London, Dec 30: A young boy playing near a colony of virus-infected bats may have precipitated the outbreak of Ebola in West Africa, scientists said Tuesday.
The two-year-old boy - described as the index case, or "patient zero" - became infected and was the first to die in the village of Meliandou in Guinea, the Daily Mail reported.
Before his death, he had been near a tree harbouring free-tailed bats, according to reports.
Subsequently, the Ebola virus spread to other areas of Guinea, Sierra Leone, Liberia, Nigeria and Senegal.
The epidemic represents the largest ever-recorded Ebola outbreak, killing 7,800 people by Dec 17, 2014.
Fruit bats are the commonly suspected carriers of the Ebola virus and have been linked to previous outbreaks in Africa.
They are often hunted for food, but according to scientists, food-borne transmission would have affected adults before or at the same time as the two-year-old boy.
This suggested a source of infection unrelated to food and that the boy somehow came into contact with the insect-eating free-tailed bats.
Researchers from the Robert Koch-Institute in Berlin were part of a team, which took part in a four-week field mission in Guinea.
This was to examine human exposure to bats, survey the local wildlife and capture and sample bats in Meliandou and in neighbouring forests.
However, the village where the boy died was not located in the forest. Instead, the source of the infection was probably a large colony of free-tailed insectivorous bats occupying a hollow tree, scientists concluded.
Villagers reported that children often used to play in and around the tree, which might have resulted in a massive exposure to the bats.
According to researcher Fabian Leendertz, the Ebola virus is transmitted to humans either through contact with larger wildlife or by direct contact with bats.
Writing in the journal EMBO Molecular Medicine he said: "We monitored large mammal populations close to the index village Meliandou in south-eastern Guinea and found no evidence of a concurrent outbreak."
Instead, a more plausible source of the outbreak was contact with bats, rather than larger wildlife.
The Ebola disease is a severe, often fatal illness in humans. It is transmitted to people from wild animals and spreads in humans through direct contact with the bodily fluids of an infected person.
Symptoms of the disease typically start between two days and three weeks after contracting the virus.
In the beginning, the symptoms may range from fever, sore throat, muscle pain, and headache.
Then, vomiting and diarrhoea usually follow, along with decreased functioning of the liver and kidneys. Some of those affected may also bleed both internally and externally.