Researchers working in Gabon and Congo have identified three species of fruit bat as the long-sought reservoirs of one of the deadliest known human pathogens, the Ebola virus.
The team tested more than 1,000 bats and other animals before tracing the virus to fruit bats, which are commonly eaten by people in Central Africa, according to a report in today's issue of the journal Nature.
Researchers found minute genetic traces of the virus in 22.6% of the bats tested. More important, they found that the virus produces no symptoms in infected bats, thus allowing it to spread without disabling its carrier, said lead researcher Eric Leroy, an immunologist with the International Center for Medical Research in Gabon.
Dr. Sanford Kuvin, head of tropical infectious diseases at Israel's Hebrew University, said the study provided strong evidence of Ebola's presence in bats and should prompt people in the region to "avoid contact with the creatures at all costs."
Ebola hemorrhagic fever first came to light in 1976, erupting simultaneously in 55 villages near the headwaters of the Ebola River in the Democratic Republic of Congo, then known as Zaire. About 90% of those infected died.
According to the U.S. Centers for Disease Control and Prevention, there have been 17 outbreaks since then. There is no cure for the disease.
The virus is also fatal to some animals. After a 2003 outbreak in Gabon and Congo, chimpanzee numbers in one region dropped 89% and western lowland gorilla numbers fell by half.
The virus first causes fever, then heavy internal and external bleeding, which starts from under the skin, proceeds to the mouth, ears and eyes and then affects the internal organs, leading to death through either shock or organ failure.
Because of its lethality, the virus has been considered a potential bio-weapon threat.
Where the virus hides in nature has been a mystery that has "had smart people scratching their heads ever since 1976," said Dr. Anne Anglim, an assistant professor of infectious disease at USC's Keck School of Medicine.
The disease has had a baffling ability to emerge and then disappear from researchers' view.
Leroy's research showed that the fruit bats harbored the virus at levels so low they escaped many conventional DNA tests.
Ending the tradition of catching bats for food could significantly reduce the risk of human Ebola infections, he said.