Leprosy in a chimpanzee. Postmortem lesions.

A young (5-7 year old) male chimpanzee died 33 months after the first clinical manifestations of a naturally acquired disease that was similar to disseminated leprosy in man. At autopsy there were diffuse or multifocal histiocytic infiltrations of the skin, nasal mucosa, pharynx, lung interstitium, liver, spleen, sclera, testicles, adrenal glands, and peripheral lymph nodes. Major nerves of the forearms had extensive fibrosis. There were large numbers of acid-fast bacilli (AFB), many occurring as globi, in histiocytes in most affected tissues including nerves. The histopathologic features of the disease and the microbiologic and antigenic properties of the AFB in the tissues indicate that Mycobacterium leprae or an organism indistinguishable from it was the causative agent. This and other cases of leprosy in nonhuman primates indicate that studies of the development of nonhuman primate models for leprosy may be worthwhile.