Summaries
Track C: Epidemiology and Prevention

Meanwhile, the Asian epidemic, or should we say epidemics, as the diversity of its path in this region is its only predictable characteristic, continues to unfold. Thailand and Cambodia stand out as countries that experienced prevalence levels that were high for this part of the world, but responded in a comprehensive and pragmatic manner, at least in relation to the promotion of condoms in the context of commercial sex. We should not pretend that the Asian epidemic on a per capita basis is likely to ever approach what we have seen in Africa, but there are many people in Asia at risk, and plausible mathematical models predict a slow and steady increase in infection rates if current levels of risk behaviour remain unchanges.

Risk of transmission through injecting drug use and male to male sex are other behaviours that are recognised in the Asian region as being associated with the increased potential for transmission. These behaviours, like commercial sex, remain stigmatised and a number of the governments of the region have not been able to implement large-scale, evidence based prevention strategies, including sex education, condom availability, provision of clean injecting equipment and diagnosis and treatment of sexually transmissible infections. Leadership is the key to unlocking the resources and political will to move forward in these areas.

Prevention itself stands the risk of marginalisation, if not yet stigmatisation, in the global HIV response. The justified excitement to expand access to the new and effective treatments has made prevention look like a strategy from other times, even though we know that treatment is not a cure, and it will be many years before even today's best treatment practice is available universally in developing countries.

So a continued focus on what works in prevention, recognising that communities will have different ways of implementing the same strategy, must remain a central pillar in the HIV response. Furthermore, it can not be compromised by ideological debates about the morality of prevention, when the alternative is the clearly immoral outcome of needlessly exposing people to a life threatening disease. As one participant in a conference debate put it "condoms work, needles save lives, and negotiation empowers"


TUESDAY
13 July

As the conference moved into its second day, prevention themes moved from the global and political, to more specific discussions of locally-based strategies and their effectiveness.

Two sessions focussed on interventions to reduce HIV risk among injecting drug users. The practice of drug injecting has long been recognised as representing a high risk of HIV transmission if clean injecting equipment is not available. The principles of harm reduction, though proven to be highly effective in preventing HIV transmission, are yet to be widely implemented in many countries, both in the industrialised and developing world, but there are signs that their acceptance is growing. A striking report from border of China and Vietnam, two countries not previously recognised for implementing harm reduction, showed that the distribution of clean needles and syringes, and community education on the drug-related harm were broadly acceptable across key community sectors including the police. Although it is too early to tell whether HIV incidence will fall substantially as a result of these measures, it has remained stable on both sides of the border since the project began.

Other reports on injecting drug use showed that injecting related risk of HIV is at high levels in a number of developing countries, and that significant political and social barriers still stand in the way of evidence-based prevention strategies.

The sex industry, both buyers and sellers, was the subject of another session. Studies from China (in women) and Canada (in gay and bisexual men) reported on the taxonomy of sex work. There are clearly defined subgroups of people engaged in sex work, and it is possible to distinguish different patterns of risk between the groups, with clear implications for prevention strategies.

Another session presented disturbing results on the impact of the HIV epidemic in young people in southern Africa. Studies from both Zimbabwe and South Africa showed that family breakdown was associated with higher levels of HIV risk in children. Thus the epidemic has a transgenerational effect both directly vertical transmission of the virus, and indirectly through the heightened exposure of children from affected families.

Access to testing has emerged as a key bottle neck for both prevention and treatment. In a number of countries, innovative approaches to increasing the uptake and acceptability of testing are being trialled. Some options considered were reducing time to receipt of results, tailoring access times procedures to client needs, and recruitment of couples.

For years now we have seen systematic documentation of the benefits of antiretroviral therepy in industrialised countries, and we are now, gratifyingly, starting to see similar results from developing countries. Reports from Uganda, Brazil and Hong Kong in a session on treatment outcomes demonstrated major gains in survival following the use of antiretroviral therapy. On the other hand, and disturbingly, people with HIV infection in the US are still more likely to miss out on early detection and adequate treatment if they are young, heterosexual or Black or Hispanic.


WEDNESDAY
14 July

The Epidemiology and Prevention track today focussed on men who have sex with men, and prisons, with two sessions on each topic. There was also a session that reported on the evaluation of media-based prevention strategies.

The issue of HIV risk and prevention among men who have sex with men is now well and truly on the agenda in a number of developing countries. Surveys and longitudinal cohort studies were reported today from Asia and Latin America. The reported prevalence of HIV infection ranged from 3% (China) to 17% (Thailand). Some studies also identified low levels of condom use, and high levels of bacterial sexually transmissible infections, although knowledge levels tended to be quite good.

Several studies focussed on estimating the incidence of HIV infection in men who have sex with men, whether by repeat testing in cohorts, or the use of sensitive-less sensitive (SLS) serological tests in cross-sectional samples. Overall incidence levels of 6% were found using the SLS test in a US study, with rates of over 20% in African-American men. Incidence was found to be at a similar level in a cohort of men in Buenos Aires. In the UK, the SLS approach was used, and detected incidence that was much lower than in the the US or Argentina, but increased to 3.5% in 2002.

Risk behaviour among HIV positive men have sex with men in Amsterdam found that a more favourable viral load result predicted increased risk behavior, and the UK study detected no evidence for a decrease in HIV incidence in the era of effective therapy. The prevention challenge is clear.

The risk of HIV in prison has similarly not been the subject of intensive investigation by prevention researchers in developing countries. The triple stigmatisation of incarceration, drug injecting and HIV or hepatitis C infection have all but guaranteed a low priority to programming in this area. Studies were reported today from Thailand, Indonesia, Pakistan, Iran and several Eastern European countries. They emphased the need for a high degree of cooperation between health and corrections authorities, to provide adequate prevention and treatmetn services to people in prison, thereby reducing the risks of HIV infection and tuberculosis. In some countries, NGOs have been allowed to work in prisons, and permitted to establish prevention programs that include education and even harm reduction strategies.

Despite these encouraging developments in several countries that might not have been expected to be in the forefront of prevention in custodial settings, prisons in many coutries remain a place where people are not likely to gain access to the means of either prevention or treatment for HIV or other bloodborne viral infections.

A group of reports from southern Africa and Cambodia described broadcast programs aimed at delivering prevention messages via the mass media, and some innovative techniques to address the challenge of evaluating outcomes. In addition to the more traditional information campaigns, drama series on both television and radio are being used to convey key messages about prevention by incorporating them into characterisation and story line. Evaluation by repeat surveys of various kinds showed that the information was getting across, and there were some indicators to suggest that behavior change had followed.


THURSDAY
15 July

Track C built to a crescendo today with a full plenary devoted to prevention, 8 abstract driven sessions, and two symposia. These sessions went some way towards restoring the balance in the program dominated by expanded treatment access.

The plenary session introduced several big themes of prevention. Over the past few years the groundwork has been laid for large scale trials of a number of prevention strategies. Trials are now underway, or close to implementation of the diaphragm, vaginal microbides, vaccines, male circumcision and treatment of HSV-2 as HIV preventive strategies. Although it will be several years before the first results are known there is a renewed mood of optimism that one or more of these strategies will be able to have a real impact on HIV transmission globally.

A lively session on molecular epidemiology showed that HIV is continuing to diversify in different parts of the world, through recombinant subtypes. Epidemic pathways of transmission could also be tracked in various places, using subtyping.

Behavioural risk came under scrutiny in a session devoted to so-called bridge populations, which are made up of people who have the potential to transmit infection in more than one way, eg via injecting drug use and sex, or to both male and female partners. There is a growing realisation of the complexity of risk networks in both the industrial and developing world, with clear implications for prevention strategies.

Although it will be years before the large scale effectiveness trials of female controlled prevention methods are available, information is emerging from smaller scale trials of safety and acceptability. In a session devoted to this area, results were presented on the first trial of a microbide formulated using an antiretroviral agent.

A session on sexually transmissible infections showed that HSV-2 is increasingly seen as playing a primary role in HIV transmission, with its high prevalence, lack of cure and strong association with HIV transmission risk in several studies.

An emerging nexus between treatment and prevention arises in the context of people newly diagnosed with HIV infection, or undertaking treatment. In a session on positive prevention, cross-sectional studies in Africa showed that treatment was not associated with increased risk behaviour.

The measurement of HIV incidence, the subject of another session, is seen as a key goal of surveillance. Direct measurement of seroconversion in cohorts, specialised assays for new infection and mathematical modelling all provide insight into incidence, but have various limitations as surveillance tools.

A session on vaccine trials revealed a contemplative state among researchers in this area, following the unsuccessful conclusion of the first Phase III trial. On the other hand, the state of knowledge in mother to child prevention has advanced to a stage where most countries should be able to achieve minimal transmission rates (2% or less) with limited resources.