More than 5,000 gorillas may have died in recent outbreaks of the Ebola virus in central Africa, a study says.
Scientists fear Ebola and hunting combined could wipe out gorillas
Scientists warn that, coupled with the commercial hunting of gorillas, it may be enough to push them to extinction.
The study, published in the US journal Science, looked at gorilla colonies in Republic of Congo and Gabon. Ebola is also blamed for many chimpanzee deaths.
One of the most virulent viruses known, Ebola has killed more than 1,000 people since it was first recorded in 1976.
Ebola causes viral haemorrhagic fever - massive internal and external bleeding - which can kill up to 90% of those infected.
Scientists are still working on a vaccine and there is no known cure.
The latest study, carried out by an international team, has confirmed previous concerns about how badly the virus is affecting gorillas.
"Add commercial hunting to the mix, and we have a recipe for rapid ecological extinction," the report says.
One of the most virulent viral diseases
Damages blood vessels and can cause extensive bleeding, diarrhoea and shock
Killed more than 240 people in the Democratic Republic of Congo in 1995
Transmitted by infected body fluids
Kills up to 90% of victims, depending on the strain
There is no cure
"Ape species that were abundant and widely distributed a decade ago are rapidly being reduced to remnant populations."
The researchers, led by Magdalena Bermejo of the University of Barcelona, focused on western gorillas, one of two gorilla species. The other is the eastern gorilla.
In 2002 and 2003, several outbreaks of Ebola flared up in human populations in Gabon and Congo.
The researchers found a "massive die-off" in gorillas in Congo's Lossi Sanctuary between 2002 and 2004.
"The Lossi outbreak killed about as many gorillas as survive in the entire eastern gorilla species," the study says.
The researchers concluded that the apes were not only infected by other species, such as fruit bats, but were also transmitting the virus among themselves.
Ebola was passing from group to group of the endangered animals, they found, and appeared to be spreading faster than in humans.
Outbreaks of the disease in humans have sometimes been traced to the bushmeat trade.
According to World Health Organization figures, Ebola killed 1,200 people between the first recorded human outbreak in 1976 and 2004.