Researchers root for ARVs

"We have seen substantial evidence that antiretroviral therapy is likely to prevent sexual transmission of HIV," said Salim Abdool Karim, M.D., director of the Center for the AIDS Program of Research in South Africa and vice chancellor for research at the University of KwaZulu-Natal in Durban.
Dr. Karim said that focusing on treatment of sexually active individuals will impact prevention because sexual transmission of HIV accounts for 87 per cent of the 39.4 million people living with HIV/AIDS.
Of the 4.9 million new infections of HIV last year in the world, 86 per cent were the result of sexual transmission.
Of the 3.1 million estimated deaths last year due to HIV, 88 per cent of the people acquired HIV through sexual transmission.
Policy makers and academicians need to stop looking at prevention and treatment as two different issues and appreciate the synergy between the programs, he said during a plenary address at the conference on HIV Pathogenesis and Treatment.
Introduction of antiretroviral therapy in resource-limited settings affects HIV prevention in several important ways, he said.
First, at the biological level, antiretroviral treatment reduces viral load in bodily fluids, making people living with HIV less likely to pass on their infection.
Additionally, use of antiretroviral treatment in the setting of post-exposure prophylaxis has significantly reduced infection due to needle-stick injuries, averting 81per cent of HIV infections in one needle-stick study, he said.
Likewise, he said, a case control study reported that prophylaxis following sexual exposure to HIV-infected individuals resulted in nine seroconversions out of 1,300 cases.
And importantly, he added, treatment of pregnant women with antiretrovirals has substantially reduced the risk of transmission of the virus to children.
Second, on the behavioral level, the availability of antiretrovirals encourages individuals to come forward for voluntary counseling and testing.
As evidence of this claim, he said that "at times the demand for testing that occurs after the introduction of treatment outpaces the ability to do the testing." It appears, he said, that the simple creation of treatment options gives individuals motivation to find out their status.
Finally on a systems or operational level, treatment delivery is likely to lead to overall improvements in health infrastructure and better integration of AIDS care with reproductive health and tuberculosis services, Dr. Karim said.
Using computer simulations to predict the impact of stand-alone treatment or prevention programs, versus a combined treatment-prevention strategy, he demonstrated the potential for dramatic declines in HIV infection and HIV-related deaths.
Using a prevention-only model, the best-case scenario would be the prevention of 1.5 million HIV infections with a concomitant reduction in mortality of 500,000 deaths.
But when the model was adjusted to reflect the impact of a combined treatment-prevention strategy, an estimated 2.5 million infections and 2.75 million deaths were averted.
"Expanding the number of prevention options and improving the delivery of existing interventions are top priorities in the global response to AIDS," said Helene Gayle, M.D., president of the International AIDS Society and director for HIV, TB and Reproductive Health at the Bill & Melinda Gates Foundation in Seattle.
"As access to HIV treatment grows, we are beginning to see important benefits for prevention," said Craig McClure, the IAS Executive Director. "We need to capitalize on this synergy."
The success and sustainability of AIDS treatment will depend on the global impact of antiretroviral therapy," Dr. Karim said, "not only on AIDS morbidity and mortality, but also on its impact on the prevention of new HIV infections."
While much of the evidence shows that treatment favorably impacts prevention, he said prospective clinical trials -- several of which are in progress -- are still needed to prove that impact.
"Even in the absence of trial data," Dr. Karim said, "the evidence for integrated prevention and treatment is compelling. For global control of the HIV epidemic, AIDS treatment must be accompanied by successful prevention."
And finally, Dr. Karim cautioned that even with significant reductions in viral loads, transmission to others is still possible so clinicians must continue to champion the need for safe sex practices.