Study: Pill thwarts spread of genital herpes

By Julia Sommerfeld
Seattle Times staff reporter

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Genital herpes is a silent but stubborn epidemic. The sexually transmitted virus infects an estimated one in five Americans over age 12, according to the U.S. Centers for Disease Control and Prevention. As many as 90 percent of those who have it don't know it because most people with the virus have mild or no symptoms.

It's a serious public-health issue because the disease is incurable, and herpes sores on the genitals can be painful and facilitate the transmission of HIV.

The finding published in today's New England Journal of Medicine showed the drug valacyclovir — sold under the brand name Valtrex — cuts transmission of genital herpes by nearly 50 percent.

This is a major boon for herpes patients because their greatest concern is spreading the disease to a partner, said lead author Dr. Larry Corey, head of both the infectious-disease program at Fred Hutchinson Cancer Research Center and the virology program at the University of Washington.

Plus, he added, this is the first time an anti-viral drug has been shown to thwart the spread of a sexually transmitted disease (STD). "It's a paradigm shift. It opens up the question: Can I do this with HIV? Other viruses?"

Preliminary results from the study helped GlaxoSmithKline win federal approval to market Valtrex, used to ease outbreaks of sores, for reducing the spread of genital herpes.

The research, which took place at 96 sites including Seattle, followed nearly 1,500 monogamous, heterosexual couples in which one partner had genital herpes and the other did not. Half of the infected people were given a daily dose of Valtrex and the other half received a placebo. Both groups were urged to use condoms, but few did consistently.

The chance of spreading herpes to a partner was low during the eight-month study, even among the placebo group, perhaps because these were established partners who'd already managed to avoid passing the virus. The likelihood of passing herpes to a partner was 3.6 percent without Valtrex compared with 1.9 percent with the drug.

The drug is not 100 percent effective at preventing transmission, so people with herpes should still tell potential partners about their infection, emphasized Dr. Anna Wald, medical director of the UW Virology Research Clinic and co-author of the study.

Using a condom also can help reduce transmission, by as much as 50 percent in some studies, she said, as can avoiding sexual intercourse during an outbreak of blisters. Wald recommends herpes patients follow all three precautions.

The Valtrex pill can cause headaches, nausea and kidney problems. GlaxoSmithKline, which sells the pill for about $3.50 per day wholesale, sponsored the study.

Dr. H. Hunter Handsfield, head of the sexually transmitted-disease control program for Public Health — Seattle & King County, sees the study as an argument for expanding herpes screening.

"This further shows there's a public-health benefit for people to know they have herpes because they can take steps to protect their partners," he said.

Most STD clinics don't test for the virus unless a patient comes in with visible sores.

Herpes sores are known to be portals for the spread of HIV — the human immunodeficiency virus — so scientists are studying whether another herpes drug can reduce the spread of HIV.

"Herpes needs to be on the front burner of public health because preventing herpes will help prevent the worst STD of all: HIV," Handsfield said.

Julia Sommerfeld: 206-464-2708 or jsommerfeld@seattletimes.com

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