HIV prevention among drug users: an international perspective from Thailand.

All too often in reviews of HIV prevention needs, the role of drugs is summarily dismissed, especially in contexts where the heterosexual epidemic is the primary mode of transmission. Substance use and abuse, particularly injection drug use, play a paramount role in maintaining the heterosexual spread of HIV, as well as in maintaining epidemics where heterosexual spread of the infection has come under control due to prolonged and concerted HIV prevention activities. This article presents several themes to place in the developing country context what we have learned about substance use-related HIV prevention and the special problems of HIV interventions. First, the article briefly examines the international production and trade routes of opium and heroin and their role in the HIV epidemic, as well as the importance of substance abuse in heterosexual epidemics. Second, it presents a case study of HIV control that has been internationally acclaimed as one of the few successes in achieving a meaningful reduction in heterosexually transmitted HIV--Thailand. The Thai response to the injection drug use HIV epidemic, however, has been muted, and its impact on future epidemic dynamics is evaluated. The article concludes with a discussion of existing research gaps concerning the role of drug use in HIV epidemics in the developing world, with Thailand as an example.