How Common Are HIV and AIDS?

The first case of AIDS was reported in 1981, but the disease may have existed unrecognized for many years before that. HIV infection leading to AIDS has been a major cause of illness and death among children, teens, and young adults worldwide. AIDS has been the sixth leading cause of death in the United States among 15- to 24-year-olds since 1991.

In recent years, AIDS infection rates have been increasing rapidly among teens and young adults. Half of all new HIV infections in the United States occur in people who are under 25 years old; thousands of teens acquire new HIV infections each year. Most new HIV cases in younger people are transmitted through unprotected sex; one third of these cases are from injection drug usage via the sharing of dirty, blood-contaminated needles.

Among children, most cases of AIDS — and almost all new HIV infections — resulted from transmission of the HIV virus from the mother to her child during pregnancy, birth, or through breastfeeding.

Fortunately, medicines currently given to HIV-positive pregnant women have reduced mother-to-child HIV transmission tremendously in the United States. These drugs (discussed in detail in the Drug Treatments section of this article) are also used to slow or reduce some of the effects of the disease in people who are already infected. Unfortunately, these medicines have not been readily available worldwide, particularly in the poorer nations hardest hit by the epidemic. Providing access to these life-saving treatments has become an issue of global importance.