International Journal of Drug Policy - 2014

Volume 25 Issue 3 May 2014

Issue link:

Contents of this Issue


Page 25 of 153

526 N. Kori et al. / International Journal of Drug Policy 25 (2014) 525–532 in the study visit immediately prior to seroconversion (Brouwer, Rusch, et al., 2012). This strong clustering of incident HIV cases overlapped with and largely encompassed Tijuana's red light dis- trict or 'Zona Roja,' which is well known for sex tourism. The Zona Roja is made up of several blocks within a neighborhood abut- ting the main Mexico/U.S. border crossing, although it is difficult to define the exact size of the area as the outer edges are fluid. Within this sex work tolerance zone, prostitution is quasi-legal as long as sex workers obtain a permit requiring monthly HIV testing and quarterly screening for sexually transmitted infections (STIs) (Sirotin et al., 2010). Cost (approximately $360/year) and fear of testing HIV positive are main reasons why many sex workers (>50%) operate without a permit (Bucardo, Semple, Fraga-Vallejo, Davila, & Patterson, 2004). While police stations are spread throughout Tijuana, the area around the HIV hotspot is heavily patrolled. Police interactions have been associated with risky injection practices (i.e. rushed injection, needle sharing, utilization of shooting galleries) among IDUs in this and other cities (Cooper et al., 2011; Miller et al., 2008; Pollini et al., 2008; Rachlis et al., 2010). Counter balancing this, harm reduction services, including needle exchange, are also concentrated in this area, with mobile clinics serving distant neighborhoods. Another factor featuring prominently in the risk environment of Tijuana is mobility. IDU populations are known to be highly mobile, traveling within cities and across international borders in search of work and safety, to escape social controls, and to access illicit drugs (Rachlis et al., 2007). In a recent study, we found that approximately 25% of IDUs in Tijuana regularly travel ≥3 km between residence and injection site and 18% had crossed the Mexico–U.S. border in the past 6 months (Brouwer, Lozada, et al., 2012). Intra-urban and cross-border mobility may be a factor in transmission of HIV because IDUs who travel are connecting to, and may be engaging in high-risk behaviors, with individuals in different sexual and drug use networks. The present analysis examines a variety of individual and con- textual determinants thought to be associated with injecting within the HIV incidence 'hotspot.' We hypothesized that (1) IDUs who inject in the hotspot are likely to have traveled farther from their place of residence compared to those who inject outside the hotspot; and (2) the geographical overlap of the 'hotspot' with the red light district may be associated with increased probability that IDUs primarily injecting in this area were more likely to engage in commercial sex (i.e. purchasing or selling sexual services) and/or to have experienced a rushed injection because of the increased police presence (i.e. more frequent patrols) within the Zona Roja. Thus, in this manuscript we explore the association between drug injection location and risk behaviors in order to understand factors that might be influencing HIV transmission in this area compared to other parts of Tijuana. Methods Study population Between April 2006 and April 2007, 1056 IDUs living in Tijuana were recruited into a prospective study of factors associated with HIV, syphilis, and tuberculosis (TB) infections (Proyecto El Cuete, Phase III). Eligibility criteria were being at least 18 years of age, injecting illicit drugs within the previous month (confirmed by inspection of injection track marks), ability to speak English or Spanish, and reporting no plans to permanently move away from Tijuana within the next 18 months. Using respondent-driven samp- ling (RDS), a group of "seeds" was initially selected based on diversity of neighborhoods, gender, age, and drug preferences (Heckathorn, 1997). Seeds were then given recruitment coupons to refer up to three peers to the study and additional waves of recruit- ment continued until the sample size was reached. Participants received monetary compensation for their time of approximately $10 US dollar to complete the baseline interview and also $5 for each eligible male recruit or $6 for each eligible female recruit that they referred. They received more money for female recruits because networks of female IDUs are more difficult to access in this city than male IDUs. Data collection and laboratory testing Initial recruitment of seeds and subsequent interviews were conducted by local outreach workers in a mobile office in a mod- ified recreational vehicle and a storefront office. At baseline and each six month follow-up, participants completed an interviewer- administered survey eliciting information on sociodemographic, behavioral, and contextual characteristics related to drug use and sexual behaviors occurring over their lifetime and within the past six months. Additional domains included HIV knowledge, incar- ceration history, and health care utilization. For this study analysis, only the baseline data was used, thus the analysis is cross-sectional. During study visits, locations where participants live (or most often sleep at night), work/earn money, obtain drugs, and inject drugs were plotted on paper-maps, with the interviewers help- ing to narrow down locations from colonias (or neighborhoods) to more precise locations based on a discussion of landmarks and major crossroads. Geosptaial data were later digitized in ArcMap 9.3 (ESRI, Redlands, CA) (Brouwer, Rusch, et al., 2012). Verbal and written consent was sought from all participants and the study was approved by the institutional review board at the University of California, San Diego and the Ethics Committee of the Tijuana General Hospital. The 'Determine' rapid HIV antibody test (Abbott Pharmaceut- icals, Boston, MA) was administered to detect the presence of HIV antibodies. All reactive samples were confirmed using an HIV- 1 enzyme immunoassay and immunofluorescence assay. Syphilis serology used the rapid plasma regain (RPR) test (Macro-Vue; Becton Dickenson, Cockeysville, MD). RPR-positive samples were subjected to confirmatory testing using the Treponema pallidum particle agglutination assay (TPPA; Fujirebio, Wilmington, DE). Syphilis titers ≥1:8 were considered to be consistent with active infection, whereas the remainder of positive specimens was con- sidered to reflect lifetime, rather than current infection. Specimen testing was conducted by the San Diego County Health Department. Participants testing positive for syphilis were treated on site and those testing positive for HIV or TB were referred to the Tijuana municipal health clinic for free follow-up care. Variable definitions Participants were defined as injecting in the HIV incidence 'hotspot, an area of approximately 1.95 km 2 ' if they most fre- quently injected within a three standard deviational ellipse of the cohort's incident HIV cases (Fig. 1). Participants were asked, "In the past 3 months, where did you shoot up the most often?" and their responses were mapped to capture the location where they most frequently injected drugs. The HIV hotspot abuts the busy San Ysidro Mexico/U.S. border crossing and overlaps Tijuana's most well-known red light district (Zona Roja in Spanish). All variables used in this analysis were dichotomized with the exception of age, age at first injection, and number of personal contacts who have died from AIDS, which were left continuous. Educational level was divided by secondary education or higher (at least 9th grade) vs. less than a secondary education because this is the level to which education is compulsory in Mexico. Homelessness was defined as sleeping in a car, abandoned building, shelter, shooting gallery,

Articles in this issue

view archives of International Journal of Drug Policy - 2014 - Volume 25 Issue 3 May 2014