Where did Ebola come from, and who discovered it?

Ebola is thought to come from animals, most likely fruit bats, which are believed to carry the virus without being made ill by it. Scientists first described it in 1976, after two outbreaks that began months apart: southern Sudan in June and Zaire, now the Democratic Republic of the Congo, in August. The virus took its name from the Ebola River, near where the Zaire outbreak happened.

The natural reservoir, the animal in which the virus lives between outbreaks, has yet to be confirmed, but bats are considered the most likely candidate. In experiments on 24 plant and 19 vertebrate species, only bats became infected, and they showed no signs of disease. How the virus first passes from an animal to a person is not entirely clear, but it is believed to involve direct contact with an infected wild animal or fruit bat. Areas undergoing deforestation are among the most likely places for outbreaks, because changes to the landscape bring wildlife into closer contact with humans.

The Zaire outbreak began in the village of Yambuku. A school headmaster, Mabalo Lokela, fell ill after a trip that included a visit to the Ebola River. He was first believed to have malaria and was given quinine. In all, 318 cases and 280 deaths, an 88 percent fatality rate, occurred in Zaire. Peter Piot concluded that Belgian nuns had inadvertently started the epidemic by giving unnecessary vitamin injections to pregnant women without sterilising the syringes and needles.

The virus itself was identified from a blood sample taken from a sick nun. Peter Piot, at the Institute of Tropical Medicine in Antwerp, was part of the team that observed it, and he has received most of the credit. But the Congolese doctor Jean-Jacques Muyembe took that sample, helped lead the first response, and is himself described as one of the discoverers.