FIGURE 1.2. Annual percentage of new AIDS cases per mode of exposure, 1981 to 1993. NOTE: MSM = men who have sex with men; MSM & IDU = men have sex with men and inject drugs; IDU = injection drug use; HETERO = heterosexual contact. SOURCE: Unpublished data from the Centers for Disease Control and Prevention, National Center for Infectious Diseases, 1994.

(54 percent). Figure 1.3 illustrates that this ethnic/racial disparity also was observed in new pediatric cases (55 percent were African American). A closer examination of cases by exposure category reveals that 71 percent of the newly reported cases among African American women were related to injection drug use; 52 percent of African American women diagnosed with AIDS in 1993 injected drugs, and an additional 19 percent of those cases were attributed to ''sex with injecting drug user" (i.e., heterosexual contact). That same year, for other racial/ethnic categories of women diagnosed with AIDS linked with injection drug use, the corresponding proportions were 61 percent of white women (44 percent injected drugs and 17 percent reported sexual contact with an injection drug user) and 76 percent of Hispanic women (48 percent injected drugs and 28 percent reported sexual contact with an injection drug user). Among both male and female injection drug users, this ethnic disparity is greatest in the northeastern United States.

In sum, these epidemiologic data indicate that injection drug users are currently a major component of the HIV epidemic in the United States and a key bridge to the heterosexual populations. They underscore the critical importance of directing prevention efforts to injection drug users and their sexual partners.