Background: Major increases in HIV-1 prevalence in India have been predicted. Incident infections need to be tracked to understand the epidemic's course, especially in some southern states of India where the epidemic is more advanced. To estimate incidence, we investigated the prevalence of HIV-1 in young people attending antenatal and sexually transmitted infection (STI) clinics in India.
Methods: We analysed unlinked, anonymous HIV-1 prevalence data from 294 050 women attending 216 antenatal clinics and 58 790 men attending 132 STI clinics in 2000-04. Southern and northern states were analysed separately.
Findings: The age-standardised HIV-1 prevalence in women aged 15-24 years in southern states fell from 1.7% to 1.1% in 2000-04 (relative reduction 35%; p(trend)<0.0001, yearly reduction 11%), but did not fall significantly in women aged 25-34 years. Reductions in women aged 15-24 years were seen in key demographic groups and were similar in sites tested continuously or in all sites. Prevalence in the north was about a fifth of that in the south, with no significant decreases (or increases) in 2000-04. Prevalence fell in men aged 20-29 years attending STI clinics in the south (p(trend)<0.0001), including those with ulcerative STIs (p(trend)=0.0008), but reductions were more modest in their northern counterparts.
Interpretation: A reduction of more than a third in HIV-1 prevalence in 2000-04 in young women in south India seems realistic, and is not easily attributable to bias or to mortality. This fall is probably due to rising condom use by men and female sex workers in south India, and thus reduced transmission to wives. Expansion of peer-based condom and education programmes for sex workers remains a top priority to control HIV-1 in India.