream is when you start to see symptoms occur," Adalja said.
As the virus multiples and invades more organs, such as the liver and intestinal tract, people become sicker. "By that time, you should already be so ill that you're in the hospital and being cared for by people who are wearing the personal protective equipment for infection control," said Dr. William Schaffner, an infectious disease specialist at the Vanderbilt Medical Center in Nashville.
In addition to bodily fluids, such as blood, vomit and diarrhea, health care workers need be careful of sweat, Schaffner said.
"Late in the infection — and I emphasize late in the infection — direct contact with their skin or their sweat is also hazardous, but not when they first develop a fever," he said.
There is no known case of Ebola being transmitted by sneezing, both Schaffner and Adalja said.
Such a transmission would take an extraordinary series of coincidences: A person would have be standing, without proper protective equipment, within 3 feet (1 meter) of an infected person who was "in a later stage of illness, when the virus is disseminated throughout the body," Adalja said. "And because Ebola doesn't cause people to sneeze, somebody would probably have to provoke a sneeze."
Then, the material from that sneeze would still have to enter one of the person's mucus membranes, he said.
Airborne vs. droplets
Unlike the bacteria that cause tuberculosis or the virus that caused smallpox, the Ebola virus is not airborne. With airborne viruses, "Infectious particles can remain in the air," Adalja said. "Even after a person leaves the room, the air is still considered infectious."
Any droplets of fluid that could contain Ebola can travel only about 3 feet before they fall to the ground, because of gravity, he said.
In West Africa, where the Ebola outbreak started earlier this year, thousands of people have contracted Ebola through exposure to bodily fluids. The people getting sick are often those caring for patients who have diarrhea, vomiting and bleeding, but the caregivers do so without wearing any personal protective equipment, Adalja said. "That's what you need to worry about, because that's how this disease is spreading."
"Sneezing is just not something that is part of the constellation of symptoms with Ebola," he said.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Laura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU.