Source of Ebola Outbreak in West Africa Might Be Bats, Study Says

The toddler in Guinea who is thought to have been the first case in the current outbreak of Ebola in West Africa may have caught the virus from bats in a hollow tree near his village, scientists said Tuesday.

A study, led by scientists from the Robert Koch Institute in Berlin and published online by the journal EMBO Molecular Medicine, could not prove the link because the tree in Meliandou, a village of 31 houses in the Guéckédou district, burned in late March and the bats inside were immolated or flew off.

The fire took place shortly after Guineans were warned that the virus might come from bats. By then, at least 10 local people were dead.

However, the scientists found enough residual DNA in the charred trunk and fecal DNA in nearby soil to identify the animals as Mops condylurus, long-tailed insect-eating bats that were previously suspected in an outbreak of the Sudan strain of Ebola virus, which is related to the Zaire strain that has infected over 20,000 West Africans.

 The study is important because scientists have wondered how a boy named Emile Ouamouno, who died in December 2013 and whom various reports describe as 1 or 2 years old, could have been the index patient.

Most human outbreaks have started in adults: hunters or charcoal-burners finding sick apes or forest antelopes and butchering them for food, for example, or miners working in bat-filled caves. In one case, an outbreak is thought to have come from bats roosting in a cotton mill.

But there was no large number of deaths among chimpanzees or other animals in the Meliandou area, the scientists said.

Large fruit bats have been suspected because they are hunted for meat in Guinea, where a peppery bat soup was popular before the outbreak.

Some scientists think that humans can contract Ebola by picking up fruit that fruit bats have contaminated with saliva or feces.

But there are no fruit bat colonies near Meliandou, the study said. Local men who hunted them during the migratory season had to walk long distances. Also, none of the initial cases in the village involved bat hunters.

The scientists captured several bat species near the village, but none had the virus or the antibodies to it.

Villagers said that children, including Emile, often caught and played with bats in the tree, which was about 50 yards from Emile’s house and near a path women used to fetch water.

The work was done by a team that included an anthropologist to investigate human interaction with animals, 10 ecologists to survey local wildlife and four veterinarians who netted bats, taking blood and tissue samples.

Normally, the bats are released unharmed, but Fabian Leendertz, the lead author, told the magazine Scientific American that his team had killed them. Otherwise, he said, local people would have said, “Look at those white people releasing bad bats.”

Rumors that whites and people from the capital cities had started the epidemic led to confrontations and the murders of several health care workers.