A mysterious epidemic may be responsible for the disappearance of over half the chimpanzees at a colony in southeast Guinea, one of Africa's most important research sites for the primates, officials said Saturday.
Pepe Soropogui, head of the chimpanzee investigation at the Bossou Environmental Research Institute (IREB), said no more than 12 West African chimpanzees remain from a population of around 30 in 2002.
Primate experts are baffled by the dwindling population at Bossou, close to Mount Nimba in the border region with Ivory Coast and Liberia.
"There are theories that some chimpanzees have contracted a sort of bronchitis or pneumonia probably transmitted by man, but we are not sure because chimpanzees have funeral rites and take away the bodies after death," said Marie Claude Gauthier of the Jane Goodall Institute for wildlife research and conservation.
Chimpanzees share around 98 percent of man's genetic makeup and are sensitive to human diseases, she said.
Other theories include the migration of the chimps through the thick jungles towards Liberia or the Ivory Coast. "Nothing has been ruled out. It is a mystery," Gauthier said.
Chimpanzees have already disappeared from four countries in West Africa, leaving Guinea and Ivory Coast with the most important populations. According to the latest census, there are more than 8,000 chimpanzees in Guinea.
The population at Bossou is one of the oldest permanent colonies identified by researchers in the wild. Its chimps are known for using stone hammers to crack open palm oil nuts -- among the most sophisticated use of tools seen in nature.
The encroachment of nearby villages has threatened their habitat and food supplies as well as introducing disease.
"This situation is worrying and we are trying to find the cause of the deaths and disappearances. We still don't have the results of the tests," said Christine Sagno, national head of the water and forestry department.
"In the face of this threat, we have transported to the park in upper Niger, at Faranah, a sanctuary where we are going to welcome 45 chimpanzees in captivity," said Sagno.