In the first good news on India's battle with HIV/AIDS, a new Indo-Canadian study has pronounced a remarkable one-third decline in new HIV infections in the worst-hit regions of the country.

In the southern states of Tamil Nadu, Andhra Pradesh and Karnataka, considered the 'epicentre' of the disease, the prevalence of HIV-1 (the most common variant of the virus in India) fell from 1.7 per cent to 1.1 per cent - a relative reduction of 36 per cent. Similarly, a one-third decline in new cases has been found in Maharashtra, another high-vulnerability state.

The study, 'Trends in HIV-1 in Young Adults in South India from 2000 to 2004: A Prevalence Study', appeared in the April 8, 2006 issue of the British medical journal, 'The Lancet'. It investigated the prevalence of HIV-1 in young people attending antenatal and STI (sexually transmitted infections) clinics in four southern states and 14 northern states in India. This study is also the largest-ever examination yet of antenatal clinic attendees.

It used data from 300,000 women aged 15-24 and 60,000 men aged 20-29. The investigators found that HIV-1 prevalence among women in the south fell from 1.7 per cent to 1.1 per cent from 2000 to 2004, while for men attending STI clinics in the south, there was an reduction of 7.6 per cent in HIV-1 prevalence.

A collaboration between the University of Toronto (Canada) and the Postgraduate Institute of Medical Education and Research (PIMER) in Chandigarh (India), the study clearly indicates that the country's HIV/AIDS control programme - with its thrust on condom use and awareness initiatives - is finally making headway. It could well silence detractors and pessimists about India's HIV/AIDS epidemic.
"There have been many predictions, mostly based on guesswork, that India's HIV problem will explode, as it did in southern Africa; but we now have direct evidence of something positive," says the study's co-author Professor Prabhat Jha of the University of Toronto. "The good news is that HIV in young adults appears to be declining in south India - most likely, or perhaps only, due to males visiting sex workers less or using condoms more." Lead author Dr Rajesh Kumar of PIMER says that the fall in the south was seen in both rural and urban areas.

The study examined alternative explanations as well, but concluded that changes in testing or in deaths from AIDS do not appear to explain the decline. "The first question we ask as scientists is if our findings are real; it appears they are," says Jha.

"HIV growth in the country has been predicted at up to 9 per cent of the population being infected, but these predictions are mostly based on opinions and guesswork," adds Kumar. "The incidence of new infections in young people is the best measure of where the epidemic is going and we feel the most reliable data comes from antenatal and STI clinics."

Jha, however, sounds a note of caution regarding states in north India, saying that trends there remain uncertain and poorly studied due to little data being available. Though HIV-1 prevalence in the north is only about a fifth of that seen in the south, the north had a lower coverage of sites than the south.

"Most of the 478 clinics in the north did not have antenatal or STI clinics and peer interventions are limited," says Kumar. Though it is early days yet, he warns that it is only a matter of time before increases occur in this region. "The north is not immune; complacency is dangerous. There is rapid need to scale up prevention in hot spots and expand surveillance and testing." Jha explains further: "Such strategies are partly in place in the south, but must be extended to high coverage in each southern district. Equally important, sex worker interventions must be replicated in the north."

The study has not covered India's north-eastern states because, says Kumar, states like Manipur are facing an HIV epidemic due to transmission via intravenous drug use rather than through the sexual route, and thus require a different module for analysis.

The scientists, who were in the capital to release the study findings in March 2006, aver that young people, especially young women who have recently married, are a good group to study HIV prevalence. India, like most developing countries, uses unlinked anonymous HIV-1 testing of pregnant women attending antenatal clinics to monitor trends in the general population.

In India, more than 91 per cent of women live with their husbands by the age of 25. They should thus represent a reliable group to monitor changes in HIV-1 incidence even though this is not necessarily the way to accurately predict HIV-1 prevalence in the general population, says Kumar. "Most women in our study reported only husbands as the sexual partner. We concluded from this that most new infections thus come from male use of female sex workers," he adds.
According to data from the government's National AIDS Control Organization (NACO), about 5.13 million people aged 15-49 years were infected with HIV-1 in 2005. The true prevalence, however, is disputed because even small changes in prevalence could translate to large absolute numbers of infected individuals. Heterosexual contact is responsible for about 85 per cent of all new HIV-1 infections in India and about 75 per cent of HIV-1 cases reside in the southern states of Andhra Pradesh, Karnataka and Tamil Nadu and the state of Maharashtra, which constitute 30 per cent of the country's population.

"What matters more than the number of HIV+ cases is where the epidemic is going? We need to stop new infections rather than get into debates about figures and numbers," stresses Kumar.

The study recommends that enhancing routine surveillance - including more questions on risk factors, pregnancy, history, husband's history and additional STI testing via antenatal clinics and other sites - is a powerful and cost-effective way to monitor the growth of India's large and heterogenous HIV epidemic.

"We need to understand the sexual networks and transmission patterns in India. While the heterosexual network is the strongest, we need more information on men having sex with men (MSM) and male sex workers (MSWs)," points out Jha. "We recommend that interventions be intensified not only on female sex workers and their clients but also on other high-vulnerability groups like MSM and MSWs."
Kumar cautions that while the findings are good news, the battle is far from over. "HIV remains a huge problem in India and we have to remain vigilant," he says. "We're not saying the epidemic is under control yet - we are saying that prevention efforts with high-vulnerability groups thus far seem to be having an effect."