Characteristics of female sex workers with US clients in two Mexico-US border cities.

BACKGROUND HIV prevalence is increasing among female sex workers (FSWs) in Tijuana and Ciudad Juarez, 2 Mexican cities on the US border. Quasilegal prostitution in both cities attracts large numbers of sex tourists. We compared FSWs with and without US clients in both cities. METHODS FSWs aged > or =18 years reporting unprotected sex with > or =1 client within the last 2 months, who were not knowingly HIV-infected, were enrolled in a behavioral intervention study. At baseline, participants underwent interviews, antibody testing for HIV and syphilis, and vaginal swabs for detecting gonorrhea and Chlamydia. Logistic regression identified factors associated with reporting >1 US client. RESULTS Of 924 FSWs, 69% had US clients. Median age and duration in sex work were 32 and 4 years. Prevalence of HIV, infectious syphilis (titer > or =1:8), gonorrhea, Chlamydia, and any STI was 6%, 14%, 6%, 13%, and 27%, respectively. Compared with other FSWs, FSWs with US clients were more likely to have syphilis titers > or =1:8 (16% vs. 10%, P = 0.01), gonorrhea (8% vs. 2%, P <0.001) or any STI, including HIV (30% vs. 20%, P = 0.002). Factors independently associated with having US clients were: living in Tijuana, being younger, speaking English, being paid more for having sex without a condom, having >250 clients in the last 6 months, having syphilis titers > or =1:8, and injecting drugs. CONCLUSIONS In these border cities, FSWs reporting US clients were more likely to have current STIs and to engage in higher-risk behaviors. Intensified binational prevention efforts involving both FSWs and their clients are urgently needed.