Distribution of Sexually Transmitted Diseases and Risk Factors by Work Locations Among Female Sex Workers in Tijuana, Mexico

Background: Sex work is regulated in the Zona Roja (red light district) in Tijuana, Mexico, where HIV and sexually transmitted disease (STD) prevalence is high among female sex workers (FSWs). We examined the spatial distribution of STDs by work venue among FSWs in Tijuana. Methods: FSWs aged 18 years and older who reported unprotected sex with >= 1 client in the past 2 months underwent testing for HIV, syphilis, gonorrhea, and Chlamydia. HIV/STDs were mapped by venue (i.e., bar, hotel) and Getis-Ord Gi statistics were used to identify geographic hotspots. High-risk venues were then identified using a standardized STD ratio (high risk defined as a ratio >= 1.25). Logistic regression was used to assess correlates of working at a high risk venue. Results: Of 474 FSWs, 176 (36.4%) had at least 1 bacterial sexually transmitted infection (STI); 36 (7.6%) were HIV-positive. Within the Zona Roja, 1 venue was identified as a geographic "hotspot," with a higher than expected number of HIV/STD-positive FSW (P < 0.05) as compared to neighboring venues. Using the STD ratio definition, 11 venues were identified as high-risk; FSWs working in these locations had higher education, were more likely to report always using drugs with sex, and having mostly US clients. They were less likely to be registered FSWs or to live at their work venue. Conclusions: A relatively few number of sex work venues accounted for a large proportion of the HIV/STI burden among FSWs in Tijuana. Structural interventions that focus on sex work venues could help increase STI diagnosis, prevention, and treatment among FSWs in Tijuana.