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The largest outbreak of the deadly disease Ebola(埃博拉) was caused by an infected bat biting a toddler, say a group of international researchers.

The 17-strong team of European and African tropical disease researchers, ecologists and anthropologists have spent three weeks investigating the outbreak of the disease in Guinea, Liberia, Ivory Coast and Nigeria. The researchers captured the bats and other creatures near the village of Meliandoua in remote eastern Guinea, where the disease began in December 2013. The boy was bitten and passed the infection on to his mother and both died within a week. The disease was then spread far and wide by the people who came to the funeral.

Most of the previous outbreaks have been caused by meat from dead infected animals collected by hunters who then sell it on. Fruit bats, however, are widely eaten in rural West Africa.

The team, led by epidemiologist(流行病学家) Herr Leendertz, a disease ecologist at the Robert Koch Institute in Berlin, are expected to publish their results in a major journal soon.

Herr Leendertz’s team believe that an infected straw-colored fruit bat brought the disease to Guinea. The mammals are known to travel long distances and usually settle in forests near cities. Herr Leendertz said, “ The evidence is not 100 percent and we can only say that it is possible. They can travel far in one night. I don't think an individual bat or colony(群体) migrated all the way from Congo or Gabon to West Africa. These big colonies are connected. There is a possibility for the virus to mix between colonies. The bats share the same fruit. It is likely not to have even been one species of bat. The virus may jump from one species to another."

If the bat theory is confirmed, the locals would try to destroy the colonies, which, Herr Leendertz says, would be an ecological disaster, because bats pollinate(传授花粉) plants and kill insects. And bat hunts would also only increase human contact with potentially infected animals.