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BOSTON. A once-promising experiment to see if treating genital herpes with a common drug could dramatically reduce susceptibility to HIV infection has found no protection whatsoever.
The finding, part of a long-awaited study released Monday at the 15th annual Retrovirus conference, was a setback for researchers hoping to find a pill that would slow the spread of the AIDS epidemic.
Nearly 20 years of various studies on herpes had shown that herpes infection nearly tripled the risk of contracting HIV.
The assumption was simple: Use acyclovir, a proven anti-herpes drug, to knock down that infection, and the odds of avoiding HIV would dramatically improve — by at least 50 percent, on par with the prevention benefit now attributed to male circumcision.
But when statisticians tabulated their data, the answer was certain: Those who took acyclovir to suppress their herpes infections acquired HIV infections at exactly the same rate as those who took a placebo.
One theory offered as to why the treatment did not work is that suppressing herpes is not enough. Although acyclovir is a very effective treatment for herpes simplex 2, it does not eradicate it, and many of those who take it will continue to have occasional flareups of genital ulcers.
Kevin DeCock, director of the Department of HIV/AIDS at the World Health Organization, said he was disappointed but not entirely surprised by the results of the study.
“What we really need,” he said, “is a herpes vaccine.”
In another study, researchers found that incidences of transmitting the AIDS virus to babies from infected mothers can be significantly reduced by extending antiretroviral drugs for periods up to six months.
The treatment regimen has been limited to giving antiretroviral drugs to the mother in labor and child at birth. That reduced the risk of transmitting the virus to the baby, yet many babies born uninfected went on to acquire HIV in the lengthy period of breast-feeding because of contamination of the mother’s milk.
“Making breast feeding safe is an urgent need,” said Taha Taha, a researcher from Johns Hopkins who led a study in Malawi.
Breast feeding accounts for up to 48 percent of HIV infections among infants in developing countries, researchers said.
The findings open the way for new prevention strategies in areas where infected mothers cannot avoid breast-feeding for many reasons. They include lack of access to formula, strong cultural traditions of breast-feeding and reluctance to use formula for fear of being stigmatizedas being infected.
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