Abstract
Objective
To examine associations between migration and sexually transmitted infection (STI) prevalence among Mexican female sex workers (FSW).
Methods
FSW aged ≥18 years in Tijuana, Baja California (BC) underwent interviews and testing for HIV, syphilis, gonorrhea and Chlamydia. Multivariate logistic regressions identified correlates of STI.
Results
Of 471 FSW, 79% were migrants to BC. Among migrant FSW, prevalence of HIV, syphilis, gonorrhea, Chlamydia, and any STI was 6.6%, 13.2%, 7.8%, 16.3%, and 31.1% vs. 10.9%, 18.2%, 13.0%, 19.0%, and 42.4% among FSW born in BC. A greater proportion of migrant FSW were registered with local health services and were ever tested for HIV. Migrant status was protective for any STI in unadjusted models (Unadj. OR: 0.61, 95%CI: 0.39, 0.97). In multivariate models controlling for confounders, migrant status was not associated with an elevated odds of STI acquisition and trended towards a protective association.
Conclusions
Unexpectedly, migrant status (vs. native-born status) appeared protective for any STI acquisition. It is unclear which social or economic conditions may protect against STI and whether these erode over time in migrants. Additional research is needed to inform our understanding of whether or how geography, variations in health capital, or social network composition and information sharing attributes can contribute to health protective behaviors in migrant FSW. By capitalizing on such mechanisms, efforts to preserve protective health behaviors in migrant FSW will help control STI in the population and may lead to the identification of strategies that are generalizable to other FSW.
Keywords: migration, female sex workers, sexually transmitted infections, HIV, Mexico
INTRODUCTION
Sexually transmitted infections (STI) are highly prevalent among female sex workers (FSW) residing in Tijuana and Ciudad Juarez, cities on the U.S.-Mexico border that permit prostitution1, 2. In Tijuana, 5,000 to 9,000 women are registered FSW1,3. In a study of 924 FSW in Tijuana and Ciudad Juarez, 6% tested positive for HIV antibodies, 13% for Chlamydia, 6% for gonorrhea, 14% for syphilis titers ≥1:8, and 27% for any STI2. Those findings starkly contrast those from earlier studies of Mexican FSW which reported HIV prevalence estimates below 1%4. HIV prevalence is increasing in Tijuana; in 2005, as many as 1 per 125 persons in the 15–49 years age group was estimated to be HIV-infected5.
Migrants may experience economic, physical, and sexual vulnerabilities related to separation from social networks; isolation may result in increased and risky sexual and substance use behaviors6. In the U.S., migrant men are at risk for HIV6, 7; similar studies on migrant females in either Mexico or the U.S. are largely absent. Mexico has a long history of domestic and international migration8, 9; little is known about the relationship between migration and STI prevalence among FSW residing in border communities.
We focus on Tijuana because Baja California borders California; it is a popular destination for Mexican migrants10. Tijuana and San Diego are the largest sister cities in the Southern California region with more than 5.9 million residents; they host the busiest international border crossing in the world11, 12 13. San Diego's tourists often visit Tijuana, some consuming quasi-legal sexual services. More than 42,000 Tijuana residents visit the U.S. daily for work or pleasure14. Infectious disease epidemics have significant public health impacts for both countries.
In Mexico, AIDS is becoming a feminized condition: women accounted for 21% of newly reported AIDS cases in 2006 (vs. 16% between 1983–2006)15. We examined migration as a correlate of four STI in a sample of FSW residing in Tijuana. We hypothesized that migration to Tijuana, a potentially high risk social process, would increase the likelihood that migrant FSW would test positive for HIV, gonorrhea, Chlamydia, and syphilis as compared to FSW born in Baja California.
METHODS
Study Sample
We analyzed baseline data collected between January, 2004-March 2005 from one site of a multisite behavioral intervention that trained participating FSW on methods to reduce HIV/STI. Data were restricted to Mexican FSW interviewed in Tijuana (n=471). We selected Tijuana based on the state's historically high annual rate of growth (2.4% in the 2005 vs. 1.1% for the other study site, Chihuahua). Study methods have been described elsewhere16. Eligibility requirements included being ≥18 years, giving informed consent, having traded sex for drugs, money, or other material benefits in the prior 2 months, having had unprotected vaginal sex with at least 1 client in the prior 2 months. HIV positive women were excluded, since HIV incidence was a primary outcome of the behavioral intervention. Recruitment occurred at municipal and community health clinics, via street outreach, and by referrals from other FSW.
Dependent Variables: Laboratory Testing for STI
Participants provided blood samples and a cervical swab at baseline to test for STI. HIV antibody was initially assessed via the “Determine” rapid HIV antibody test using plasma (Abbot Pharmaceuticals, Boston, MA. USA); further testing was conducted for all reactive samples using the HIV-1 antibody by EIA and Western Blot. Blood samples were also initially tested for syphilis antibody using rapid plasma reagin test (RPR) and confirmatory testing relied on the Treponema pallidum hemagglutinin assay (TPHA) (Fujirebio, Wilmington, DE). RPR titers ≥1:8 were considered to be reflective of active infection. Neisseria gonorrhoeae and Chlamydia trachomatis were identified with vaginal swabs collected by trained nurses who used the Aptima Combo 2 collection device (Genprobe, San Diego, CA), as it allows for a direct target-amplified nucleic probe test. Specimens were shipped to the San Diego County Department of Health. Women testing positive were provided with pre and post-test counseling and referred to local municipal health clinics for free medical care.
Independent Variables
Participants responded to a 45-minute interviewer-administered survey in Spanish in a private location to ensure confidentiality16. We examined characteristics of FSW, disaggregating data for women born in Baja California (i.e., natives) and women born in any another Mexican state (excluding Baja California) (i.e., migrants to BC). Dichotomous variables were: current age, currently partnered, dependent children, educational attainment, homeowner, English language skills, current work situation (street worker, dance host, bar maid), registered with municipal health services, male clients use/inject drugs, financial reliance on male clients (e.g., women's receipt of money for meals, transportation, shelter, and clothing beyond funds received for sexual interactions), has U.S. clients, condoms carried at baseline interview, access to free condoms, unprotected vaginal or anal or oral sex with clients in the prior month, condom use during anal or oral sex during prior 6 months, unprotected vaginal, anal, or oral sex with spouse/common law partner, ever tested for HIV, and ever used illegal drugs before/during sex. Continuous variables were mean number of years worked as FSW and mean number of regular and casual clients. Variables were selected based on the extant literature; individual and client factors contribute to STI prevalence in FSW17, 18.
Statistical Methods
The relationship between migrant status, sociodemographic characteristics, sexual behaviors and the presence of HIV or STI were examined separately and in aggregate as any STI, via contingency tables. Differences in categorical data were assessed using chi-square tests. Univariate and multivariate logistic regression models were constructed to test associations between migrant status and HIV and other STI positivity. Multivariate logistic regression models were developed using a manual procedure; variables attaining significance at p≤0.10 in at least one univariate model were considered in multivariate models that adjusted for other covariates.
RESULTS
Sociodemographic Characteristics
Of 471 Mexican-born FSW, 79% migrated to Baja California (BC) (referred to hereafter as migrant FSW); the remaining 21% were natives to BC (referred to as native FSW) (Table 1). A similar proportion of migrants originated from northern and central Mexico (41.4% vs. 48.7%, respectively); southern states were underrepresented (10%) (data not shown). Low educational attainment was prevalent among migrant FSW; nearly one-half of BC natives spoke some English. Women worked ~5 years as FSW and reported ~5 male clients in the prior month. Native FSW were more likely to report working on the street and to have ever used illicit drugs before/during sex compared to migrants. Migrant FSW were more likely to report using a condom if engaging in anal sex during the prior 6 months. Significantly, nearly three quarters of migrant FSW (72%) and two-thirds of BC natives (62%) (p=0.004, data not shown) indicated not engaging in anal sex during the prior 6 months.
Table 1.
Sociodemographic Characteristics, Sexual Behaviors, Client Traits, and Sexually Transmitted Infections, Mexico-Born Female Sex Workers by Migrant Status, Tijuana, Baja California.
| Characteristics | Overall Sample (n=471) | Baja California Native (n=101) 21% | Migrant to Baja California (n=370) 79% | P-value |
|---|---|---|---|---|
| INDIVIDUAL TRAITS | ||||
| Age | ||||
| 18–34 | 59.9 | 66.3 | 58.1 | |
| 35–64 | 40.1 | 33.7 | 41.9 | 0.14 |
| Has spouse/common-law partner | 32.3 | 37.6 | 30.8 | 0.19 |
| Have Dependent Children | 92.4 | 91.1 | 92.7 | 0.59 |
| Educational Attainment | ||||
| 0–6 years | 50.5 | 39.6 | 53.5 | |
| 7–20 years | 49.5 | 60.4 | 46.5 | 0.01 |
| Owns home | 17.8 | 15.8 | 18.4 | 0.56 |
| Speaks any English | 32.9 | 46.5 | 29.2 | <0.01 |
| Mean # of years worked as FSW (sd) | 4.87 (6.3) | 5.1 (5.9) | 4.8 (6.4) | 0.68 |
| Current Work Situation | ||||
| Street Worker | 42.3 | 57.4 | 38.1 | <0.01 |
| Dance Host | 31.6 | 23.8 | 33.8 | 0.06 |
| Bar Maid | 17.8 | 12.9 | 19.2 | 0.14 |
| Registered with Tijuana Municipal Health Services | 28.0 | 15.8 | 31.4 | <0.01 |
| Ever use illegal drugs before/during sex | 34.3 | 47.0 | 30.8 | <0.01 |
| CLIENT TRAITS | ||||
| Mean # regular male clients last month (sd) | 5.3 (10.6) | 5.8 (10.9) | 5.2 (10.5) | 0.63 |
| Mean # casual male clients last month (sd) | 15.4 (25.3) | 12.6 (15.7) | 16.2 (27.3) | 0.22 |
| Male clients use drugs | ||||
| None | 18.5 | 17.8 | 18.7 | |
| Any | 81.5 | 82.2 | 81.4 | 0.85 |
| Male clients inject drugs | ||||
| None | 49.3 | 56.4 | 47.3 | |
| Any | 50.7 | 43.6 | 52.7 | 0.10 |
| Financial reliance on male clients | ||||
| None | 42.7 | 45.5 | 41.9 | |
| Any | 57.3 | 54.5 | 58.1 | 0.51 |
| Has U.S. Clients | 77.5 | 83.2 | 76.0 | 0.12 |
| SEXUAL BEHAVIORS | ||||
| Number of condoms carried at baseline interview | ||||
| None | 88.8 | 94.1 | 87.3 | |
| Any | 11.3 | 5.9 | 12.7 | 0.06 |
| Access to free condoms | ||||
| Never | 57.3 | 53.5 | 58.4 | |
| Sometimes | 31.6 | 40.6 | 29.2 | |
| Often/ Always | 11.0 | 5.9 | 12.4 | 0.04 |
| Unprotected vaginal sex with regular or casual clients, last month | 97.7 | 100 | 97.0 | 0.08 |
| Unprotected anal sex with regular or casual clients, last month | 16.8 | 21.8 | 15.4 | 0.13 |
| Unprotected oral sex with regular or casual clients, last month | 47.1 | 54.5 | 45.1 | 0.10 |
| Unprotected vaginal sex with spouse/common law partner‡ | 73.7 | 65.8 | 76.3 | 0.20 |
| Unprotected anal sex with spouse/common law partner‡ | 21.7 | 29.0 | 19.3 | 0.22 |
| Unprotected oral sex with spouse/common law partner‡ | 51.3 | 55.3 | 50.0 | 0.57 |
| Condom use during anal sex, past 6 months | ||||
| Never/ sometimes | 21.7 | 32.7 | 18.7 | |
| Often/always/ do not have anal sex | 78.3 | 67.3 | 81.4 | <0.01 |
| Condom use during oral sex, past 6 months | ||||
| Never/ sometimes | 47.8 | 53.5 | 46.2 | |
| Often/always/ do not have oral sex | 52.2 | 46.5 | 53.8 | 0.20 |
| Spouse/common law partner has other sexual partner‡ † | 47.3 | 50.0 | 46.4 | 0.74 |
| Ever tested for HIV | 65.8 | 56.4 | 68.4 | 0.03 |
| SEXUALLY TRANSMITTED INFECTIONS | ||||
| Tested HIV-Positive | ||||
| No | 92.5 | 89.1 | 93.4 | |
| Yes | 7.5 | 10.9 | 6.6 | 0.15 |
| Test Positive for Chlamydia | ||||
| No | 83.2 | 81.0 | 83.8 | |
| Yes | 16.9 | 19.0 | 16.3 | 0.52 |
| Test Positive for Gonorrhea | ||||
| No | 91.0 | 87.0 | 92.2 | |
| Yes | 9.0 | 13.0 | 7.8 | 0.11 |
| Syphilis Titer ≥1:8 | ||||
| No | 85.8 | 81.8 | 86.8 | |
| Yes | 14.3 | 18.2 | 13.2 | 0.21 |
| Tested Positive for any of above STI | ||||
| No | 66.5 | 57.6 | 68.9 | |
| Yes | 33.6 | 42.4 | 31.1 | 0.03 |
NOTES: comparisons were made between Baja California migrants and Baja California natives. Estimates may not add to 100% due to rounding.
Restricted to women with a spouse/common law partner;
During the duration of the relationship
Prevalence of STI and HIV
Migrant FSW were less likely than native FSW to test positive for any STI (31.1% vs. 42.4%, respectively, p=0.03; Table 1). Migrant and native FSW did not differ significantly in terms of prevalence of HIV (6.6% and 10.9%, respectively), Chlamydia, or gonorrhea. Migrant FSW were more likely than BC natives to report ever being tested for HIV (68.4% vs. 56.4%, respectively).
Correlates of HIV and Other STI
In univariate logistic regressions, migrant status was protective against any STI (Table 2). Migrant FSW were about two-thirds as likely to be infected with any STI (Unadj. ORs: 0.61, 95%CI: 0.39, 0.97). Migrant FSW were not significantly different from natives in their odds of being infected with HIV, gonorrhea, active syphilis, or Chlamydia.
Table 2.
Univariate Logistic Regressions: Factors Associated with Sexually Transmitted Infections, Among Female Sex Workers Ages 18 and Older, Tijuana, BC
| Any STI Unadj. OR (95% CI) | HIV Unadj. OR (95% CI) | Syphilis Titer ≥1:8 Unadj. OR (95% CI) | Gonorrhea Unadj. OR (95% CI) | Chlamydia Unadj. OR (95% CI) | |
|---|---|---|---|---|---|
| INDIVIDUAL TRAITS | |||||
| Migrant to Baja California | 0.61** (0.39, 0.97) | 0.58 (0.27, 1.22) | 0.68 (0.38, 1.24) | 0.57 (0.28, 1.15) | 0.83 (0.47, 1.47) |
| Age 35–64 | 0.68* (0.45, 1.03) | 0.89 (0.43, 1.81) | 0.95 (0.55, 1.63) | 0.86 (0.44, 1.67) | 0.51** (0.30, 0.88) |
| Have Spouse/Steady Partner | 1.23 (0.82, 1.86) | 0.70 (0.32, 1.54) | 1.17 (0.67, 2.02) | 1.08 (0.55, 2.12) | 1.22 (0.73, 2.04) |
| Dependent child | 1.11 (0.53, 2.33) | 0.89 (0.26, 3.05) | 0.79 (0.31, 1.98) | 0.74 (0.25, 2.23) | 2.27 (0.68, 7.60) |
| 7–20 years of Schooling | 1.03 (0.70, 1.53) | 0.50* (0.24, 1.04) | 1.10 (0.65, 1.86) | 0.86 (0.45, 1.63) | 1.18 (0.72, 1.92) |
| Owns home | 0.28*** (0.15, 0.53) | 0.12** (0.02, 0.93) | 0.41** (0.17, 1.00) | 0.10** (0.01, 0.75) | 0.27*** (0.11, 0.69) |
| Speaks any English | 1.37 (0.91, 2.06) | 1.08 (0.52, 2.23) | 2.30*** (1.35, 3.92) | 1.54 (0.80, 2.97) | 0.81 (0.47, 1.38) |
| Number of years worked as FSW | 1.00 (0.97, 1.03) | 1.02 (0.98, 1.07) | 1.03 (0.99, 1.07) | 0.94 (0.88, 1.02) | 0.97 (0.93, 1.02) |
| Current Work Situation | |||||
| Street Worker | 1.32 (0.89, 1.96) | 1.29 (0.65, 2.57) | 2.14*** (1.26, 3.65) | 3.68*** (1.82, 7.41) | 1.02 (0.62, 1.67) |
| Dance Host | 0.66* (0.43, 1.02) | 0.75 (0.34, 1.64) | 0.56* (0.30, 1.04) | 0.22*** (0.08, 0.62) | 0.86 (0.50, 1.47) |
| Bar Maid | 0.99 (0.59, 1.65) | 1.43 (0.62, 3.26) | 0.61 (0.28, 1.34) | 0.62 (0.24, 1.64) | 0.93 (0.49, 1.79) |
| Registered with Tijuana Municipal Health Services | 0.59** (0.38, 0.39) | 0.31** (0.11, 0.90) | 0.47** (0.24, 0.92) | 0.18*** (0.06, 0.60) | 0.87 (0.50, 1.52) |
| Ever used illegal drugs before/during sex | 2.80*** (1.86, 4.21) | 3.16** (1.56, 6.41) | 2.83*** (1.66, 4.82) | 4.18*** (2.12, 8.24) | 1.52* (0.92, 2.51) |
| CLIENT TRAITS | |||||
| # regular male clients, past month | 1.00 (0.98, 1.02) | 0.96 (0.88, 1.05) | 1.01 (0.99, 1.03) | 1.00 (0.97, 1.03) | 0.98 (0.94, 1.02) |
| # casual male clients, past month | 0.99 (0.98, 1.00) | 0.98 (0.95, 1.01) | 0.99 (0.98, 1.01) | 0.99 (0.97, 1.01) | 1.00 (0.98, 1.01) |
| Male clients use drugs | 1.04 (0.62, 1.72) | 1.80 (0.62, 5.24) | 1.09 (0.54, 2.19) | 2.17 (0.75, 6.26) | 1.24 (0.64, 2.43) |
| Male clients inject drugs | 0.81 (0.55, 1.20) | 0.91 (0.46, 1.81) | 0.40*** (0.23, 0.70) | 1.73* (0.89, 3.37) | 0.97 (0.60, 1.59) |
| Financial reliance on any male clients | 1.21 (0.82, 1.81) | 3.17*** (1.35, 7.41) | 1.04 (0.61, 1.77) | 0.91 (0.48, 1.74) | 1.15 (0.70, 1.90) |
| Has U.S. Clients | 1.83 (1.10, 3.04) | 0.94 (0.42, 2.15) | 5.03 (1.78, 14.20) | 2.81* (0.98, 8.09) | 1.48 (0.78, 2.82) |
| SEXUAL BEHAVIORS | |||||
| Any condoms carried at baseline interview | 1.32 (0.72, 2.40) | 0.21 (0.03, 1.59) | 0.95 (0.41, 2.21) | 1.70 (0.71, 4.05) | 1.20 (0.57, 2.51) |
| Access to free condoms | |||||
| Never | 0.99 (0.67, 1.47) | 1.13 (0.56, 2.29) | 0.87 (0.51, 1.47) | 0.87 (0.45, 1.65) | 1.31 (0.79, 2.17) |
| Sometimes | 1.11 (0.73, 1.69) | 0.98 (0.47, 2.06) | 1.62 (0.95, 2.78) | 1.41 (0.73, 2.73) | 0.89 (0.52, 1.52) |
| Never/ sometimes use condoms during anal sex, past 6 months | 1.07 (0.67, 1.71) | 0.88 (0.37, 2.08) | 1.00 (0.53, 1.90) | 1.56 (0.77, 3.19) | 1.34 (0.76, 2.36) |
| Never/ sometimes use condoms during oral sex, past 6 months | 1.02 (0.69, 1.51) | 1.30 (0.65, 2.60) | 1.09 (0.65, 1.84) | 1.46 (0.77, 2.79) | 0.97 (0.59, 1.58) |
| Any unprotected vaginal sex with regular or casual client, last month | 2.03 (0.23, 18.35) | 0.32, (0.03, 2.94) | NA | NA | NA |
| Any unprotected anal sex with regular or casual client, last month | 0.88 (0.52, 1.49) | 1.01 (0.41, 2.52) | 0.88 (0.43, 1.81) | 1.02 (0.43, 2.39) | 1.12 (0.59, 2.12) |
| Any unprotected oral sex with regular or casual clients, last month | 1.38* (0.94, 2.05) | 1.17 (0.59, 2.34) | 1.34 (0.79, 2.27) | 2.59*** (1.30, 5.13) | 1.50 (0.91, 2.45) |
| Unprotected vaginal sex with spouse/common law partner‡, past month | 0.81 (0.38, 1.73) | 1.23 (0.25, 6.20) | 1.24 (0.43, 3.61) | 0.41 (0.13, 1.28) | 0.54 (0.22, 1.31) |
| Unprotected anal sex with spouse/common law partner‡, past month | 1.16 (0.52, 2.57) | 1.02 (0.20, 5.18) | 2.13 (0.81, 5.59) | NA | 0.95 (0.35, 2.58) |
| Unprotected oral sex with spouse/common law partner‡, past month | 0.86 (0.44, 1.68) | 0.74 (0.19, 2.86) | 1.85 (0.73, 4.66) | 1.28 (0.42, 3.87) | 0.65 (0.28, 1.48) |
| Spouse/common law partner has other sexual partner‡ †, | 0.71 (0.32, 1.57) | 1.1 (0.21, 5.70) | 0.45 (0.15, 1.41) | 1.73 (0.46, 6.50) | 1.26 (0.49, 3.27) |
| Ever tested for HIV | 0.92 (0.61, 1.38) | 0.47** (0.24, 0.94) | 0.72 (0.42, 1.23) | 0.82 (0.42, 1.58) | 1.06 (0.63, 1.77) |
NOTES: p ≤0.10,
p ≤ 0.05
p ≤ 0.01
Restricted to women with a spouse/common law partner;
During the duration of the relationship.
The relationship between other factors and STI varied. Street workers were more likely to test positive for active syphilis and gonorrhea, whereas dance hosts were less likely to test positive for any STI, syphilis, and gonorrhea. Registration with the city's municipal health services was significantly protective against any STI, active syphilis, and gonorrhea. Financial reliance on male clients raised women's odds of testing positive for HIV (unadj. OR: 3.17, 95%CI: 1.35, 7.41). A history of illicit drug use before or during sexual activities was significantly associated with each infection except chlamydia; odds ratios ranged from 2.80 for any STI, 3.16 for HIV, to 4.18 for gonorrhea (all P<0.05). Having ever been tested for HIV was associated with reduced odds of testing positive for HIV (OR: 0.47).
In multivariate logistic regressions that controlled for other covariates, although the migrant status indicator remained protective against HIV, gonorrhea, chlamydia and any STI, this variable lost statistical significance after adjustment (Table 3). This finding was explained in part by the significant role of illicit drug use prior to or during sexual encounters. FSW who had ever used illicit drugs before or during sex were at significantly higher risk of testing positive for any STI (adj.OR: 2.42), HIV (adj.OR: 2.53), active syphilis (adj.OR: 2.24), and gonorrhea (adj.OR: 3.04) (all p<0.05).
Table 3.
Factors Independently Associated with Sexually Transmitted Infections, Female Sex Workers Ages 18 and Older, Tijuana, BC
| Any STI Adj. OR (95% CI) | HIV Adj. OR (95% CI) | Syphilis Titer ≥1:8 Adj. OR (95% CI) | Gonorrhea Adj. OR (95% CI) | Chlamydia Adj. OR (95% CI) | |
|---|---|---|---|---|---|
| INDIVIDUAL TRAITS | |||||
| Migrant to Baja California (vs. BC native) | 0.72 (0.44, 1.17) | 0.74 (0.32, 1.74) | 1.10 (0.57, 2.11) | 0.72 (0.35, 1.49) | 0.87 (0.48, 1.55) |
| Age 35–64 (vs. age 18–34) | Ns | -- | -- | -- | 0.53* (0.31, 0.91) |
| 7–20 years of Schooling (vs. 0–6 years) | -- | 0.42* (0.19, 0.90) | -- | -- | -- |
| Own home (vs. not homeowner) | 0.32** (0.16, 0.62) | Ns | -- | 0.13* (0.02, 0.99) | 0.28* (0.11, 0.71) |
| Speak English (vs. do not speak English) | -- | -- | 1.87* (1.03, 3.41) | -- | -- |
| Currently Employed as a Dance Host (vs. not employed as a dance host) | -- | -- | -- | 0.30* (0.10, 0.86) | -- |
| Currently Employed as a Bar Maid (vs. not employed as a bar maid) | -- | -- | -- | -- | -- |
| Currently Employed as a Streetwalker (vs. not employed as a streetwalker) | -- | -- | Ns | -- | -- |
| Registered with Municipal Health Services (vs. not registered) | -- | -- | -- | -- | -- |
| CLIENT TRAITS | |||||
| Has U.S. clients (vs. no U.S. clients) | Ns | -- | 4.33** (1.48, 12.62) | -- | -- |
| Male clients inject drugs (vs. no male clients who inject drugs) | -- | -- | 0.28** (0.16, 0.52) | -- | -- |
| Financial reliance on male clients (vs. not financially reliant on male clients) | -- | 3.71** (1.46, 9.40) | -- | -- | -- |
| SEXUAL BEHAVIORS | |||||
| Any unprotected oral sex with regular or casual clients, last month (vs. protected oral sex/no oral sex) | -- | -- | -- | -- | -- |
| Syphilis Titer ≥1:8 (vs. no syphilis titer ≥1:8) | -- | Ns | -- | -- | -- |
| Ever had HIV test (vs. never had HIV test) | -- | -- | Ns | -- | -- |
| DRUG USE | |||||
| Ever use illegal drugs before/during sex (vs. never used illegal drugs before/during sex) | 2.42** (1.58, 3.70) | 2.53* (1.18, 5.43) | 2.24** (1.25, 4.03) | 3.04* (1.51, 6.11) | -- |
NOTES: p § 0.05
p § 0.01;
NS: refers to not significant. Dashes (--) refer to variable not included in model
The relationships between other covariates and all STI varied (Table 3). Older age was protective against Chlamydia, greater education was protective against HIV, and homeownership was protective against any STI, gonorrhea, and Chlamydia. English language was associated with an increased odds of active syphilis as was having an American client. Working as a dance host was associated with reduced odds of gonorrhea. Financial dependence was significantly associated with increased odds of HIV infection.
DISCUSSION
Mexican-born migrant FSW presented a strikingly different profile of STI and associated risks compared to BC native FSW. Surprisingly, migration was not associated with a higher prevalence of STI among our sample of high risk FSW and trended towards a protective effect, which was contrary to our hypothesis. Our findings may signal changes in migration patterns among Mexican FSW not observed in the extant literature19 or differences between FSW and other migrants, since studies of Mexican migrants have under-represented women. Our findings have important implications for HIV/STI prevention and program planning in this resource-constrained setting.
The finding that migration was not associated with higher STI prevalence in our study was unexpected. Indeed, our findings suggested that migration may be contribute to protective mechanisms against STI infections beyond those factors that were accounted for in our study. We may have lacked statistical power in our sample to detect significant associations between migrant status and individual STI. Nevertheless, 11% and 7% of natives and migrant FSW, respectively, were infected with HIV and BC natives exhibited significantly higher levels of any STI compared to migrants (42% vs. 31%). Notably as well, a greater proportion of migrant FSW were ever tested for HIV (vs. BC natives). Additional study in a larger sample is needed to better understand the role of migration on STI acquisition in FSW residing in Mexico-US border communities.
Our findings suggest that migrant Mexican FSW may migrate with a history of protective health behaviors or experience migration-related situations that we did not measure (e.g., fewer total lifetime sexual partners or the quality/nature of social networks) that may contribute to a lower prevalence of STI. For example, in migrant sending states such as Jalisco and Michoacan, gender-based sexual roles are strictly prescribed for women and reinforced by social networks20. These conditions may foster behaviors that may reduce women's exposure to STI over the lifecourse or may instill health-promoting behaviors in FSW that are maintained post- migration. A study of Mexican male migrants in the U.S. found that health damaging behaviors (i.e., substance use) were related to the absence of traditional living arrangements and separation from family and community social norms that typically sanctioned adverse behaviors, among other factors21. Garcia's study provides evidence that social contexts may contribute to migrants' participation in unsafe behaviors. However, our current understanding of the nature of social norms and sexual roles in border communities is very limited. Investigating whether social norms, gender-based sex and social roles or risk-taking behaviors differ in border communities will inform our understanding of how social and cultural factors vary within one nation to impact STI risks among Mexican FSW.
Our findings suggest that further investigation of a “healthy migrant” effect, whereby migrants display health protective behaviors, is warranted and may occur not only in U.S. Latinos 22, 23 but potentially within national boundaries in the country of origin. Identifying the role of environment, including geography, on sexual or other risk-taking behaviors in FSW is important as is assessing how protective behaviors change over time as individuals “acculturate” to local customs and social and economic climates. Implementing a long-term study with a large migrant sample will permit us to assess the changes in interactions between individuals and their physical and social environments and to conduct a detailed examination of longitudinal changes in knowledge, attitudes, beliefs or behaviors in FSW residing on the U.S-Mexico border region.
The high prevalence of STI in our sample indicates that regular testing for HIV and other STI is critically needed to stem the HIV epidemic and its generalization to other border populations. Registering with Tijuana's Municipal Health Services (MHS) is one potential avenue for women to obtain access to regular STI testing, counseling and treatment services, all of which are beneficial to FSW and the community. Registering with MHS also provides FSW with a permit to engage in sex work in the Zona Roja (red light zone), which can confer some level of protection against police harassment for practicing sex work. However, unpublished focus group data indicates that barriers to registering with MHS include high costs for the permit and STI screening and lengthy wait times for accessing services. Reducing administrative and financial barriers to the MHS may improve participation in the program by locals and enable migrants' to continue their involvement with MHS. Formal studies on the volume or quality of services or access to or completion of treatment by infected individuals delivered by MHS may provide insight into community benefits of MHS.
Since we relied on cross-sectional self-reported baseline data; we cannot establish causality between individual correlates and the STI examined. However, standardized STI testing enabled us to more precisely identify the prevalence of infection among FSW. Our sample may not be representative of all FSW in the region or their behaviors since high-risk women were enrolled in the intervention study. Lack of data limited us from identifying risk behaviors in U.S.-migrants. Information sharing attributes of migrant FSW' networks were unmeasured, though network factors may have contributed to differential risk for STI by migrant status.
Contrary to outcomes observed in migrant males24, migrant FSW appear to have some protection against STI overall. State and programmatic efforts to ensure continued engagement in protective behaviors (e.g., regular STI screenings, consistent use of condoms, and low participation in risky behaviors including unprotected sex and illicit drug use) can help maintain a reduced risk of STI in migrant FSW. Additional research is needed to identify conditions that contribute to the endurance of protective behaviors, the conditions under which healthy behaviors erode, and factors amenable to health interventions for both native and migrant FSW.
ACKNOWLEDGMENTS
The authors respectfully acknowledge the participation of all the women in this study, and they especially thank the Mujer Segura Team for making this work possible.
FUNDING Funding for the Mujer Segura study, which yielded the data, was provided by NIMH Grant R01 MH065849 (TLP). Dr. Ojeda received funding through NIDA Grant 3R01DA019829-03S1 (SAS).
Footnotes
COMPETING INTERESTS None to declare.
ETHICS APPROVAL The protocol for the research study on which this article is based was reviewed and approved by UCSD's Human Subjects Protection Program (HRPP). The HRPP is a federally accredited Institutional Review Board (IRB) whose Federal-wide Assurance Number is FWA00004495.
REFERENCES
- 1.Patterson TL, Semple SJ, Fraga M, et al. Comparison of sexual and drug use behaviors between female sex workers in Tijuana and Ciudad Juarez, Mexico. Subst Use Misuse. 2006;41(10):12–1535. doi: 10.1080/10826080600847852. [DOI] [PubMed] [Google Scholar]
- 2.Patterson TL, Semple SJ, Staines H, et al. Prevalence and correlates of HIV infection among female sex workers in 2 Mexico-US border cities. J Infect Dis. 2008 Mar 1;197(5):728–732. doi: 10.1086/527379. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Bucardo J, Semple SJ, Fraga-Vallejo M, Davila W, Patterson TL. A qualitative exploration of female sex work in Tijuana, Mexico. Arch Sex Behav. 2004 Aug;33(4):343–351. doi: 10.1023/B:ASEB.0000028887.96873.f3. [DOI] [PubMed] [Google Scholar]
- 4.del Rio C, Sepulveda J. AIDS in Mexico: lessons learned and implications for developing countries. AIDS. 2002 Jul 26;16(11):1445–1457. doi: 10.1097/00002030-200207260-00001. [DOI] [PubMed] [Google Scholar]
- 5.Brouwer KC, Strathdee SA, Magis-Rodriguez C, et al. Estimated numbers of men and women infected with HIV/AIDS in Tijuana, Mexico. J Urban Health. 2006 Mar;83(2):299–307. doi: 10.1007/s11524-005-9027-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Organista KC, Carrillo H, Ayala G. HIV prevention with Mexican migrants: review, critique, and recommendations. J Acquir Immune Defic Syndr. 2004 Nov 1;37(Suppl 4):S227–239. doi: 10.1097/01.qai.0000141250.08475.91. [DOI] [PubMed] [Google Scholar]
- 7.Sanchez MA, Lemp GF, Magis-Rodriguez C, Bravo-Garcia E, Carter S, Ruiz JD. The Epidemiology of HIV Among Mexican Migrants and Recent Immigrants in California and Mexico. Journal of Acquired Immune Deficiency Syndrome. 2004;37(S4):S204–S214. doi: 10.1097/01.qai.0000141253.54217.24. [DOI] [PubMed] [Google Scholar]
- 8.Instituto Nacional de Estadistica Geografia e Informatica (INEGI) Perfil Sociodemografico de los Estados Unidos Mexicanos 2005. Instituto Nacional de Estadistica, Geografia, e Informatica; Aguascalientes, Ags. Mexico: 2008. [Google Scholar]
- 9.U.S. Department of Homeland Security . Yearbook of Immigration Statistics: 2006. Washington, DC: 2007. [Google Scholar]
- 10.Instituto Nacional de Estadistica Geografia e Informatica (INEGI) El INEGI Da a Conocer los Resultados Definitivos del II Conteo de Poblacion y Vivienda. 2005 http://www.inegi.gob.mx/
- 11.Instituto Nacional de Estadistica Geografia e Informatica (INEGI) Resultados Definitivos del II Conteo de Poblacion y Vivienda 2005 Para el Estado de Baja California. Mexicali, BC: 2006. [Google Scholar]
- 12.San Diego Association of Governments (SANDAG) San Diego Region Demographic and Economic Characteristics. San Diego, CA: 2006. [Google Scholar]
- 13.U.S. Department of Transportation: Bureau of Transportation Statistics . Border Crossings: U.S.-Mexico Border Crossing Data. Washington, DC: 2006. [Google Scholar]
- 14.Coubes ML. Encuesta Nacional de Empleo Urbano. El Colegio de la Frontera Norte (COLEF); Tijuana, BC: 2006. [Google Scholar]
- 15.Centro Nacional Para la Prevencion y el Control de VIH/SIDA (CENSIDA) Casos Nuevos y Acumulados de SIDA por año de Diagnóstico, Según Entidad Federativa. CENSIDA; Mexico,DF: 2007. 30 de junio. [Google Scholar]
- 16.Patterson TL, Mausbach B, Lozada R, et al. Efficacy of a brief behavioral intervention to promote condom use among female sex workers in Tijuana and Ciudad Juarez, Mexico. Am J Public Health. 2008 Nov;98(11):2051–2057. doi: 10.2105/AJPH.2007.130096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Tran TN, Detels R, Long HT, Van Phung L, Lan HP. HIV infection and risk characteristics among female sex workers in Hanoi, Vietnam. J Acquir Immune Defic Syndr. 2005 Aug 15;39(5):581–586. [PMC free article] [PubMed] [Google Scholar]
- 18.Uribe-Salas F, Conde-Glez CJ, Juarez-Figueroa L, Hernandez-Castellanos A. Sociodemographic dynamics and sexually transmitted infections in female sex workers at the Mexican-Guatemalan border. Sex Transm Dis. 2003 Mar;30(3):266–271. doi: 10.1097/00007435-200303000-00018. [DOI] [PubMed] [Google Scholar]
- 19.Consejo Estatal de Poblacion Baja California . Aspectos de la Migracion en Baja California. BC Grande Por Ti: Gobierno Del Estado de Baja California; Mexicali, BC: 2007. [Google Scholar]
- 20.Hirsch JS, Higgins J, Bentley ME, Nathanson CA. The Social Constructions of Sexuality: Marital Infidelity and Sexually Transmitted Disease-HIV Risk in a Mexican Migrant Community. American Journal of Public Health. 2002;92:1227–1237. doi: 10.2105/ajph.92.8.1227. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Garcia V. Meeting a binational research challenge: substance abuse among transnational Mexican farmworkers in the United States. J Rural Health. 2007;23(Suppl):61–67. doi: 10.1111/j.1748-0361.2007.00125.x. Fall. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Alegria M, Canino G, Shrout PE, et al. Prevalence of mental illness in immigrant and non-immigrant U.S. Latino groups. Am J Psychiatry. 2008;165(3):359–369. doi: 10.1176/appi.ajp.2007.07040704. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Franzini L, Ribble JC, Keddie AM. Understanding the Hispanic paradox. Ethn Dis. 2001;11(3):496–518. Autumn. [PubMed] [Google Scholar]
- 24.Strathdee SA, Lozada R, Ojeda VD, et al. Differential effects of migration and deportation on HIV infection among male and female injection drug users in Tijuana, Mexico. PLoS ONE. 2008;3(7):e2690. doi: 10.1371/journal.pone.0002690. [DOI] [PMC free article] [PubMed] [Google Scholar]