Naturally acquired and experimental leprosy in nonhuman primates.

Naturally-acquired leprosy has been observed in chimpanzees and sooty mangabey monkeys. Experimental multibacillary leprosy was established in 24 of 36 mangabey monkeys, 7 of 34 rhesus monkeys, and 15 of 19 African green monkeys following intravenous and intradermal inoculation of Mycobacterium leprae. The experimental disease strongly resembles leprosy in humans clinically, histopathologically, and immunologically. Thus, in addition to nine-banded armadillos in Louisiana and Texas, chimpanzees and sooty mangabeys in Africa, in the wild or in captivity, may serve as a zoonotic source of M. leprae. Investigators using chimpanzees and monkeys should be alerted to the possibility of naturally-acquired leprosy.

Experimental lepromatous leprosy in the white-handed gibbon (Hylobatus lar): successful inoculation with leprosy bacilli of human origin.

Leprosy bacilli of human origin were inoculated into a white-handed gibbon by the i.v. and i.p. routes, and also locally into ears, testis and around an ulnar nerve. The animal was observed closely during a period of nearly 15 years and did not exhibit any clinical evidence of cutaneous or neurological disease. At death, a wide range of tissues was taken for bacterial counts and histological examination, and a disseminated and progressive infection was demonstrated. Acid-fast bacilli were found in many sites; their morphological appearance distribution in nerves, and pattern of multiplication in mouse foot-pads, and also the presence of anti-mycobacterial antibody in the serum and the absence of specific lymphocyte transformation were all in keeping with an infection by Mycobacterium leprae, at an early lepromatous stage. This is probably the first fully documented report of experimental lepromatous infection in a primate. The findings are discussed in relation to the long incubation period of le promatous leprosy and the difficulties of diagnosing the disease at an early stage in man.