Genital herpes: a hidden epidemic

FDA Consumer, March-April, 2002 by Linda Bren

All three of the drugs work by interfering with DNA synthesis to prevent the virus from reproducing, says Kukich. Famciclovir and valacyclovir, which are better absorbed by the body, can be taken less often than acyclovir. (For more information on these antivirals, see "Genital Herpes Oral Antiviral Drugs," page 13.)

Diagnosing Genital Herpes

Herpes can be detected by a viral culture of a lesion, if one is present, or a blood test. Ashley recommends both methods.

With a viral culture, a doctor swabs a lesion to pick up cells, puts the swab in a special solution, and sends it to a lab for growing and analyzing.

Although a doctor may recognize a herpes lesion by examining it, a viral culture will confirm the presence and type of HSV, says Ashley. Once they know whether they have HSV-1 or HSV2, people have a better idea of how often they will have recurrences.

But viral cultures do have their drawbacks. If the lesion has started to heal (usually 48 hours after its appearance), the swab may not pick up enough virus and the culture result will be a "false negative." (False positives in cultures are rare.)

A blood (serology) test can be used to confirm a negative culture. It can also be used to diagnose herpes in a person who has no symptoms, who has genital irritation but isn't sure it's herpes, or who has a sexual partner with herpes and wants to find out if he or she has already become infected.

"Diagnosing whether someone has herpes or not is quickly done by a serology test because once you've become infected, an immune-competent [healthy] individual will develop antibodies to the herpes that is infecting them," says Thomas Simms, a biologist in the FDA's Center for Devices and Radiological Health.

Herpes antibodies will usually show up in the blood several weeks after a person first becomes infected. Some blood tests can determine the type of herpes infection, but cannot indicate whether the herpes is oral or genital. So people without symptoms may not know for certain if their herpes is oral or genital.

In the past several years, the FDA has cleared three blood tests that accurately determine if a person is infected with HSV-1 or HSV-2. The HerpeSelect ELISA Kits and the HerpeSelect Immunoblot Kit made by Focus Technologies of Herndon, Va., detect both types. The POCkit Rapid Test made by Diagnology Inc. of Cary, N.C., detects HSV-2 only. (For more information, see "Herpes Blood Tests," page 14.)

Another blood test is the Western Blot. Although not 100 percent accurate, the Western Blot is considered the "gold standard" of blood tests and is used to determine the accuracy of other herpes blood tests that are developed. The University of Washington is the premier institution for performing and interpreting the test. (See "For More Information," page 16, to find out how you can have your blood tested with a Western Blot.)

Many older FDA-cleared blood tests for herpes are still on the market, and many labs use these tests because they are widely available and inexpensive. Although they may be labeled type-specific (can determine whether the infection is HSV-1 or HSV-2), they are not reliable, says Simms.