Behavioral Intervention to Reduce Sexual and Injection Risks Among Female Sex Workers Who Also Inject Drugs in Mexico

The investigators propose a highly efficient four-arm (factorial) trial to simultaneously test the efficacy of two behavioral interventions aimed at:

* increasing condom use in the context of ongoing drug use and
* decreasing needle and paraphernalia sharing

among female sex workers who also inject drugs in two Mexican-U.S. border cities: Tijuana and Ciudad Juarez.

Our specific aims are:

* Aim 1: To evaluate the efficacy of a behavioral intervention to decrease sharing of syringes and injection paraphernalia among FSW-IDUs. We hypothesize that FSW-IDUs in the active experimental injection risk reduction condition will report: (a) less receptive and distributive needle sharing; (b) less sharing of injection paraphernalia; (c) obtaining syringes and injection paraphernalia from safer sources.
* Aim 2: To evaluate the efficacy of a behavioral intervention to increase condom use among FSW-IDUs in the context of ongoing drug use. We hypothesize that FSW-IDUs in the active experimental sexual risk reduction condition will: (a) report less unprotected vaginal and anal sex; and (b) have fewer incident cases of specific STIs.
* Aim 3: To evaluate the joint effects of these two behavioral interventions to increase condom use and reduce sharing of needles and syringes/injection paraphernalia among FSW-IDUs. We hypothesize that the joint effect of these interventions will generate greater risk reductions compared to either intervention alone.
* Aim 4: To determine the extent to which theoretically-important components of our interventions (i.e., self-efficacy, outcome expectancies, attitudes, intentions) represent underlying mechanisms of change in primary outcomes (i.e., sexual- and injection-related risk reductions).
* Aim 5: To explore subgroup differences in the efficacy of: a) the sexual risk reduction, and b) the injection risk reduction intervention based on background characteristics, contextual factors, social factors and intrapersonal factors.

Eligibility Criteria:
Inclusion Criteria:

* be biologically female
* be at least 18 years old
* report having exchanged sex for money, goods or drugs within the last month
* report having injected drugs within the last month
* report having unprotected vaginal or anal sex at least once in last 30 days
* report sharing needles/syringes or other injection paraphernalia (i.e., cottons, cookers, water) at least once in the last month
* live in Tijuana, Ciudad Juarez or its suburbs, as determined through municipal boundaries in each city
* test HIV-negative at baseline
* agree to receive antibiotic treatment for chlamydia, gonorrhea, syphilis trichomonas vaginalis or bacterial vaginosis if they test positive at baseline.

Exclusion Criteria:

If women report:

* consistent use of condoms for vaginal and anal sex with all male partners during the previous month
* not being able to provide verification of injection drug use (i.e. track marks)
* not sharing needles/syringes or paraphernalia at least once in the last month
* being under 18 years of age
* being male or transgender
* being incapable of giving informed consent
* planning to permanently move outside of the municipal boundaries of Tijuana or Ciudad Juarez within the next year.