Background: HIV incidence and prevalence have been reported to be declining in India, especially in the southern state of Tamil Nadu. This decline primarily reflects trends in heterosexual populations, the main focus of national prevention programs. Data on other risk groups in India, including men who have sex with men (MSM), are sparse. MSM are particularly difficult to access and remain a hidden population partly because anal intercourse (AI) is a crime punishable by Indian law and sociocultural pressures lead many MSM to marry so they are having sex with men and women (MSMW). We characterize HIV and sexually transmitted infection (STI) prevalence and risk behaviors among MSM and MSMW in Tamil Nadu.

Methods:  Participants were eligible if they were at least 18 years old, self-identified as male, and had had anal or oral intercourse with a man in the prior year. Respondent-driven recruitment was used to recruit 721 participants between October 2008 and November 2008 across 19 towns in Tamil Nadu. Behavioral data and blood samples were collected. All samples were tested for HIV (double ELISA), hepatitis B virus (HBV) infection (HBsAg), herpes simplex-2 virus (HSV-2) infection (IgG ELISA), and syphilis (RPR and TPPA). Logistic regression was used to identify factors independently associated with HIV infection.

Results:  Median age was 28 years (IQR 23 to 36); 34% were married and 56% single; 60% self-identified as bisexual and 40% as homosexual. Median number of male partners in the prior year was 15 (IQR 6 to 50); HIV⁺ persons reported significantly more partners (p <0.001). All participants reported unprotected anal intercourse (UAI) with at least 1 partner in the prior year; 24% reported UAI with all partners. Prevalence of HIV, HSV-2, HBV, and syphilis were 9%, 26%, 2%, and 8%, respectively; among married men, all were higher:  14%, 32%, 3%, and 11%, respectively (p <0.05 for HIV and HSV-2). Concurrent HSV-2 seropositivity and number of partners in the prior year were associated with prevalent HIV infection in the multivariate model.

Conclusions:  We observed a high prevalence of HIV/STI among MSM especially MSMW, who are of particular concern because they serve as a bridge population to their likely monogamous housewives potentially negating some of the positive impact of prevention programs in India. Further, the high prevalence of STI and the fact that UAI was universal constitute “the perfect storm” for an explosive HIV epidemic among MSM and MSMW. Preventive measures are urgently needed in this marginalized population.