Introduction Differences in sexual networks likely explain the disparity in the scale of HIV epidemics in sub-Saharan Africa and India. HIV and sexually transmitted infection (STI) discordant couple studies provide insights into important aspects of these sexual networks. We wished to quantify the role of male sexual behaviour in HIV transmission in married couples.

Methods We analysed patterns of HIV, HSV-2 and syphilis sero-concordance and discordance in married couples from two community surveys in India: the National Family Health Study-3 for HIV-1 (a nationally representative household survey) and the Centre for Global Health Research health check-up for HSV-2 and syphilis. A statistical model was used to estimate the fraction of infections introduced by each of the two partners accounting for higher mortality and separation among HIV concordant couples.

Results Only 0.8%, 16.0% and 3.5% of couples were infected with HIV-1, HSV-2, and syphilis, respectively. A large proportion of infected couples were discordant (73.1%, 55.0% and 84.2% for HIV-1, HSV-2, and syphilis, respectively). Among couples with any STI, the male partner introduced the infection the majority of the time (HIV-1: 85%, HSV-2: 62%, syphilis: 75%).

Conclusions Male infidelity appears to be the driving force of the HIV/STI epidemic our study population and likely in the Indian population at large. Ensuring safe male client and female sex worker contacts should remain a primary target of the National AIDS Control Program in India.