Seroprevalence of HIV among female sex workers in Bangkok: evidence of ongoing infection risk after the "100% condom program" was implemented.

Background: After implementation in 1991 of a nationwide campaign to promote condom use during commercial sex, HIV-1 seroprevalence among young men began to decrease in 1994. However, it is unknown to what degree female sex workers (FSWs) have been protected from infection. Methods: FSWs attending a government clinic in Bangkok in 1997 and 1998 were interviewed, counseled, and tested for evidence of prior syphilis by Treponema pallidum hemagglutination assay (TPHA) and for HIV-1 antibodies. Results: Among the 500 participants, women who began sex work more recently reported less risky sex behavior when they were first potentially exposed to HIV infection, and TPHA reactivity rates were lower among these women. However, their HIV infection rates were higher. HIV seroprevalence was 5.5% among 91 women who began sex work before 1989, 8.0% among 87 women who began during 1990 to 1993, and 12.5% among 322 women who had begun since 1994. Conclusions: Although condom use is critical to HIV prevention, women in this study who began sex work after the condom promotion campaign was implemented were still at high risk for HIV infection. Additional measures are needed to prevent HIV infection among the many young women who initiate or continue to engage in commercial sex.