Background:  Recent studies suggest that MSM have higher HIV prevalence than other African men, however the interactions between epidemics in MSM and heterosexual populations are poorly understood. Behavioral studies suggest that African MSM often have sex with women and indicate the potential for bridging transmission. Prior studies document an HIV prevalence of 21% amongst MSM sex workers (MSM-SW) in Mombasa, and indicate that sex with women occurs. Our study aimed to describe female partnerships of MSM-SW in Mombasa, and to explore risk factors for unprotected sex between women and MSM-SW.

Methods:  MSM-SW recruited from existing high-risk and HIV⁺ cohorts in Mombasa completed intake questionnaires and prospective behavior diaries. Participants self-recorded details of each sexual encounter and each sexual partner for 6 weeks and also provided details of their 3 most recent partnerships. Proportions were compared using χ² tests.

Results:  In the study, 83 MSM-SW recorded 1014 partners. Of the 215 (17%) female partners, 51% (109) were aged 18 to 29 years, 79% were of African, 13% Arabic, and a minority Caucasian or Indian ethnicity (4% & 3%). The majority of women, 92% (198), were Kenyan, of whom 80% (159) were Mombasa residents. Of 43 recent female partners, 35 (81%) were unmarried, and of 8 (19%) married women, 3 were spouses of MSM-SW. One-hundred-forty-four women (67%) paid an MSM-SW for sex, while 39 women (18%) were paid by an MSM-SW. Paying clients made up 99 (72%) of 138 single episode sexual contacts and 45 (58%) of 77 of recurring relationships. Of 96 new transactional contacts, 36 (38%) met on the street or beach, and 31 (32%) met in bars or nightclubs; 15% (32) of all partnerships were non-transactional and 35% (9/26) of regular partnerships. The majority of sexual encounters, 99% (212), between women and MSM-SW included penetrative sex: vaginal sex (VI) 87% (186), anal sex (AI) 54% (117) and both acts 43% (91). Of the sexual acts, 38% (70) of vaginal sex and 46% (54) of anal sex were unprotected. Unprotected sex (VI or AI) was associated with sex with a regular MSM-SW partner (62%, OR = 2.8, P =0.018 vs 36% acts in single encounters), and non-transactional sex (63%, OR = 2.7 vs acts paid for by female partner 38%, P =0.041).

Conclusions:  Although most sex partners of MSM-SW are men, sex with local women is also common, usually transactional and often unprotected. Little is known of the personal risk awareness and motivations for women seeking sex with MSM-SW, however these issues risk being overlooked by interventions targeting risk reduction between MSM alone.