Testing people for the genital herpes virus, and encouraging them to tell their partners the results, may help control the spread of the infection, new study findings suggest.

It’s estimated that at least 20 percent of U.S. teenagers and adults have been infected with one of the genital herpes viruses, usually the form known as herpes simplex virus type 2 (HSV-2). Because the sexually transmitted infection often causes mild symptoms or none at all, many people are unaware they’re infected.

It’s been unclear whether people who get tested and tell their partners are less likely to pass on the virus. “This question has never been addressed before,” said lead study author Dr. Anna Wald of the University of Washington in Seattle.

For their study, she and her colleagues questioned 199 men and women with newly diagnosed genital herpes about their sexual relationships in the month before they developed symptoms.

The researchers found that in 13 percent of the cases, patients had known their partner had the virus. And transmission took significantly longer in these couples.

Among patients whose partners had not informed them, transmission typically occurred two months after the couple started having sex, versus about six months among patients who knew about their partner’s infection. That delay meant that the risk of HSV-2 transmission among these couples was half that of the others, Wald said.

She and her colleagues report the findings in the Journal of Infectious Diseases.

There is no cure for genital herpes, and HSV-2 remains in the body for life, though there are drugs that can suppress the virus and prevent future outbreaks of symptoms. Those symptoms include sores in and around the genitals, pain and burning in the affected area and difficulty urinating.

Many people, however, have no obvious symptoms and are likely to remain unaware they carry the virus.

Doctors are still debating whether blood tests that detect HSV-2 should be given routinely to screen symptom-free individuals. But people who suspect they may be at risk can ask their doctor about getting tested, Wald said.

“There are really three things we can do to address the HSV-2 epidemic,” she told Reuters Health.

Besides testing and disclosure to partners, she said, people should consistently use condoms, which cut the risk of transmission significantly, though not completely. In addition, people with genital herpes can take antiviral medications that suppress HSV-2 and reduce - but don’t eliminate - the risk of infecting someone else.

SOURCE: Journal of Infectious Diseases, July 1 2006.