Leprosy seen in wild chimpanzees for the first time

By Hannah Ryan, CNN

Leprosy has been identified in wild chimpanzees for the first time, according to a new study, in findings that have stunned experts.

The leprosy cases in chimpanzees were found in Guinea-Bissau and the Ivory Coast, making this the first time leprosy has been found in any nonhuman species in Africa, researchers said in a study published Wednesday.

Leprosy is an infectious disease that can seriously damage nerves, skin and the respiratory tract in humans. It can lead to the development of lesions and nodules, as well as the loss of sensation in the limbs and blindness.

Scientists used camera traps to study the behavior of chimpanzees between 2015 and 2019. When looking through the images, the researchers found two males and two females with “severe leprosy-like lesions,” according to the study. Symptoms — similar to those humans experience — progressed over time.

“When I first saw the images of a chimpanzee with nodules and lesions on its face, it struck me right away that this was leprosy because it looked so much like leprosy does in humans,” Kimberley Hockings, a senior lecturer in conservation science at the University of Exeter in the United Kingdom and one of the study’s authors, told CNN Thursday.

It is so far not known exactly how the chimps became infected, but it is thought that it came about either as a result of exposure to humans or “other unknown environmental sources,” the study said.

Leprosy has been seen in wild animals before, such as in red squirrels in the UK and armadillos in the Americas, but it was quite shocking to see leprosy “suddenly turn up in chimpanzees because they are so well-researched,” Hockings noted.

She said that there would now be further research into how the wild chimps came into contact with the disease and what it means for a species that is already at risk due to factors such as hunting and habitat loss.

Hockings added that the discovery was concerning for conservation efforts and researchers.

As for treatment for leprosy in wild chimpanzees, that could prove challenging.

“Treating leprosy in humans is relatively straightforward, especially if it’s diagnosed early enough,” Hockings said.

“But for animals that aren’t habituated to humans, such as these particular populations, it’s very difficult to administer antibiotics. There are constraints to treating animals for leprosy and we have to consider the ethical implications of darting chimpanzees, so that makes the question of treatment a complicated one.”

Hockings said she would be incorporating the discovery into her broader research, which centers around human and great ape interactions, as humans have traditionally been considered the main host for leprosy — and now it’s appearing suddenly in wild chimpanzees.

The research was published in the journal Nature.

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