Samples taken from carcasses, bones, and carrion-eating flies in the Ivory Coast’s Tai National Park (TNP) from 1989 to 2014, revealed that anthrax had caused 38 percent of animal deaths — including 31 out of 55 dead chimps tested.
Other casualties included monkeys, duikers, mongooses and a porcupine.
“Our simulations… suggest that anthrax-induced mortality will result in deterministic population declines and possible extirpation of TNP chimpanzees over the next 150 years,” a team wrote in the journal Nature.
Chimpanzees are particularly vulnerable due to their slow reproduction rate, said the team.
The researchers could not determine where and how the animals were being infected with a type of anthrax first identified in the TNP in 2004.
And they cautioned that infections in apes “are often indicators of disease that can also affect humans.”
Dubbed Bacillus cereus biovar anthracis, the bacteria has also caused chimpanzee, gorilla and elephant deaths in Cameroon and the Central African Republic, the team said. No human cases have been reported.
Outbreaks of anthrax were previously thought to be more common in arid ecosystems, such as the African savannah where it kills game, cattle, and sometimes humans.
Humans generally acquire the disease from infected animals or from exposure to contaminated animal products. It can be contracted via the skin, the mouth, or through inhalation.
In its commonest form, according to the World Health Organization it causes black sores on the skin, from where it derives its name. Anthrax is Greek for coal.
The bacteria is not transmitted from person to person. Though potentially deadly, it reacts well to treatment with antibiotics.
Anthrax is also a favourite agent in germ warfare, having first been used as a weapon in World War I. More recently, dried bacterial spores were mailed to targets in the United States.
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