Studies Show Airborne Transmission of Ebola Rare in Pigs, Unlikely in Humans

While doctors and researchers have been busy studying what has caused the most recent outbreak of the Ebola virus and how to stop it, one thing most agree on is that the risk of airborne infection is minimal at best.

A story in The Science News offers a useful roundup of recent studies on Ebola transmission pathways, including several quotes from infectious disease experts pointing out that the most common form of transmission of the virus is when uninfected people come in direct contact with the bodily fluids of infected people. This is especially true in cases of health care workers not taking proper precautions with infected patients and people living in high-risk areas coming in direct contact with blood, saliva, diarrhea, and other fluids from infected people. The story cited a previous study that showed the virus could potentially be spread through the air from pigs to monkeys, but also showed that is very unlikely to happen with humans.

“If it’s going to spread by aerosols, then pigs are the species to do it,” noted Derek Gatherer, a viral evolutional biologist at Lancaster University in England.

The study cited also showed that while pigs can be carriers of the virus there has been no evidence that they contributed to the current health crisis in West Africa.

In a story on vox.com, Hana Weingartl of the Canadian Food Inspection Agency was quoted as saying the airborne threat from pigs is not enough to raise red flags for people.

“You cannot take the pigs and think that it will go the same way in humans,” she said. “One has to consider the species. For pigs, the [Ebola] infection ends up as an infection of the lungs — they have high amounts of the virus in the respiratory tract and so they cough it out. Or when they sneeze or squeal it just gets out of the lungs. So the virus is in the air directly.”

The lead author of the paper on pig transmission also did a follow up study looking at the possibility of human transmission and reported the unlikelihood of such an event. The website scienceblogs.com cited the study as saying in part, “airborne transmission in natural outbreaks cannot be a common occurrence and is possibly insignificant by the account of several reports.”

As of August 8, the US Centers for Disease Control and Prevention was reporting 1779 suspected and confirmed cases of the virus contributing to 961 suspected deaths in Guinea, Sierra Leone, Liberia, and Nigeria.