Hansen’s Disease and One Health

One Health is the concept that links human health with animal health and the environment. Viable Mycobacterium leprae bacilli have been detected in environmental sources, including in soil and water in countries where Hansen’s disease is endemic. Natural infection of armadillos with M. leprae was first reported in the late 1970s in the USA, where Hansen’s disease is recognized as a zoonosis acquired through direct and indirect contact with wild armadillos. In Brazil, M. leprae infection in wild armadillos was not reported until 2002, with subsequent studies showing that infection is widespread in these animal hosts. Human contact with armadillos through hunting, butchering, cooking, and eating is common in many parts of Brazil, despite laws protecting this endangered animal. Although human-to-human transmission is likely to be the main driver of endemicity, these forms of contact are associated with an increased risk of Hansen’s disease in endemic and non-endemic settings. Zoonotic risk has been neglected by health authorities in Brazil, but the 2021–2030 WHO Global Hansen’s Disease Strategy acknowledges the existence of zoonotic reservoirs.