The Science of Sex: Herpes

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Genital herpes is one of the plagues of the sexual revolution. Nearly one-quarter of the adult population of the U.S. is now infected with herpes simplex virus type 2 (HSV2 — HSV1 is usually associated with sores on or in the mouth). Of these HSV2-positive people, 10 to 25 percent report that they have had symptoms of the disease. A new study by a leading herpes researcher offers disturbing new insights into how the disease spreads so easily.

The main symptom of HSV2 is the recurrent breakout of a clump of blisters on the outer or inner labia, clitoral hood, vaginal walls or cervix (in women), the penis (in men) or the buttocks or skin around the anus (in either sex). Infections of the mouth can also occur. After a day or so, the blisters break, forming weeping ulcers, which then crust over and gradually heal.

Herpes is not life-threatening, except for infants who acquire it from their mothers during childbirth. Even in adults, though, the breakouts can be quite painful. And once a person is infected, recurrent bouts can be expected. The most obvious means to prevent transmission is to abstain from sex while one partner has a breakout, and for a few days thereafter. Condoms are also useful, since the HSV2 virus cannot penetrate latex, but it can infect skin adjacent to the base of the condom.

According to virologist Anna Wald, however, an HSV2-infected person can transmit the virus to others during the intervals between breakouts. Transmission can even occur, she says, if the herpes-infected person has no recollection of ever having had a breakout. In the latter case, the person is usually unaware that he or she harbors the virus at all.

Wald, who is director of the Virology Research Clinic at the University of Washington, is the lead author of two major papers on HSV2 published in the New England Journal of Medicine: one appeared in 1995, the other on March 23 of this year.

In the 1995 study, Wald’s group followed 110 women who suffered recurrent breakouts of genital herpes. The women collected swabs from their genital and anal areas every day for several months, and also kept a diary of their herpes breakouts. The researchers detected the presence of HSV2 on about a quarter of all days during breakouts, but also on about 2 percent of days between breakouts. Because the intervals between breakouts were much longer than the duration of the breakouts, nearly one third of all HSV2-positive days were between breakouts. Recently infected women, and women with more than twelve breakouts per year, were particularly likely to secrete the virus between breakouts.

In the more recent study, Wald and her colleague turned their attention to fifty-three women and men who were HSV2-positive (on the basis of blood tests) but who claimed never to have experienced any symptoms of herpes. At the beginning of the study, the researchers carefully instructed the subjects on how to look for herpes lesions. As in the previous study, the subjects collected swabs from themselves every day for several months.

It turned out that most of the subjects, once instructed what to look for, did notice that they were having periodic breakouts. As in the previous study, most of these men and women secreted detectable levels of HSV2 on at least one occasion between breakouts. But of the seven subjects who did not notice any breakouts during the study, four still secreted HSV2 at least once. Thus, most “asymptomatic carriers” do in fact suffer from herpes like other HSV2-positive men and women.

It’s important to note, however, that the researchers studied only the secretion of the herpes virus by their subjects, not its transmission to their sex partners. Several previous studies have documented that HSV2 can be transmitted between breakouts, but the probability of such transmission, compared with transmission during breakouts, remains unclear. There may be factors increasing the likelihood of transmission during breakouts: these factors could include a greater number of virus particles, the presence of exudate and so on.

Because less than a quarter of HSV2-positive persons know they have herpes, the majority of herpes infections come from people who don’t know they have the disease, according to Wald. Thus honest communication between partners may not be the complete answer to curbing the spread of the disease.

It is still a good possibility, however, that most infections occur when the HSV2-positive person is experiencing a breakout, whether that person is aware of it or not. If people were better educated about herpes and encouraged to examine themselves regularly, the spread of the disease could probably be significantly curbed by the simple rule: either sex with condoms or no sex during breakouts.

Whether sero-opposite couples (one carrying the virus, one not) should use condoms at all times is a more difficult question, which further research on transmission of the virus may clarify. According to Wald, however, the answer to this question is an unambiguous yes.