In Rural South Africa, ART Reduces HIV Incidence Rate

Jim Kling

March 15, 2012

March 15, 2012 (Seattle, Washington) — Antiretroviral therapy (ART) can reduce HIV incidence, even when treatment begins in patients with CD4 cell counts below 200 cells/µL, according to research presented here at the 19th Conference on Retroviruses and Opportunistic Infections.

Although ART has been used for years to reduce transmission rates, there is no empirical evidence that it works, especially in settings with suboptimal care and high variations in treatment practice, according to Frank Tanser, PhD, associate professor of health and population studies at the University of KwaZulu-Natal in Durban, South Africa.

The researchers sought to determine whether treating HIV-infected people with ART reduces the risk for HIV transmission in the surrounding community in a hyperendemic African setting. The team analyzed longitudinal HIV and demographic surveillance data from the Africa Centre for Health and Population Studies.

For each year of the study (2004 to 2011), the researchers estimated the spatial variation in the proportion of HIV-positive adults receiving ART. They also followed 16,588 HIV-negative adults (15 years or older) and conducted a multivariable analysis to determine the effect of ART coverage on infection rates in the surrounding community.

There were 1395 HIV seroconversions during the 53,042 person-years of observation, for a crude HIV transmission rate of 2.63 per 100 person-years (95% confidence interval, 2.50 to 2.77). The team adjusted for sexual behavior, sociodemographic variables associated with HIV acquisition, and HIV prevalence in the surrounding community.

They found that an increase of 1.0% in ART coverage led to a 1.7% decline in the odds of HIV acquisition among adults living in the same community (P < .001).

The study did not take into account the impact of individuals having sexual partners in other towns. "It's likely an underestimate of the true reduction [in HIV incidence]," Dr. Tanser said at a press conference.

The study helps to pin down the cause of the decline in HIV transmission. "Once we really started treating HIV, the rates of new infections in Africa started to come down. But that could be attributable to a lot of things. It may already have been happening, or a lot of the early cases may have died," said Chris Beyrer, MD, MPH, MD, MPH, professor of epidemiology and international health at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, and the North American representative for the International AIDS Society.

The study is welcome news, but much work remains to be done. Dr. Beyrer noted that men have substantially lower CD34 cell counts at treatment initiation than women.

"If we're serious about treatment and taking control of this epidemic, we have to do better with men," Dr. Beyrer told Medscape Medical News.

Dr. Tanser and Dr. Beyrer have disclosed no relevant financial relationships.

19th Conference on Retroviruses and Opportunistic Infections (CROI): Abstract 136LB. Presented March 8, 2012.

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