By December 1997, 641,086 cases of AIDS in adults and children had been reported to the CDC; and >390,000 were reported to have died, including >80% of those diagnosed before 1990. In 1996, for the first time in the epidemic, the number of persons diagnosed with an AIDS opportunistic infection as well as the number of deaths among persons with AIDS declined. The recently available antiretroviral treatments as well as the success of a variety of preventive interventions are credited with these declines. The rates of reported AIDS cases vary substantially by age, gender, race-ethnicity, and geographic region, emphasizing that the epidemic in the United States (as well as in the world) is not one epidemic but the product of “hundreds of epidemics” of varying intensity.

Among AIDS cases reported in 1997, 35% of those in adults were homosexual or bisexual men and 24% were IDUs. Heterosexual contact was responsible for 7% of cases among men and 38% of cases among women; it is estimated that heterosexual sex has now surpassed injecting drug use as the major risk factor for HIV infection among women.

However, sex with an IDU was identified as the risk factor in 27% of cases of heterosexually acquired AIDS in 1997 and, thus, the heterosexual epidemic in the United States remains closely linked to drug use. Less than 1% of AIDS cases notified in 1997 have hemophilia or other coagulation disorders; 1% of cases were associated with transfusion of blood, blood components, or tissue transplantation. Most transfusion-associated AIDS cases in the United States received the infected blood prior to 1985, when HIV antibody screening of all blood and plasma donations was instituted; however, 37 adults and 2 children have developed AIDS after receiving blood that was screened negative for HIV antibodies, and 13 adults have developed AIDS after receiving tissue, organs, or artificial insemination from HIV-infected donors. Four of the 13 received these from a donor who was negative for HIV antibodies at the time of donation. The proportion of AIDS cases initially reported without risk information has increased in recent years, especially among women. However, after investigation, most of these cases are reclassified within the usual risk categories.

By December 1997, a total of 8086 cases of AIDS had been reported in children younger than age 13 years, with 58% reported to have died. Most pediatric AIDS cases are the result of perinatal transmission of HIV infection. However, as a consequence of implementation in 1994 of the results of the ACTG 076 trial-the U.S./France multicenter study that proved that zidovudine given to the HIV-infected mother could reduce by 66% the risk that the infant also will become infected-there has been a dramatic reduction in the number of perinatally acquired HIV/AIDS cases. In the United States, the number of infants under 1 year of age diagnosed with AIDS decreased from 905 cases in 1992 to 516 cases in 1996.

AIDS has disproportionately affected black and Hispanic minority populations in the United States. In 1997, 45% of reported adult/adolescent cases (40% of reported cases among men and 61% among women) and 62% of pediatric cases were black. That same year, 21% of adult/adolescent and 23% of pediatric cases were among Hispanics. In contrast, blacks and Hispanics are estimated to account for 11% and 9% of the U.S. population, respectively.

In 1997, AIDS rates were approximately 20 and 7 times higher for black and Hispanic women than for white women. The rates for black and Hispanic men were 7 and 3 times higher than for white men. Racial disparities in pediatric AIDS rates reflect those in women (Table 409-3) . HIV infection and AIDS cases continue to increase more rapidly in those racial-ethnic minority populations, particularly in association with injecting drug use and heterosexual transmission.

Because AIDS related deaths have declined markedly, the prevalence of HIV/AIDS has actually increased in the United States. The CDC estimates that approximately 250,000 people are living with AIDS, of which 40% are white, non-Hispanic; 38% are black; and 20% are Hispanic.

HIV infection has had a large impact on mortality in young adults in the United States. By 1992, HIV infection had become the leading cause of death in men in the 25- to 44-year-old age group and the fourth leading cause of death in women in that age group in the United States. The number of deaths due to HIV/AIDS peaked in the United States in 1995 with 50,700-three quarters of which was in the 25- to 44-year-old age group. In 1996, the number of AIDS-related deaths declined 23% to 39,200; however, this decline has been more marked among whites (33%) than among blacks or Hispanics (13% and 20%, respectively). AIDS is now the second leading cause of death among people between the ages of 25 and 44 years, following unintentional injuries.