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Insect-eating bats, not fruit bats, sparked Ebola outbreak, study says

Researchers say the current Ebola epidemic probably began with children playing with insect-eating bats

The fruit bat has long been suspected of sparking the ongoing Ebola epidemic in West Africa, but new research suggests that it may have been an insect-eating bat that first transmitted the virus to a human host.

In a study published Tuesday in the journal EMBO Molecular Medicine, researchers said that the suspected natural reservoir for the Ebola virus may include more species of bats than previously thought.

After conducting interviews and testing animals in Meliandou, Guinea -- the village in Guéckédou prefecture where a 2-year-old boy first contracted the virus -- researchers said the outbreak probably started when the boy and other children were playing with insect-eating bats in a large, hollow tree stump.

"Villagers reported that children used to play frequently in this hollow tree," wrote wildlife epidemiologist and senior study author Fabian Leendertz, of Germany's Robert Koch-Institute in Berlin, and his colleagues.

"When we arrived, the tree had been mostly burned and only the stump and fallen branches remained. Villagers reported that it burned on March 24, 2014 and that once the tree caught fire, a 'rain of bats' started.... The bats were described as lolibelo, that is, small, smelly bats with a long tail."

It has not been proven that bats are the animal reservoir for the Ebola virus, but lab tests have shown that bats can be infected without dying, and are therefore believed to harbor the virus.

Chimpanzees and antelopes can also become infected in the wild, but are more likely to die, according to researchers.

To date, the Ebola outbreak has sickened more than 20,129 people and killed more than 7,879, according to the World Health Organization. The nations that have suffered the most illnesses are Guinea, Sierra Leone and Liberia.

Scientists had hypothesized that infected fruit bats had spread the virus to humans, because they are hunted for food.

However, Leendertz and his colleagues said that while Meliandou villagers have hunted fruit bats, none of the initial cases of Ebola appeared to have been linked to fruit bat bushmeat.

Instead, residents of the 31-house village -- which sits amid open farmland -- implicated insectivorous free-tailed bats.

"Insectivorous bats were reported to be commonly found under the roofs of houses and similar [hinding places] ... these bats are reportedly targeted by children, who regularly hunt and grill them over small fires," the authors wrote.

While conducting their research, study authors captured bats and tested them for the virus, and also studied other animals in the area, including chimpanzees and antelope.

In previous Ebola outbreaks, susceptible mammals like chimps and antelopes have suffered population declines. However the number of large mammals around Meliandou appears to have grown, not decreased. This suggests that they were not the source of infection, researchers wrote. 

"Our findings support the idea that bats were the source of the current ... epidemic in West Africa and enlarge the list of plausible reservoirs to include insectivorous bats," they wrote.

"Future sampling campaigns, in-depth serological studies, and modeling efforts should take into account the possibility that fruit bats may not always be the ultimate source of Ebola virus disease outbreaks."

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