When the United Nations presented their 2009 Progress Report on HIV/AIDS in late September, there was good news. Over a million people in the developing world began treatment with antiretroviral drugs (ARVs) last year. Tremendous strides have been made in preventing mother-to-child transmission of HIV. Yet the news was tempered by the fact that 2.7 million people became newly infected in 2007, the last year for which estimates exist. Preventing new adult infections has been a losing battle in Africa and elsewhere.
Only by preventing new infections in sexually active teenagers and adults will we begin to see a true end to the AIDS epidemic. The Mochudi Project is designed to address exactly this problem.
Mochudi, a village of about 40,000 people in southern Botswana, is the site of a new research project by the Harvard AIDS Initiative. The village has an adult HIV prevalence of 25%. The Mochudi Project will take a comprehensive, community-based approach to HIV prevention. It combines established prevention methods, along with several innovative methods that will be tested for the first time.
Treating Acute Infection
The Project will emphasize the detection and treatment of acute (recent) HIV infections. When a person is infected with HIV, his or her viral load (the amount of HIV virus in the body) climbs steeply in the first weeks of infection. In the usual course of HIV infection, the body’s immune system brings the viral load under control after several weeks or months, dramatically reducing the level of HIV for a number of years. When viral load drops, the risk of transmission also drops. Yet until this happens, a person with acute infection is more likely to infect others, especially if he or she is involved in more than one relationship.
An added concern is that about 25% of people infected with HIV-1C, the virus of southern Africa, seem to have high viral loads that are prolonged for up to one or two years after infection, much longer than others. This subset of highly infectious people may be responsible for the majority of transmissions, making them an important group to reach with prevention programs. This is a hypothesis that researchers will test.
By identifying men and women recently infected with HIV and starting them on antiretroviral treatment to reduce their viral load, we hope to prevent new adult infections. This “test and treat” strategy is similar in principle to the successful strategy of giving pregnant women ARVs to prevent them from passing the virus to their infants. By targeting therapy to the most infectious individuals, we hope to significantly reduce the rate of new infections in the village.
Contact Tracing and Viral Sequencing
We will also use new tools in genetics to map how HIV spreads within a community. By comparing viral genetic sequences of new infections, we will be able to tell how closely related they are to each other. Comparing viral sequences will help us investigate the tendency of people with new infections to group together in what is known as a Transmission Cluster. In effect, we will be able to draw an anonymous map of how HIV actually spreads within a village. This information will be crucial in helping to adapt prevention efforts to what is actually happening in Mochudi.
Using What Works
Though the Project will evaluate several promising new strategies for HIV prevention, it also incorporates interventions already in use, including Voluntary Counseling and Testing (VCT), condom use, male circumcision, and education about risk reduction with respect to number of sexual partners. Recent studies about the effect of circumcision have been promising. Three randomized trials in sub-Saharan Africa designed to measure the impact of male circumcision on HIV infection among heterosexual men showed a strong protective effect, with about a 60% reduction in the risk of infection.
Another important component of the Mochudi Project is to quantify the effectiveness of several different prevention methods being used at the same time. To accomplish this, mathematical models will be developed to identify synergies among prevention methods. Evaluation of the cost-effectiveness of combined methods will also be performed.
Ambitious in scope, the Mochudi Project combines the best of what we already know about HIV/AIDS prevention with promising new methods. The ultimate goal of the Project is to evaluate prevention interventions that could be scaled up for Botswana and southern Africa. The more local goal is to slow and eventually stop the spread of HIV/AIDS in one village in Botswana.
The Mochudi Project has received initial funding from the National Institutes of Health (NIH) to demonstrate the feasibility and acceptability of the program. We are seeking additional funding to carry the program through to completion.