Free-Tailed Bats May Be Behind Ebola Epidemic

The idea that wild animals such as bats and gorillas could be the culprits of the Ebola epidemic sweeping across West Africa is nothing new. But now a new study suggests that insectivorous free-tailed bats, which weren't previously implicated in the outbreak, may be behind the deadly disease.

The findings were published in the journal EMBO Molecular Medicine.

A hollow, bat-filled tree in the small village of Meliandou in Guinea was a popular playing spot for children, including 2-year-old Emile Ouamouno, who may have contracted Ebola from this playground, according to the study. This young boy (who died in December 2013) was the index case, or the first person known to have become infected. Since then, the Ebola virus has spread from Meliandou into other areas of Guinea and Sierra Leone, Liberia, Nigeria and Senegal, and claimed the lives of 7,800 people.

"People have said, 'How can you be sure that the boy played in the tree?'" Fabian Leendertz, a veterinarian at the Robert Koch Institute in Germany who specializes in zoonotic diseases, told Live Science. "But how likely is it that a kid would not play in a playground next to his house? We talked a lot to the other children, and found out that they are actually quite big bat hunters."

Ebola virus disease epidemics are of zoonotic origin, meaning they're transmitted to human populations either through contact with larger wildlife or by direct contact with bats. But careful monitoring has ruled out large mammals as a source of infection, with no evidence of a concurrent outbreak seen among these wildlife populations.

Fruit bats, on the other hand, are commonly suspected as sources of the illness because bat meat is a popular delicacy in certain African cultures, therefore exposure to these small flying mammals via hunting and meat consumption is common in the area. However, if food-borne transmission from fruit bats were to blame, that would mean adults would have had to become infected before or at the same time as the index case.

But this latest study offers a new explanation and expands the range of possible Ebola sources to a new, less considered type of bat. Researchers looking for the origins of the largest Ebola outbreak ever recorded in history found that free-tailed bats (Mops condylurus) lived in the aforementioned tree, making the species a likely reservoir of the disease, the researchers say.

The team conducted a four-week field study in Guinea in April 2014 to examine human exposure to bats, to survey local wildlife and to capture and sample bats in Meliandou and in neighboring forests.

Researchers cannot say for sure that Emile got Ebola from one of the bats living in the tree, Leendertz told Live Science - the tree somehow burned down and killed the thousands of bats that called it home. Plus the dead bats were either already removed from the scene or eaten by locals, not giving researchers a chance to test the carcasses for the Ebola virus. But the study does for the first time implicate free-tailed bats in the Ebola epidemic that's been puzzling scientists for months.

The Ebola outbreak is known to be running rampant in West Africa, but the virus even managed to reach the United States starting back in late September, with four confirmed cases to date, one of them fatal. According to the US Centers for Disease Control and Prevention (CDC), symptoms of Ebola may appear anywhere from two to 21 days after exposure, including fever, severe headache, muscle pain and weakness, diarrhea and vomiting.

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