The Global HIV/AIDS Pandemic

In 1999, an estimated 34.3 million people worldwide were living with HIV or AIDS. Since the beginning of the pandemic, AIDS has resulted in more than 18.8 million deaths, including 2.8 million during 1999 alone. More than 95 percent of all HIV-infected people live in the developing world, and approximately 70 percent of all HIV-infected people live in sub-Saharan Africa (UNAIDS, 2000).

The AIDS epidemic is having devastating effects on the social and economic welfare and health of developing nations. The resulting instability, in addition to the public health implications of increased travel and migration, has direct implications for the United States. The Committee suggests these issues be addressed in a future study focused on optimizing the U.S. role in fighting the global pandemic.

progression and extend the lives of people with AIDS, and in part to the success of earlier HIV prevention efforts (CDC, 1999b). Since mid-1998, however, the number of AIDS cases and deaths diagnosed each quarter has remained relatively stable (CDC, 2000d). The Centers for Disease Control and Prevention (CDC) suggests that the stabilization is likely due to a combination of several factors including: treatment failure and the fact that some people have problems adhering to treatment regimens; the fact that HIV prevention efforts have already reached many of those individuals who are most disposed to treatment; and the fact that many people cannot be reached with early testing and treatment (CDC, 2000d).

Between 1993 and 1999, the estimated number of people living with AIDS increased by 69 percent (CDC, 2000b) (Figure A.1). Today, the number of people reported to be living with AIDS4 (299,944) is at an all-time high (CDC, 2000b).

Modes of Transmission

In the United States, the primary modes of HIV transmission have been sexual intercourse and injection drug use. Of the 724,656 AIDS cases reported among adults and adolescents since the beginning of the epidemic, 47 percent have been linked to sex between men, 25 percent to injection drug use, 10 percent to heterosexual intercourse, 6 percent to men who have sex with men and inject drugs, and 2 percent to contaminated blood or blood products (CDC, 2000b). In recent years, however, disease patterns have begun to shift. A declining proportion of new AIDS cases now is being attributed to sex between men, and an increasing proportion of cases is being linked to heterosexual exposure. However, MSM remains the single largest exposure group (CDC, 2000b). The pro-

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