Leprosy and AIDS: a review of the literature and speculations on the impact of CD4+ lymphocyte depletion on immunity to Mycobacterium leprae.

The potent effects of HIV infection on the human immune system, the complexity of the host-parasite interaction in leprosy, and the paucity of current information on the natural history of co-infected patients makes this area a fertile ground for clinical and immunologic investigation. Several studies have now validated the prediction that there exists a large cohort of patients, particularly in Africa, who are concurrently infected with HIV and M. leprae. Sparse but tantalizing evidence suggests that infection with HIV may increase the incidence of leprosy among individuals with subclinical infection with M. leprae, either through shortening the incubation period or by increasing disease penetrance. Similarly, active mycobacterial disease may accelerate the course of HIV disease, as has been postulated to occur during concurrent infections with certain other viral and bacterial pathogens in HIV-positive patients. A subtle and complex interplay between HIV and leprosy may thus result which will impact the observed epidemiology of both illnesses in regions where both are prevalent. Possible effects of the HIV epidemic on leprosy control programs have been outlined by the World Health Organization and in an editorial by Turk and Rees. The published experience provides few guidelines for the clinical care of co-infected patients. The initial response to conventional therapeutic regimens appears to be excellent, but no follow-up data have been included. The possible absence of ENL in these patients would simplify care for multibacillary disease, if this observation is confirmed in larger field studies.(ABSTRACT TRUNCATED AT 250 WORDS)