A decade has passed since our first report of naturally acquired leprosy in the nine-banded armadillo. Our studies and those of others during this period confirm the identification of the etiologic agent as Mycobacterium leprae. Confirmation is based on the results of histopathologic examination and microbiologic evaluations that included attempts to culture the organism, flourescent antibody studies, mycolic acid analysis, and DNA determinations demonstrating complete relatedness between the natural agent and M. leprae. Surveys involving large numbers of animals demonstrate a significant prevalence of the disease in armadillos captured in Louisiana and Texas. The discovery of naturally acquired leprosy in a chimpanzee in 1977 and a sooty mangabey monkey in 1979 reinforce the concept of leprosy as a zoonosis. Extensive contact with armadillos has been implicated by other observers in seven patients with leprosy in Texas. We believe the prevalence of leprosy in wild armadillos requires that they be considered a source of infection in patients from geographic areas where leprosy and armadillos co-exist.
Eight of twenty armadillos (
Dasypus novemcinctus
L.) developed severe lepromatous leprosy 3 to 3.5 years after inoculation with viable
Mycobacterium leprae
. A total of 988 grams of lepromas containing an estimated 15 to 20 grams of leprosy bacilli has been harvested from these animals. The large amounts of material now available will permit in-depth studies of the biochemistry and metabolism of the leprosy bacillus, and the animal model should make possible definitive studies on the immunology, chemotherapy, and epidemiology of the disease.
Eleven mangabey monkeys inoculated with Mycobacterium leprae developed lepromatous-type leprosy. Nine of the mangabeys were inoculated with M. leprae isolated from a mangabey with naturally acquired lepromatous leprosy. Immune function was depressed in some of these animals after dissemination of the disease. Two mangabeys developed lepromatous leprosy after inoculation with human M. leprae passaged in an armadillo. Three rhesus and three African green monkeys inoculated with mangabey-derived M. leprae also developed lepromatous leprosy. Mangabeys may be the first reported nonhuman primate model for the study of leprosy. Rhesus and African green monkeys may also prove to be reproducibly susceptible to the disease.
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