Correlates of perceived risk of HIV infection among persons who inject drugs in Tijuana, Baja California, Mexico.

OBJECTIVE: We identified correlates of perceived risk of HIV infection among persons who inject drugs (PWID) in Tijuana. MATERIALS AND METHODS: PWID ≥18 years of age who injected drugs in the past month were recruited between 2006-2007 and completed risk assessment interviews and serologic testing for HIV, syphilis, and tuberculosis. Logistic regression was used to determine factors associated with high-perceived risk of HIV infection. RESULTS: Among 974 PWID, HIV prevalence was 4.4%; 45.0% of participants perceived themselves to be more likely to become HIV infected relative to other PWID in Tijuana. Participants who reported high-perceived risk of HIV infection participated in high-risk behaviors such as injecting with used syringes, transactional sex, and were less likely to have had an HIV test. CONCLUSIONS: Recognition of HIV infection risk was associated with high risk behaviors and markers of vulnerability. Findings support efforts to encourage HIV testing and access to health care for this vulnerable population.

Evaluating outcome-correlated recruitment and geographic recruitment bias in a respondent-driven sample of people who inject drugs in Tijuana, Mexico.

Respondent-driven sampling's (RDS) widespread use and reliance on untested assumptions suggests a need for new exploratory/diagnostic tests. We assessed geographic recruitment bias and outcome-correlated recruitment among 1,048 RDS-recruited people who inject drugs (Tijuana, Mexico). Surveys gathered demographics, drug/sex behaviors, activity locations, and recruiter-recruit pairs. Simulations assessed geographic and network clustering of active syphilis (RPR titers ≥1:8). Gender-specific predicted probabilities were estimated using logistic regression with GEE and robust standard errors. Active syphilis prevalence was 7 % (crude: men = 5.7 % and women = 16.6 %; RDS-adjusted: men = 6.7 % and women = 7.6 %). Syphilis clustered in the Zona Norte, a neighborhood known for drug and sex markets. Network simulations revealed geographic recruitment bias and non-random recruitment by syphilis status. Gender-specific prevalence estimates accounting for clustering were highest among those living/working/injecting/buying drugs in the Zona Norte and directly/indirectly connected to syphilis cases (men: 15.9 %, women: 25.6 %) and lowest among those with neither exposure (men: 3.0 %, women: 6.1 %). Future RDS analyses should assess/account for network and spatial dependencies.

Syringe confiscation as an HIV risk factor: the public health implications of arbitrary policing in Tijuana and Ciudad Juarez, Mexico.

Female sex workers who inject drugs (FSW-IDUs) face elevated risk for HIV/STIs and constitute a key population for public health prevention. Through direct and indirect pathways including human rights violations, policing practices like syringe confiscation can compound FSW-IDU health risk and facilitate the spread of disease. We studied correlates of experiencing syringe confiscation among FSW-IDUs in northern Mexico, where formal policy allows for syringes to be available over the counter without a prescription, but police practices are often at odds with the law. FSW-IDUs reporting recent syringe sharing and unprotected sex with clients in Tijuana and Ciudad Juarez were administered surveys and HIV/STI testing. Logistic regression was used to identify correlates of syringe confiscation. Among 624 respondent FSW-IDUs, prevalence of syringe confiscation in the last 6 months was 48%. The following factors were positively associated with syringe confiscation: testing positive for HIV (adjusted odds ratio [aOR] = 2.54, 95% confidence interval [CI] = 1.11-5.80), reporting sexual abuse by police (aOR = 12.76, 95% CI = 6.58-24.72), engaging in groin injection (aOR = 1.84, 95% CI = 1.15-2.93), injecting in public (aOR = 1.64; 95% CI = 1.14-2.36), and obtaining syringes from pharmacies (aOR = 1.54; 95% CI = 1.06-2.23). Higher education level was negatively associated with syringe confiscation (aOR = 0.92, 95% CI = 0.87-0.98) as was frequent injection with clients within the last month (aOR = 0.64, 95% CI = 0.44-0.94). This analysis adds to the body of evidence linking unauthorized law enforcement actions targeting high-risk groups with HIV and other adverse health outcomes. Using a public health lens to conceptualize abuse as a structural risk factor, we advocate for multi-prong prevention, systematic monitoring, and evidence-based intervention response to deleterious police practices.

Correlates and contexts of US injection drug initiation among undocumented Mexican migrant men who were deported from the United States.

Preventing the onset of injection drug use is important in controlling the spread of HIV and other blood borne infections. Undocumented migrants in the United States face social, economic, and legal stressors that may contribute to substance abuse. Little is known about undocumented migrants' drug abuse trajectories including injection initiation. To examine the correlates and contexts of US injection initiation among undocumented migrants, we administered quantitative surveys (N = 309) and qualitative interviews (N = 23) on migration and drug abuse experiences to deported male injection drug users in Tijuana, Mexico. US injection initiation was independently associated with ever using drugs in Mexico pre-migration, younger age at first US migration, and US incarceration. Participants' qualitative interviews contextualized quantitative findings and demonstrated the significance of social contexts surrounding US injection initiation experiences. HIV prevention programs may prevent/delay US injection initiation by addressing socio-economic and migration-related stressors experienced by undocumented migrants.

Prevalence and correlates of female condom use and interest among injection drug-using female sex workers in two Mexico-US border cities.

Little is known about female condom use among female sex workers who inject drugs (FSW-IDUs) in Northern Mexico, where HIV/STI prevalence is high. We examined the prevalence and correlates of female condom use and interest in female condom use among FSW-IDUs aged >18 years in Tijuana and Ciudad Juárez, Mexico enrolled in a behavioral intervention designed to reduce high-risk sexual and injection behaviors. Of 621 FSW-IDUs, 8 % reported ever using female condoms, and 67.2 % expressed interest in trying female condoms. Factors independently associated with female condom use were having had a client become angry at the suggestion of using condoms and having engaged in unprotected vaginal sex with non-regular clients. Factors independently associated with interest in using female condoms were lifetime physical abuse and lifetime sexual abuse. Increasing the availability of female condoms and providing education on their use in the context of drug use and violence is recommended.

"Injection first": a unique group of injection drug users in Tijuana, Mexico.

Using baseline data from a study of injection drug users (IDUs) in Tijuana, Mexico (N = 1,052), we identified social and behavioral factors associated with injecting at the same age or earlier than other administration routes of illicit drug use (eg, "injection first") and examined whether this IDU subgroup had riskier drug using and sexual behaviors than other IDUs. Twelve-percent "injected first." Characteristics independently associated with a higher odds of "injection first" included being younger at first injection, injecting heroin as their first drug, being alone at the first injection episode, and having a sexual debut at the same age or earlier as when they initiated drug use; family members' illicit drug use was associated with lower odds of injecting first. When adjusting for age at first injection and number of years injecting, "injection first" IDUs had lower odds of ever overdosing, and ever trading sex. On the other hand, they were less likely to have ever been enrolled in drug treatment, and more commonly obtained their syringes from potentially unsafe sources. In conclusion, a sizable proportion of IDUs in Tijuana injected as their first drug using experience, although evidence that this was a riskier subgroup of IDUs was inconclusive.

Mujer Mas Segura (Safer Women): a combination prevention intervention to reduce sexual and injection risks among female sex workers who inject drugs.

BACKGROUND: Female sex workers who inject drugs (FSW-IDUs) are at risk of acquiring HIV, sexually transmitted infections (STI) and blood-borne infections through unprotected sex and sharing injection equipment. We conducted a 2×2 factorial randomized controlled trial to evaluate combination interventions to simultaneously reduce sexual and injection risks among FSW-IDUs in Tijuana and Ciudad Juarez, Mexico. METHODS/DESIGN: FSW-IDUs ≥18 years reporting sharing injection equipment and unprotected sex with clients within the last month were randomized to one of four conditions based on an a priori randomization schedule, blinding interviewer/counselors to assignment. Due to the extreme vulnerability of this population, we did not include a control group that would deny some women access to preventive information. All women received similar information regardless of group allocation; the difference was in the way the information was delivered and the extent to which women had an interactive role. Each condition was a single 60-minute session, including either an interactive or didactic version of an injection risk intervention and sexual risk intervention. Women underwent interviewer-administered surveys and testing for HIV, syphilis, gonorrhea, Chlamydia, and Trichomonas at baseline and quarterly for 12 months. Combined HIV/STI incidence will be the primary outcome. Secondary outcomes are proportionate reductions in sharing of injection equipment and unprotected sex with clients. DISCUSSION: Of 1,132 women, 548 (48.4%) were excluded (88.9% were ineligible; 11.1% refused to participate or did not return); 584 eligible women enrolled (284 in Tijuana; 300 in Ciudad Juarez). All 584 participants completed the baseline interview, provided biological samples and were randomized to one of the four groups. During follow-up, 17 participants (2.9%) were lost to follow-up, of whom 10 (58.8%) had died, leaving 567 participants for analysis. This study appears to be the first intervention to attempt to simultaneously reduce injection and sexual risk behaviors among FSW-IDUs. The factorial design will permit analysis to determine whether the combination of the two interactive interventions and/or its respective components are effective in reducing injection and/or sexual risks, which will have direct, tangible policy implications for Mexico and potentially other resource-poor countries. TRIAL REGISTRATION: NCT00840658.

Correlates of unprotected anal sex among men who have sex with men in Tijuana, Mexico.

BACKGROUND: Although men who have sex with men (MSM) are disproportionately affected by HIV/AIDS in Mexico, data on current risk behaviors in this population are lacking. This study investigated the prevalence and correlates of unprotected anal intercourse (UAI) in a sample of 260 MSM in Tijuana, Mexico. METHODS: In June 2010, men attending a gay pride celebration were invited to complete a sexual risk survey. Men who reported UAI with a male partner in the past year were compared with men who reported only protected anal sex during the same period. RESULTS: Mean age of participants was 29.7; 54% had a high school diploma or less; and 43% were unemployed. In the past year, 55% had been tested for HIV, 21% reported using illicit drugs before or during sex, and 94% had sex only with men. Overall, 50% reported having UAI with another male in the past year. Factors independently associated with UAI in the past year were unemployment (AOR = 1.87), attending adult movie theaters (AOR = 2.21), using illicit drugs before or during sex (AOR = 2.43), and not having a recent HIV test (AOR = 1.85). CONCLUSIONS: Interventions to promote HIV testing and condom use among men who have sex with men may want to consider venue-specific approaches, as well as focus on drug-use issues in the context of unsafe sex.

Reducing harm from HIV/AIDS misconceptions among female sex workers in Tijuana and Ciudad Juarez, Mexico: A cross sectional analysis.

BACKGROUND: HIV prevalence is increasing among female sex workers (FSWs) in Mexico's Northern border region, who experience multiple occupational risks. Improving vulnerable populations' education, empowerment, and access to preventive services are important components of harm reduction strategies. Given the increasing interest in adapting harm reduction principles from drug use to sex work and other public health responses to the HIV epidemic, we used a sex work harm reduction framework to guide our investigation of FSWs' HIV knowledge. METHODS: From 2004-2006, FSWs aged ≥18 years in Tijuana and Ciudad Juarez participated in a behavioral intervention study and completed structured interviews. Measures included HIV knowledge assessment and factors within each domain of our theoretical framework for sex work harms: (1) socio-demographic factors that may lead to sex work, (2) sex work characteristics and behaviors that may lead to harm, and (3) mutually reinforcing harms that lead to sex work and result from it (e.g., drug abuse). Negative binomial regression identified factors independently associated with suboptimal HIV knowledge (i.e., incorrect responses during the HIV knowledge assessment). RESULTS: Among 924 FSWs, the median proportion of incorrect responses was nearly one third (28% incorrect). Examination of item responses revealed misconceptions regarding specific transmission and prevention mechanisms, including prevention of mother to child transmission. Suboptimal HIV knowledge was independently associated with older age, lower education, living in Tijuana (vs. Ciudad Juarez), inconsistent condom use for vaginal sex with male clients, and lacking prior HIV testing. CONCLUSIONS: Our application of a sex work harm reduction framework to the study of FSWs' HIV knowledge is an important first step in enhancing HIV prevention efforts in Northern Mexican border cities. Our findings imply that interventions should identify and discredit local HIV misconceptions to improve knowledge of specific HIV transmission routes and self-protective strategies (e.g., condom negotiation). Interventions will require materials appropriate for women from diverse socio-economic backgrounds and may benefit from innovative harm reduction approaches such as peer education and outreach.

Intraurban mobility and its potential impact on the spread of blood-borne infections among drug injectors in Tijuana, Mexico.

We explored intraurban mobility of Tijuana, Mexico, injection drug users (IDUs). In 2005, 222 IDUs underwent behavioral surveys and infectious disease testing. Participants resided in 58 neighborhoods, but regularly injected in 30. From logistic regression, "mobile" IDUs (injecting ≥3 km from their residence) were more likely to cross the Mexico/U.S. border, share needles, and get arrested for carrying syringes-but less likely to identify hepatitis as an injection risk. Mobile participants lived in neighborhoods with less drug activity, treatment centers, or migrants, but higher marriage and home ownership rates. Mobile IDUs should be targeted for outreach and further investigation. The study's limitations are noted.

Tuberculosis testing among populations with high HIV risk in Tijuana, Baja California, Mexico.

OBJECTIVE: To assess the prevalence of prior tuberculin skin testing (TST) among populations at risk for HIV infection in Tijuana, Mexico, and to identify factors associated with TST. METHODS: Sex workers, injection drug users, noninjecting drug users, and homeless persons > 18 years old were recruited by using targeted sampling for risk assessment interviews and serologic testing for HIV and Mycobacterium tuberculosis infection. Univariate and multivariate logistic regression were used to identify correlates of self-reported TST history. RESULTS: Of 502 participants, 38.0% reported prior TST, which was associated with previous incarceration in the United States of America [odds ratio (OR) = 13.38; 95% confidence interval (CI) = 7.37-24.33] and injection drug use (OR = 1.99; 95% CI = 1.27- 3.11). Positive results on serologic tests for M. tuberculosis infection (57%) and HIV (4.2%) were not associated with a prior TST. CONCLUSIONS: A history of TST was lower in HIV-positive participants even though TST is indicated for persons with HIV in Mexico. Fewer than half the individuals at high risk for HIV in this study had a history of TST; however, TST was fairly common among those individuals with a prior history of incarceration. Increased tuberculosis screening is needed for populations at risk of contracting HIV in Tijuana, particularly those outside of criminal justice settings.

Mexico's northern border conflict: collateral damage to health and human rights of vulnerable groups.

OBJECTIVE: To compare distributions of human rights violations and disease risk; to juxtapose these patterns against demographic and structural environmental variables, and to formulate implications for structural interventions. METHODS: Female sex workers who inject drugs were surveyed in Tijuana and Ciudad Juarez, Mexico. Structured interviews and testing for sexually transmitted infections (STIs) were conducted (October 2008 to October 2009). Frequencies of individual and environmental factors, including police abuse, risk of HIV infection, and protective behaviors, were compared between sites using univariate logistic regression. RESULTS: Of 624 women, almost half reported police syringe confiscation despite syringes being legal; 55.6% reported extortion (past 6 months), with significantly higher proportions in Ciudad Juarez (P < 0.001). Reports of recent solicitation of sexual favors (28.5% in Tijuana, 36.5% in Ciudad Juarez, P = 0.04) and sexual abuse (15.7% in Tijuana, 18.3% in Ciudad Juarez) by police were commonplace. Prevalence of STIs was significantly lower in Tijuana than in Ciudad Juarez (64.2% and 83.4%, P < 0.001), paralleling the lower prevalence of sexual risk behaviors there. Ciudad Juarez respondents reported significantly higher median number of monthly clients (6.8 versus 1.5, P < 0.001) and lower median pay per sex act (US$ 10 versus US$ 20, P < 0.001) (in the past month). Relative to Tijuana, security deployment, especially the army's presence, was perceived to have increased more in Ciudad Juarez in the past year (72.1% versus 59.2%, P = 0.001). CONCLUSIONS: Collateral damage from police practices in the context of Mexico's drug conflict may affect public health in the Northern Border Region. Itinerant officers may facilitate disease spread beyond the region. The urgency for mounting structural interventions is discussed.

Deportation experiences of women who inject drugs in Tijuana, Mexico.

Deportation from the United States for drug offenses is common, yet the consequences of deportation for women drug users are poorly documented. In 2008, in Tijuana, Mexico, we conducted an exploratory qualitative study of migration, deportation, and drug abuse by interviewing 12 Mexican injection-drug-using women reporting U.S. deportation. Women reported heavy drug use before and after deportation, but greater financial instability and physical danger following deportation than when in the United States. We identified an unmet need for health and social services among deported drug-using women, including HIV prevention, drug treatment, physical and mental health services, and vocational training. Binational coordination is needed to help deported women resettle in Mexico.

Injection drug use as a mediator between client-perpetrated abuse and HIV status among female sex workers in two Mexico-US border cities.

We examined relationships between client-perpetrated emotional, physical, and sexual abuse, injection drug use, and HIV-serostatus among 924 female sex workers (FSWs) in Tijuana and Ciudad Juarez, two large Mexico-US border cities. We hypothesized that FSWs' injection drug use would mediate the relationship between client-perpetrated abuse and HIV-seropositivity. The prevalence of client-perpetrated emotional, physical, and sexual abuse in the past 6 months was 26, 18, and 10% respectively; prevalence of current injection drug use and HIV was 12 and 6%, respectively. Logistic regression analyses revealed that client-perpetrated sexual abuse was significantly associated with HIV-seropositivity and injection drug use, and that injection drug use was positively associated with HIV-seropositivity. Injection drug use partially mediated the relationship between client-perpetrated sexual abuse and HIV-seropositivity. Results suggest the need to address client-perpetrated violence and injection drug use when assessing HIV risk among FSWs.

A qualitative view of drug use behaviors of Mexican male injection drug users deported from the United States.

Deportees are a hidden yet highly vulnerable and numerous population. Significantly, little data exists about the substance use and deportation experiences of Mexicans deported from the United States. This pilot qualitative study describes illicit drug use behaviors among 24 Mexico-born male injection drug users (IDUs), ≥ 18 years old, residing in Tijuana, Mexico who self-identified as deportees from the United States. In-person interviews were conducted in Tijuana, Mexico in 2008. Content analysis of interview transcripts identified major themes in participants' experiences. Few participants had personal or family exposures to illicit drugs prior to their first U.S. migration. Participants reported numerous deportations. Social (i.e., friends/family, post-migration stressors) and environmental factors (e.g., drug availability) were perceived to contribute to substance use initiation in the U.S. Drugs consumed in the United States included marijuana, heroin, cocaine, methamphetamine, and crack. More than half of men were IDUs prior to deportation. Addiction and justice system experiences reportedly contributed to deportation. After deportation, several men injected new drugs, primarily heroin or methamphetamine, or a combination of both drugs. Many men perceived an increase in their substance use after deportation and reported shame and loss of familial social and economic support. Early intervention is needed to stem illicit drug use in Mexican migrant youths. Binational cooperation around migrant health issues is warranted. Migrant-oriented programs may expand components that address mental health and drug use behaviors in an effort to reduce transmission of blood-borne infections. Special considerations are merited for substance users in correctional systems in the United States and Mexico, as well as substance users in United States immigration detention centers. The health status and health behaviors of deportees are likely to impact receiving Mexican communities. Programs that address health, social, and economic issues may aid deportees in resettling in Mexico.

Factors associated with drug-related harms related to policing in Tijuana, Mexico.

OBJECTIVE: To assess factors associated with drug-related harms related to policing among injection drug users (IDUs) in Tijuana, Mexico. METHODS: IDUs who were over 18 years old and had injected drugs within the last six months were recruited via respondent-driven sampling and underwent questionnaires and testing for HIV (human immunodeficiency virus), syphilis and TB (tuberculosis). Random effects logistic regression was used to simultaneously model factors associated with five drug-related harms related to policing practices in the prior six months (i.e., police led them to rush injections; affected where they bought drugs; affected locations where they used drugs; feared that police will interfere with their drug use; receptive syringe sharing). RESULTS: Of 727 IDUs, 85% were male; median age was 38 years. Within the last 6 months, 231 (32%) of IDUs reported that police had led them to rush injections, affected where they bought or used drugs or were very afraid police would interfere with their drug use, or shared syringes. Factors independently associated with drug-related harms related to policing within the last six months included: recent arrest, homelessness, higher frequencies of drug injection, use of methamphetamine, using the local needle exchange program and perceiving a decrease in the purity of at least one drug. CONCLUSIONS: IDUs who experienced drug-related harms related to policing were those who were most affected by other micro and macro influences in the physical risk environment. Police education programs are needed to ensure that policing practices do not exacerbate risky behaviors or discourage protective behaviors such as needle exchange program use, which undermines the right to health for people who inject drugs.

Not sold here: limited access to legally available syringes at pharmacies in Tijuana, Mexico.

BACKGROUND: Sterile syringe access is a critical component of HIV prevention programs. Although retail pharmacies provide convenient outlets for syringe access, injection drug users (IDUs) may encounter barriers to syringe purchase even where purchase without a prescription is legal. We sought to obtain an objective measure of syringe access in Tijuana, Mexico, where IDUs report being denied or overcharged for syringes at pharmacies. METHODS: Trained "mystery shoppers" attempted to buy a 1 cc insulin syringe according to a predetermined script at all retail pharmacies in three Tijuana neighborhoods. The same pharmacies were surveyed by telephone regarding their syringe sales policies. Data on purchase attempts were analyzed using basic statistics to obtain an objective measure of syringe access and compared with data on stated sales policies to ascertain consistency. RESULTS: Only 46 (28.4%) of 162 syringe purchase attempts were successful. Leading reasons for unsuccessful attempts were being told that the pharmacy didn't sell syringes (35.3%), there were no syringes in stock (31.0%), or a prescription was required (20.7%). Of 136 pharmacies also surveyed by telephone, a majority (88.2%) reported selling syringes but only one-third (32.5%) had a successful mystery shopper purchase; the majority of unsuccessful purchases were attributed to being told the pharmacy didn't sell syringes. There was similar discordance regarding prescription policies: 74 pharmacies said in the telephone survey that they did not require a prescription for syringes, yet 10 of these pharmacies asked the mystery shopper for a prescription. CONCLUSIONS: IDUs in Tijuana have limited access to syringes through retail pharmacies and policies and practices regarding syringe sales are inconsistent. Reasons for these restrictive and inconsistent practices must be identified and addressed to expand syringe access, reduce syringe sharing and prevent HIV transmission.

Pandemic (H1N1) 2009 Surveillance in Marginalized Populations, Tijuana, Mexico.

To detect early cases of pandemic (H1N1) 2009 infection, in 2009 we surveyed 303 persons from marginalized populations of drug users, sex workers, and homeless persons in Tijuana, Mexico. Six confirmed cases of pandemic (H1N1) 2009 were detected, and the use of rapid, mobile influenza testing was demonstrated.

Latent tuberculosis among persons at risk for infection with HIV, Tijuana, Mexico.

Because there is little routine tuberculosis (TB) screening in Mexico, the prevalence of latent TB infection (LTBI) is unknown. In the context of an increasing HIV epidemic in Tijuana, Mexico, understanding prevalence of LTBI to anticipate emergence of increased LTBI reactivation is critical. Therefore, we recruited injection drug users, noninjection drug users, female sex workers, and homeless persons for a study involving risk assessment, rapid HIV testing, and TB screening. Of 503 participants, the overall prevalences of TB infection, HIV infection, and TB/HIV co-infection were 57%, 4.2%, and 2.2%, respectively; no significant differences by risk group (p>0.05) were observed. Two participants had TB (prevalence 398/100,000). Incarceration in Mexico (odds ratio [OR] 2.28), age (OR 1.03 per year), and years lived in Tijuana (OR 1.02 per year) were independently associated with TB infection (p<0.05). Frequent LTBI in marginalized persons may lead to increases in TB as HIV spreads.

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.