In parts one and two of this series, we've described genital herpes as a subtle but widespread infection. In this installment we explain how it's spread from person to person and what you can do to lower the risk of transmission.

How herpes is transmitted

To paraphrase virtually every educational piece ever written about genital herpes, this infection spreads from one person to another through direct body-to-body contact--almost always sexual contact. Educational materials often use the phrase "skin-to-skin" when describing this process, but it's important to remember that HSV can be present on the surface of mucous membranes like the lining of the vagina or anus--places we may not think of as "skin."

Genital herpes infections can result from contact that occurs through intercourse, though oral-genital sex, and through anal sex. Herpes may also be spread through body-to-body contact that does not involve penetrative sex, such as various kinds of foreplay, but it is not casually transmitted during handshakes or other non-sexual activities.

Is a person with herpes always contagious? No. HSV actually spends a good deal of time sleeping--hiding away in the nerve roots in a mostly harmless state of latency. HSV can be transmitted only when the virus becomes active and migrates from these hiding places to the surface of the skin or to mucous membranes such as the vagina.

Sometimes it's obvious when the virus has become active, because it causes blisters, or sores, or some other kind of skin lesion. But--sad to say--herpes is tricky enough to become active without causing symptoms, so one doesn't always know when the virus is contagious.

Reducing the Risk

Couples in which one partner has herpes often wonder what they can do to reduce the risk that herpes will be spread from one to the other.

Prevention advice used to be easier when scientists believed that herpes was contagious only when symptoms were present. In those days, the formula was simple: avoid sex when you're having an outbreak. Today, with the knowledge that herpes might be spread during aymptomatic periods, we also have to be concerned about what couples do in between outbreaks. The following list offers a number of options that experts say can reduce the risk of spreading herpes:

1. If you know you have herpes, tell your partner: Ideally, both partners will understand the basics of herpes prevention and make decisions together about which precautions are right for them.

2. Abstain from sex when symptoms are present: Having sex during an outbreak puts an uninfected partner at risk.

3. Use condoms between outbreaks: Condoms help protect against unrecognized herpes by protecting or covering the most likely sites of transmission. They can also help prevent other sexually transmitted infections. However, condoms do not provide 100% protection because, for one thing, a lesion may be in a place the condom doesn't cover.

4. Consider medication. If taken daily, antiviral medications (acyclovir, Valtrex, Famvir) help prevent outbreaks and reduce the recurrence of virus on the skin and mucous membranes. At this stage, no one should regard daily antiviral therapy as a guarantee of safety, but studies are under way to find out whether one of these antivirals, Valtrex, can also reduce the risk of herpes transmission.

The 'real world'

Some also ask about using spermicides as a form of STD protection. The spermicides used in contraceptive foams, films, and gels kill HSV in lab tests. However, questions have been raised about the safety of spermicides, and it's not known if spermicides can truly help prevent the spread of herpes in "the real world."

And what if you're out there, dating--wondering? You may have no reason to believe that you or a partner has herpes, but you may puzzle over what you can do to keep from getting it. Abstinence is one approach. Another is consistent condom use. Condoms, though not perfect, are probably the best all-around method of lowering the risk of acquiring or spreading herpes for those who are sexually active.

But, remember, herpes is quite widespread and can be very subtle. If you come across a pattern of recurrent symptoms in yourself or your partner, it may be a good idea to get one of the type-specific blood tests described in part two.

-- Charles Ebel