Q: My boyfriend has genital herpes, and he occasionally has an outbreak that appears as a sore on his penis. Is this when he is contagious?
A: It’s when he is most contagious — but he is also contagious when he doesn’t have an outbreak.
A quarter of U.S. adults over 18 are infected with genital herpes, also known as herpes 2. But 90 percent of them don’t even know they are infected.
The classic outbreak appears as a small, open sore or ulcer. The virus “maintains its residence” in a nerve root, and when it becomes active and reaches out to the surface, it goes to the area supplied by that nerve. That’s why, if a lesion recurs, it does so in the same place time after time.
Not everyone with genital herpes, however, notices identifiable symptoms. Some have a very mild irritation — redness, tenderness or itching — which they attribute to things like insect bites, friction burns, yeast infections or “recurrent shingles” (even though there is no such thing). Others are completely symptom-free.
These are the individuals who are most likely to spread the virus, because they are likely to take no precautions. That said, about 70 percent of new infections are due to viral shedding — the period when the virus is most likely to be transferred to another person — by people with accompanying clinical signs.
Consequently, you may already have the virus. A doctor can determine this with a blood test for Herpes 2 (Ig), a type-specific immunoglobulin. If you are already infected, you won’t be at risk for a new infection — you and your boyfriend already share the virus. But knowing your herpes status will tell you whether you are capable of infecting a future partner.
Many monogamous couples think that if they abstain from sex or use condoms when one partner has an obvious herpes lesion, the other will be safe. This is not so.
Studies that tested for the silent presence of the virus on genitals have shown that a person with genital herpes sheds the virus about 15 percent of the time. Half the shedding occurs just before, during or after an outbreak, but half occurs completely at random.
Even if the couple avoids intercourse during outbreaks, the approximate rate of transmission is 10 percent a year (if the man is affected) or 4 percent a year (if the woman is affected). In other words, in one year, 10 percent of women and 4 percent of men will get herpes if their mate has it.
Regular condom use can reduce these transmission rates by about 50 percent.
To reduce the rate even more, your boyfriend can consider daily anti-herpes viral therapy with Valacyclovir (Valtrex). This medicine keeps herpes at bay, clears it up quickly and appears to reduce transmission by 50 percent to 75 percent.
Still, there is no guarantee that you are at zero risk of infection.
The broader issue is whether, if you do get infected, herpes will ultimately harm your health. Although I don’t want to trivialize this infection, in your general scheme of health, it probably will not. The major concern is that if you are pregnant and develop a new outbreak of herpes, the virus can be transmitted to the fetus, especially during vaginal delivery. What’s more, people with genital herpes have a much greater risk of acquiring HIV if they are exposed. (It’s theorized that the lesion causes microscopic breaks in the skin, allowing HIV to enter the body.)
Dr. Reichman’s Bottom Line: In most cases, genital herpes is more of an annoyance than a true health threat. There are ways to lower the risk of transmission — and if you do catch it, it is both treatable and manageable.
Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," published by William Morrow, a division of .
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.