Researchers have confirmed cases of the disease among two unconnected West African populations of chimpanzees, in Guinea-Bissau and the Ivory Coast.

Analysis published in the journal Nature shows the strains of leprosy are different, and both are uncommon among humans.

The origins of the infections are unclear, but the research team – led by the University of Exeter and the Robert Koch Institute – say the findings show leprosy is probably circulating in more wild animals than was previously suspected, either as a result of exposure to humans or other unknown environmental sources.