Leprosy is now being observed in wild chimpanzees for the first time. The outbreak in two different areas of West Africa puzzles researchers and veterinarians. So far leprosy has been confined mostly to humans. It does not appear humans are spreading the disease to chimps, leading experts to question what they know about the disfiguring illness.
It is treatable by antibiotics but treating wild chimpanzees raises a host of practical, medical and ethical questions.
The affected chimps live more than 1,000 miles apart. One group is in Cantanhez National Park in Guinea-Bissau, the other is in Tai National Park in Ivory Coast. The national park is the research site of the Tai Chimpanzee Project. Known to scientists as Hansen’s Disease, leprosy is caused by a slow growing bacteria Mycobacterium leprae . Early treatment is effective but delayed treatment can lead to nerve damage and disfigurement. In humans it requires very close and prolonged contact to spread. Contact between researchers and chimpanzees does not appear to meet the transmission standards so experts are re-thinking what they know.
The chimpanzees with leprosy are western chimpanzees, one of four separate types of chimpanzees. There are an estimated 50,000 western chimpanzees out of a total of 300,000. Western chimpanzees are different from other chimpanzees. They use wooden spears, make cave homes, share food and forage at night. They are considered endangered.
Leprosy has appeared in other mammals, including 9 banded armadillos and red suirrels. But the genotype of the bacteria in he cases was the same as mostly found in humans, That suggests a leap from human to animals. But the chimps had traces of the bacteria with rare genotypes. Genotypes not normally found in human sufferers. This suggests the disease is lurking elsewhere in the chimp’s environment. Possibly in animals they eat or in the environment itself
Recently we reported on chimpanzees in Gabon that may be using medicinal insects to treat small wounds on themselves and each other.