Wild chimpanzees in Western Africa have been found with leprosy for the first time ever — and now scientists are struggling to get to the root of the infectious disease that’s mostly found in humans.
The baffling discovery was made in several chimps at Cantanhez National Park in Guinea-Bissau, and in another more than a thousand miles away at Taï National Park in Ivory Coast, according to a new report by Science Magazine.
“I have NEVER seen this in chimps,” wildlife veterinarian Fabian Leendertz, who has a research site at the Ivory Coast park, told the publication.
The ancient disease, now known as Hansen’s disease and caused by the bacteria Mycobacterium leprae, infected as many as 12 million people around the world in the mid-1980s before scientists learned it could be cured with antibiotics.
Leprosy has been found in other animals before — nine-banded armadillos in the Americas and red squirrels in the United Kingdom, the magazine said. Both species carry the same bacterial genotype, called 3I — which has also been found in outbreaks dating back to Medieval Europe — and in both cases, it appears the disease jumped from humans to animals.
But research of leprosy-infected chimps has so far shaped up differently. Two rare genotypes — 2F and 4N/O — have turned up in other chimps found with traces of M. leprae.
The illness in chimps suggests that the leprosy-causing bacterium is lurking elsewhere — either living on the animal the chimps hunt or even in the environment, the magazine said.
Leendertz ruled out human transmission because the disease spreads only from prolonged and close contact and there’ve been no known cases of leprosy among researchers. The genotypes also found in sickened chimps is rare in humans, according to researchers.
“The most likely scenario is that there is some unidentified leprosy reservoir,” Leendertz said.
Anne Stone, an evolutionary geneticist at Arizona State University, Tempe, believes the bacterium had another host before humans evolved.
“The data increasingly points to the possibility that something else than humans is actually the main host,” Stone told Science Magazine.