The epidemiology of the acquired immunodeficiency syndrome in the 1990s.

Since the recognition of AIDS in 1981, it has become a global pandemic afflicting more than 6 million people worldwide. To date, more than 22 million people are infected with HIV-1, the cause of AIDS, and more than 40 million people may be infected with HIV by the year 2000. In the United States, AIDS has become the leading cause of death in young men and the fourth leading cause of death in young women. HIV is primarily transmitted sexually, parenterally, and perinatally, with increasing evidence of heterosexual transmission in the United States and worldwide. Factors associated with transmission and susceptibility to HIV are discussed, and the natural history of HIV and means of intervention are detailed in this article.