Tuberculosis and human immunodeficiency virus infection during the 1990's.

Among the many infectious complications of infection with human immunodeficiency virus (HIV), tuberculosis is now recognized as one of the most important. Coexisting HIV infection is believed responsible for the soaring incidence of tuberculosis in Africa, and for the increase in the number of reported cases in the United States. As HIV-induced immunosuppression worsens, tuberculosis may supervene by reactivation of remotely acquired infection or failure to defend against newly acquired Mycobacterium tuberculosis. Both mechanisms undoubtedly occur in Africa where the rate of exposure is high; the former prevails in the United States. The risk of tuberculous infection progressing to tuberculous disease is about six times higher in HIV seropositive than seronegative persons. Although not incontrovertibly established, tuberculosis probably also has a deleterious effect on coexisting HIV infection, either by accelerating the rate of destruction of CD4+ lymphocytes and/or promoting the release of new virions from HIV-infected macrophages. Tuberculosis, whether HIV-linked or not, can be controlled by the traditional means of case-finding and treatment, vaccination with BCG, and chemoprophylaxis. HIV infection can be controlled by eliminating high-risk behavior, and using uncontaminated blood and other medical supplies. An extensive campaign is needed to prevent further spread of these dual scourges that are overwhelming already meager health resources in many parts of the world.