Nontuberculous mycobacterial disease in rhesus monkeys

In a colony of rhesus monkeys (Macaca mulatta), 42 cases of nontuberculous mycobacterial-related disease were identified from 1970 to 1978. The disease affected young and old colony-born and wild-caught monkeys of both sexes. Serotypes 1, 2, 4, 8, and 18 of the Mycobacterium avium-intracellulare group were isolated from different monkeys. The lesions were primarily intestinal in 36 monkeys. Lesions of the large intestine, small intestine, and mesenteric lymph nodes were characterized by diffuse accumulations of large macrophages containing many acid-fast bacteria. Acid-fast bacteria could not be identified histologically in four monkeys with typical histories of diarrhea and weight loss, positive skin reactions to the tuberculin test with M. avium tuberculin, and isolation of the organism from tissues on one or more occasions. Two monkeys had histologically positive lesions limited to the lungs, although chronic colitis of undetermined cause was present.