In much of the world,
pneumocystosis remains the most common life-threatening
opportunistic infection among patients with HIV disease. The
infection is caused by Pneumocystis carinii--an organism whose identity as a fungus or parasite is still debated. What is no longer debated, after a decade of
AIDS, is that
pneumocystosis is almost entirely preventable and eminently treatable. Understanding has improved concerning when prophylaxis should be initiated. It is also recognized that, at least with the agents available today, antiretroviral
therapy alone will not prevent
pneumocystosis. Sputum induction and the use of
monoclonal antibodies have modestly improved our ability to diagnose the
infection; however, invasive procedures are still required for most patients, and unusual presentations of the disease, such as cavitary lesions, apical infiltrates, pneumothoraces, and extrapulmonary
infection, are not infrequently seen. For treatment,
trimethoprim-sulfamethoxazole and intravenous
pentamidine remain the mainstays; oral
therapy with
dapsone and
trimethoprim can be as effective as conventional
therapy in mild disease, permitting treatment on an outpatient basis. Adjunctive
steroids are useful for treatment of moderate to severe
pneumocystosis, but clinicians should be alert to the possibility of activation of other
latent infections during and after courses of
steroids. Both
aerosol pentamidine and
trimethoprim-sulfamethoxazole are effective prophylaxis. The latter appears to be more effective and costs much less, but the results of comparative trials are not yet available. More data are also needed on the safety, efficacy, and relative advantages of
dapsone for prophylaxis. The first decade of the
AIDS epidemic has been a decade of progress against
pneumocystosis. In the next decade, the emergence of new technologies for diagnosis and of new agents for prophylaxis and treatment will bring us closer to the goal of controlling this serious
infection.