Efficacy of a Brief Behavioral Intervention to Promote Condom Use Among Female Sex Workers in Tijuana and Ciudad Juarez, Mexico Thomas L. Patterson, PhD, Brent Mausbach, PhD, Remedios Lozada, MD, Hugo Staines-Orozco, MD, Shirley J. Semple, PhD, Miguel Fraga-Vallejo, MD, Prisci Orozovich, MPH, Daniela Abramovitz, MA, Adela de la Torre, PhD, Hortensia Amaro, PhD, Gustavo Martinez, MD, Carlos Magis-Rodrı ´guez, MD, and Steffanie A. Strathdee, PhD Although commercial sex is quasi legal in the zonas rojas (red light districts) of most Mexi- can cities, HIV prevalence among female sex workers has been low in most parts of the country. 1 For example, among female sex workers in Mexico City and at the Mexico– Guatemala border, HIV prevalence was 0.6% in 1997 2 and in 1998. 3 More recently, reports suggest that HIV prevalence is rising among female sex workers on the Mexico–US border. In a sample of 415 female sex workers in Tijuana in1991, HIV prevalence was 0.5%, 4 but in our more recent study of 924 female sex workers in Tijuana (bordering San Diego, CA) and Ciudad Juarez (bordering El Paso, TX), HIV prevalence was 6.0%. 5 In the same study, prevalences of gonorrhea, chlamydia, and syphilis titers consistent with active infection were 6.4%, 13.0%, and 14.2%, respectively. In Mexican culture, sex with female sex workers is tolerated as a display of virility and machismo at all socioeconomic levels. 6–8 The sexually permissive environment in Mexican border cities also attracts large numbers of ‘‘sex tourists’’ from the United States and other countries who are attracted by newspaper ad- vertisements and Web sites advertising prosti- tution. 9 More than two thirds of female sex workers in Tijuana and Ciudad Juarez report having US clients, and these women have a higher prevalence of sexually transmitted in- fections (STIs) and higher levels of transmission risk behaviors, including sex without a condom and injection use of drugs. 10 Mexican law requires female sex workers to obtain a permit if they wish to work without prosecution in Tijuana’s zona roja, but more than half work without permits. In Ciudad Juarez, permits are not required. In both cities, female sex workers operate out of multiple venues including cantinas, bars, nightclubs, motels, and street corners. Seventy percent of these female sex workers were born in other Mexican states or Central America, 11 and most entered prostitution out of economic necessity. Extreme poverty may compromise their ability to turn down offers of higher payments for unprotected sex. 12,13 In border regions, where sex work is toler- ated and HIV prevalence is rising, there is a clear need to ensure that condoms are consis- tently used during commercial sex transactions to prevent outbreaks of HIV or STIs in both countries. We developed a brief behavioral intervention to enhance condom use negotia- tion among Mexican female sex workers. 11 Here, we report its first results and examine its efficacy in Tijuana and Ciudad Juarez. METHODS Settings Tijuana, Mexico’s largest city on its border with the United States, is home to an estimated 1410700 persons. Tijuana and its US neigh- bor, San Diego, California, form the world’s largest binational metropolis. Roughly half of Baja California’s population lives in Tijuana, although over half of the city’s inhabitants were born outside the state. 14 In 1999, the per capita gross regional product in Tijuana was $6800, less than one quarter of that for San Diego. 15 The border crossing between Tijuana and San Diego is the busiest in the world. In 2005, border officials tallied over 45 million north- bound crossings from Tijuana to San Diego County, 16 and 42 000 persons who live in Tijuana head north to San Diego every day. 17 Baja California ranks second among Mexico’s 32 states in terms of cumulative AIDS inci- dence. 18 Estimates of the number of female sex workers in Tijuana vary, but the most widely cited figure is 9000. 15 Ciudad Juarez, the largest city in the state of Chihuahua, has a population of 1313338. 14 In 2000, 36% of Ciudad Juarez’s inhabitants had Objectives. We examined the efficacy of a brief behavioral intervention to promote condom use among female sex workers in Tijuana and Ciudad Juarez, Mexico. Methods. We randomized 924 female sex workers 18 years or older without known HIV infection living in Tijuana and Ciudad Juarez who had recently had unprotected sex with clients to a 30-minute behavioral intervention or a didactic control condition. At baseline and 6 months, women underwent interviews and testing for HIV, syphilis, gonorrhea, and chlamydia. Results. We observed a 40% decline in cumulative sexually transmitted illness incidence (P = .049) in the intervention group. Incidence density for the interven- tion versus control groups was 13.8 versus 24.92 per 100 person-years for sexually transmitted illnesses combined (P = .034) and 0 versus 2.01 per 100 person-years for HIV (P < .001). There were concomitant increases in the number and percentage of protected sex acts and decreases in the number of unpro- tected sex acts with clients (P < .05). Conclusions. This brief behavioral intervention shows promise in reducing HIV and sexually transmitted illness risk behaviors among female sex workers and may be transferable to other resource-constrained settings. (Am J Public Health. 2008;98:2051–2057. doi:10.2105/AJPH.2007.130096) RESEARCH AND PRACTICE November 2008, Vol 98, No. 11 | American Journal of Public Health Patterson et al. | Peer Reviewed | Research and Practice | 2051