UC San Diego

Background : Concurrent (overlapping) sexual partnerships potentiate transmission of HIV and other sexually transmitted infections (STIs), yet patterns of concurrency among female sex workers (FSWs) and high risk couples in the U.S.-Mexico border region remain poorly described. Aims : The aims of this dissertation were to : (1) qualitatively characterize relationship dynamics and behavioral norms within FSWs' different types of concurrent commercial relationships; (2) determine the prevalence and correlates of concurrency among FSWs and their intimate male partners; and (3) assess acceptability of pre-exposure prophylaxis (PrEP) including microbicides among these dyads. Methods : Chapter 2 describes the prospective, social-epidemiological study of HIV/STIs among FSWs and their intimate male partners in Tijuana and Ciudad Juárez, Mexico that this dissertation was nested within. Chapter 3 used in-depth interviews to explore relationship dynamics within FSWs' concurrent commercial relationships. Chapter 4 used questionnaires to determine the prevalence and correlates of concurrency among FSW- intimate partner dyads. Chapter 5 employed an iterative mixed methods approach to assess microbicide acceptability among these dyads. Results : Chapter 2 describes methods to recruit, screen and enroll 214 high risk couples (n=428) and provides recommendations for couple-based research. In Chapter 3, FSWs (n=46) described a range of commercial relationship dynamics and how the development of longer-term relationships with more lucrative clients rendered condom negotiation increasingly difficult. Chapter 4 found that, among 214 couples (n=428), 16% reported past-year steady (recurring) concurrency, which was associated with FSWs' income, men's caballerismo (positive form of traditional masculinity), and men's belief that steady partners had HIV/STIs. Chapter 5 found that microbicide interest was high among 185 couples (n=370), but couples had concerns about male partners' potential anger and implications of mistrust/infidelity (n=56). Conclusions : As a first examination of sexual partner concurrency among high risk FSW-intimate partner dyads, these findings carry important implications for couple-based HIV/STI prevention programs. Since condom use becomes increasing difficult as relationships become closer, additional HIV/STI prevention modalities may be needed. However, the ultimate effectiveness of PrEP will depend on product adherence, requiring couple-based interventions that promote risk communication and carefully involve male partners