Introduction
This study examined the relationship between emotional, physical, and sexual abuse perpetrated by clients, injection drug use, and HIV-seropositivity among female sex workers (FSWs) in Tijuana and Ciudad (Cd.) Juarez, two large Mexico-US border cities where sex work is legally permitted within specific districts (usually referred to as the “
Zona Roja” or red light district). Singer [
1] has identified the co-occurrence of substance abuse, violence, and AIDS as the SAVA syndemic: mutually reinforcing connections between these conditions that disproportionately affect US inner-city populations living in poverty. Syndemics theory posits that endemic and epidemic conditions such as violence, substance abuse and AIDS in disadvantaged populations occur as a result of broader political, economic, and social factors [
2]. Like the SAVA syndemic in the US, FSWs in Tijuana and Cd. Juarez are experiencing disproportionate rates of violence, substance abuse, and HIV/AIDS compared to the larger Mexican population [
3‐
5]. Tijuana and Cd. Juarez are economically depressed cities situated on major drug trafficking routes [
6], making this region a nexus for violence, drug abuse, prostitution, sexual tourism, and rising rates of HIV and STIs.
HIV prevalence among FSWs in Tijuana and Cd. Juarez is significantly higher than that of the general Mexican adult population. HIV prevalence among FSWs in Tijuana was estimated to be 6% in 2005, with FSWs who inject drugs (FSW-IDUs) showing an even higher prevalence of 14% [
7]. The national rate of HIV prevalence for Mexican adults is 0.3% [
3]. In addition, the majority of FSWs in Tijuana and Cd. Juarez are low-income and report entering sex work out of economic necessity to support their family [
8]. Thus, SAVA syndemic theory may provide a better understanding of the contextual factors that contribute to HIV risk among FSWs in the US-Mexico border region.
As suggested by Amaro over a decade ago [
9], several studies have examined intimate partner violence (IPV) and history of abuse in relation to heterosexual women’s HIV risk. Although an empirical understanding of the relationship between current experiences of violence and HIV infection is still emerging, Maman et al. [
10] reviewed several theories that may explain why violence victimization predisposes women to contracting HIV: (1) through forced or coercive sexual intercourse with an HIV-infected partner; (2) by limiting women’s ability to negotiate safe sexual behaviors; and (3) by establishing a pattern of sexual risk-taking among individuals assaulted in childhood and adolescence. More recently, studies have documented the association between IPV and HIV among heterosexual women in different international settings [
11,
12] and age groups [
13]. Specific risk behaviors associated with IPV include inconsistent condom use and increased likelihood of engaging in sex with an HIV-infected partner or an injection drug user (IDU) [
14].
Ethnographic studies have documented the prevalence of history of abuse (i.e., history of childhood abuse, IPV, and client-perpetrated violence) and of HIV infection among FSWs in various international settings [
15‐
17]. History of violence among FSWs has been associated with increased drug use and greater HIV vulnerability. For example, FSWs in India [
18] who reported abuse from clients and intimate partners were less likely to use condoms and were therefore at increased sexual risk for HIV. In a study of FSWs in Canada, increased violence by clients and sex and drug-related HIV risk behaviors were associated with sharing illicit drugs with clients [
16]. Surratt [
19] reported that among FSWs in the US Virgin Islands, those who used illicit drugs were significantly more likely to report unprotected sex, client violence, and STIs. FSWs in New York City who injected drugs in the past year and who were HIV-positive were more likely to report combined physical and sexual abuse from intimate and commercial sexual partners [
20]. Although these studies have identified specific HIV risk behaviors associated with histories of violence, few studies have focused on client-perpetrated violence specifically, and the causal links between violence and HIV-seropositivity have not been established.
Miller [
21] developed a theoretical model in an effort to understand the relationship between history of sexual abuse and HIV risk among women. This model includes many of the sequelae associated with history of abuse including substance abuse, psychopathology (e.g., depression and PTSD), and sexual dissatisfaction and dysfunction (e.g., an inability to sustain intimate relationships, and participation in sex work). Miller proposed three possible causal pathways in the relation between sexual abuse and engaging in HIV-risky behavior: psychopathology as a result of abuse; drug use to cope with the abuse experience; and sexual adjustment problems related to taking sexual risks (e.g. obsession with sexual activity, participation in self-destructive sexual relationships, and sex work). Based upon Miller’s model, this study examines injection drug use as a mediator of the relationship between client-perpetrated violence and HIV-seropositivity among FSWs.
The specific links between history of abuse and HIV-seropositivity may not be entirely clear and may not be unidirectional, but some research exists on the relationship between violence victimization and increased needle sharing among IDUs. In a multi-site study of female IDUs in the US, Wagner and colleagues [
22] found that IPV was associated with higher levels of syringe sharing. In a study of IDUs in Vancouver, Canada, 68% of women had a lifetime history of sexual violence, which was significantly associated with syringe sharing [
23]. A previous study with IDUs in the same city showed that lifetime experience of sexual abuse was independently associated with syringe sharing among male and female IDUs [
24]. However, these studies focused on lifetime experience of sexual violence, which could include either childhood or adulthood abuse, and results may not generalize to FSW populations currently experiencing abuse by clients. Therefore, further investigation of the relationship between recent client-perpetrated abuse, injection drug use, and HIV among FSWs is warranted.
This study utilized cross-sectional data to test injection drug use as a mediator of the relationship between client-perpetrated abuse and HIV-seropositivity among FSWs. We hypothesized that: (1) client-perpetrated abuse would be associated with HIV-seropositivity; (2) client-perpetrated abuse would be associated with injection drug use by FSWs; and (3) injection drug use would be associated with HIV-seropositivity. Mediation analysis allows for the examination of possible mechanisms through which independent variables affect dependent variables [
25]. We conducted a mediation analysis to examine injection drug use as a possible mechanism by which client-perpetrated abuse may affect HIV-serostatus, specifically examining whether injection drug use mediates the relationship between client-perpetrated abuse and HIV-seropositivity. Since only 3% (
n = 28) of FSW-IDUs in our sample reported sharing needles with their clients in the past 6 months, we chose to use injection drug use as the mediator instead of needle sharing.
Discussion
Consistent with previous studies of FSWs, the women in our sample reported frequent experience of client-perpetrated abuse. Moreover, FSW-IDUs were significantly more likely to experience client-perpetrated emotional, physical, and sexual abuse and be HIV-positive as compared to their non-IDU counterparts. Being an IDU may be a critical marker in identifying FSWs who are at increased risk for violence victimization and infection with HIV. Our results showed that client-perpetrated abuse was significantly associated with a higher prevalence of injection drug use among FSWs, and those who experienced client-perpetrated sexual abuse were more likely to be HIV-positive, highlighting the need to consider history of abuse and injection drug use when assessing HIV risk among FSWs in this region.
As hypothesized, injection drug use partially mediated the relationship between client-perpetrated sexual abuse and HIV-status, suggesting that injection drug use may account for a significant proportion of this relationship. FSWs who are victims of violence may engage in drug use in order to numb themselves from the psychological consequences of the abuse and fear of revictimization. Wechsberg et al. [
17] found that sex workers in South Africa with a history of abuse (childhood, IPV, and client-perpetrated) had a fear of future victimization and discomfort with the relationship dynamics with men, which in turn led to increased substance abuse and greater sexual risk. Additionally, FSWs may be more likely to acquiesce to requests for unsafe sex in order to earn more money to support their drug addiction [
30].
Although this study identified injection drug use and history of client-perpetrated violence as important correlates of HIV risk among Mexican FSWs, it is likely that there is an underlying complexity of risk factors such as mental health disorders associated with trauma, gendered power dynamics, poverty, and societal norms and practices that contribute to FSWs’ overall risk [
32‐
34]. Furthermore, these risks may be exacerbated by injection drug use. For example, a qualitative study among male and female IDUs in Tijuana and Cd. Juarez found that female IDUs often obtained and used drugs within the context of a sexual relationship with a drug-using, male romantic partner or spouse [
35]. This could contribute to women’s receptive needle sharing or being “second on the needle,” [
35,
36] which in turn may reflect a form of submission to their male partners [
37]. These observations suggest that research with FSW-IDUs and their drug and sexual partners should take into consideration relationship dynamics and the intertwined nature of their drug use with sexual partnerships. Further research is warranted examining multi-level (i.e., micro-, meso-, and macro-level) factors of risk among this population. HIV prevention research targeting both FSWs and clients is urgently needed in order to adequately account for the clients’ sexual and drug risk taking and to identify potentially overlapping networks of high-risk drug- and sex-related partners who can be targeted for HIV prevention and harm reduction efforts [
16,
38].
Although this study adds to the knowledge base on the relationship between client-perpetrated abuse, drug use, and HIV risk among FSWs, several limitations must be noted. First, because this study was cross-sectional, causal inferences cannot be drawn. Additional longitudinal studies that assess onset of abuse, injection drug use, and HIV-seropositivity may further clarify the observed associations. Second, the present study is retrospective and relies primarily on self-report data, which can entail recall bias. However, the recall period for the questions was relatively short (e.g., past 30 days to past 6 months), and previous research has provided validation for self-report data with IDU populations [
39‐
41]. A third limitation was the limited, fixed nature of the abuse items selected from the Addiction Severity Index. These items did not assess multiple experiences of abuse, extent of abuse, or the number of different abusers, and therefore it may not reflect the true experience of client-perpetrated abuse for some of the FSWs in our study. Last, the results of this study may not be generalizable to other ethnic groups of FSWs, nor even to other Latina FSW groups. The participants in this study constituted convenience samples from two US-Mexico border cities and may not be representative of FSWs in other cities or of FSWs in either of those cities as a whole, especially since the intervention study deliberately recruited high-risk FSWs.
Further understanding of the relationship between client-perpetrated violence, injection drug use by FSWs, and FSWs’ HIV-risk behavior is important for the development of treatment and prevention strategies that adequately address the complexity of risks that FSW-IDUs face. Future HIV prevention interventions serving FSWs in this region should include violence screening and prevention as well as treatment for mental disorders, in order to address any negative sequelae of trauma and to help FSWs avoid potentially violent clients. The results of this study also suggest the need to treat victimized FSWs’ injection drug use, their impairment due to drug use, or both, in order to reduce the effect of client-perpetrated abuse on the risk of acquiring HIV. Increased access to drug treatment services may greatly enhance HIV prevention for this population. For example, Amaro and colleagues [
42] found that treatment of drug addiction and trauma simultaneously was effective in reducing HIV sex-risk behaviors among poor inner-city Latina and African American women.
Finally, there is a need for HIV prevention interventions to move beyond exclusively individual-level approaches by including male clients in order to reduce women’s vulnerability to violence and HIV risks. A solely individual-level approach assumes that women can engage in preventive behaviors free from influence from their partners or larger societal norms [
33]. However, research indicates that women’s HIV risk behavior is influenced by partner violence and power relationships that impact their ability to negotiate sexual and drug risk reduction behaviors [
16‐
18,
22].
Acknowledgments
The authors respectfully acknowledge the participation of all the women in this study for making this work possible. We also thank the US-Mexico bi-national study staff, Brian Kelly and Sandra Volz for editorial assistance, and Dr. Willo Pequegnat at the National Institute of Mental Health for her support and encouragement. Funding for this research was provided through NIMH Grants R01 MH65849, R01 MH65849-Supp, and NIDA Grant R01 DA023877.