HIV risk and the overlap of injecting drug use and high-risk sexual behaviours among men who have sex with men in Zanzibar (Unguja), Tanzania.

Background: Men who have sex with men and inject drugs (MSM-IDU) are particularly vulnerable to HIV infection and have the potential to transmit HIV across multiple populations through their male and female sexual partners and injection drug-using partners.

Methods: Respondent-driven sampling was used to recruit men who reported engaging in anal sex with another man in the past 3 months, aged ≥15 years, and living in Unguja, Zanzibar. Participants responded to a face-to-face interview about their HIV and injecting risk behaviours and were tested for HIV, Hepatitis B (HBV) and C (HCV) and syphilis.

Results: Among the 509 MSM who enrolled in the survey, 14% (n=66) reported injecting drugs in the past 3 months among which 66% used heroin, 60% used a needle after someone else had and 68% passed a needle to someone else after using it. MSM-IDU were significantly more likely to have two or more non-paying male receptive sex partners and to have engaged in group sex in the past month, to have symptoms of a sexually transmitted infection in past 6 months, to have been arrested or beaten in the past 12 months and to be infected with HIV and co-infected with HIV and HCV compared to MSM who did not inject drugs. MSM-IDU were less likely to have used a condom at last sex with a non-paid female partner, to know where to get a confidential HIV test and to have ever been tested for HIV compared to MSM who did not inject drugs.

Conclusions: MSM-IDU, and MSM in general, in Unguja practice multiple high-risk behaviours that put them at risk for blood-borne and sexual transmission of HIV and HCV infection. Targeted interventions for MSM-IDU must account for the overlap of high-risk sexual and drug-using networks and integrate injection drug use and HIV services.