SPONTANEOUS LEPROSY IN A WILD-CAUGHT CYNOMOLGUS MACAQUE

Naturally occurring Mycobacterium leprae has been previously documente d in only two species of nonhuman primates from West Africa-the chimpa nzee and the sooty mangabey. We report here the first known case of sp ontaneous leprosy in an Asian macaque. A wild-caught cynomolgus macaqu e imported from The Philippines developed a reaction to a tuberculin s kin test after 3 years at the California Regional Primate Research Cen ter (CRPRC), University of California-Davis, Davis, California, U.S.A. Biopsies of concurrent skin lesions suggested a cutaneous mycobacteri al infection. Diagnosis of the infection was obtained by a polymerase chain reaction (PCR) assay specific for M. leprae. Clinical presentati on, histopathological findings, and ELISA serology for M. leprae-speci fic PGL-I and to the LAM mycobacterial antigens were consistent with t hose of human borderline (BB) leprosy. Longitudinal serologic data sug gest that the cynomolgus macaque had subclinical leprosy at the time o f arrival in the CRPRC quarantine. Intradermal tuberculin testing is t he traditional method for screening nonhuman primate populations for m ycobacterial infections. Exposure to nontuberculous mycobacteria, such as M. leprae, may sensitize some individual primates to nonspecific m ycobacterial antigens, resulting in false-positive tuberculin reaction s. Susceptibility of the cynomolgus macaque and other nonhuman primate s to M. leprae should be re-evaluated. Cynomolgus macaques and, possib ly, other nonhuman primates may serve as valuable experimental models of leprosy in humans.