Prospects for preventing cryptococcosis in persons infected with human immunodeficiency virus.
Cryptococcosis is a major cause of illness and death among persons infected with human immunodeficiency virus (HIV). Its management must include both initial and maintenance treatment. Although most authorities favor an initial period of therapy with amphotericin B for acute cryptococcosis, the triazoles play a role in both the management of acute disease and subsequent maintenance therapy. AIDS surveillance data collected by the Centers for Disease Control and Prevention document the occurrence of cryptococcosis in more than 17,000 (6.2%) of adults with AIDS in the United States, although this figure is known to be an underestimate. The risk of cryptococcosis among HIV-infected persons is highest at CD4+ lymphocyte counts of < 100/microL. Although cryptococcosis is especially frequent among AIDS patients who are black, male, or injection drug users, the explanations for these patterns remain unclear. Whether geographic differences in rates of cryptococcosis result from variations in the environmental distribution of Cryptococcus neoformans as well as in the distribution of HIV infection is also unclear. Although exposure to pigeon feces is the best known of the putative exposure-related risk factors, proof is lacking that avian excreta are the primary environmental source of the organism in most cases of cryptococcosis. Prophylaxis with triazoles can prevent cryptococcosis and may be considered for adults and adolescents with CD4+ counts of < 50/microL. However, it is uncertain whether prophylaxis will affect survival, be cost-effective, or have an adverse impact on the susceptibility of a variety of fungi to antifungal drugs. Vaccines and monoclonal antibodies designed to prevent or modify cryptococcosis in HIV-infected persons are in the experimental stage.