Accurate testing is important for genital herpes. Being told you're infected when you're not, or the other way around, can be awful. Some people have lived decades under the false impression that they were infected because a doctor didn't test them for the virus. Instead, they were diagnosed by their symptoms alone. It's easy to mistake genital herpes symptoms for something else.
If you have sores on your genitals, a doctor can take a sample from a sore and look for the herpes simplex virus (HSV) in it. One test is called a cell culture. Any viruses in the sample are allowed to multiply so that they're easy to find under a microscope.
The direct fluorescent antibody test is another kind. A solution containing HSV antibodies and a fluorescent dye is added to the sample. Antibodies are proteins produced by the immune system in response to an infection. If the virus is present in the sample, the antibodies stick to it and glow when viewed under a special microscope.
These tests are good because they can tell the difference between the two types of HSV. It's important to know which type you have. If you're infected with type 2 (HSV-2), you may have outbreaks more often than would if you had type 1 (HSV-1). What's more, knowing which type you have gives a clue as to how you were infected. HSV-1 usually infects the genitals through oral sex, and HSV-2 usually is passed on during vaginal or anal sex. For help with these terms, see the Glossary.
These tests may give a false-negative result if the sores have begun healing, or if it's not the first time you've had symptoms. A positive result from one of these tests is very accurate, however.
Blood Tests for Genital Herpes
A blood test can detect HSV antibodies even when you have no symptoms. A false-negative result from a blood test is possible if you have been infected recently. It takes several weeks for HSV antibodies to show up in the blood.
False-positive test results are possible, too. If you test positive, but your risk for getting the virus is low, you may need to be tested again.
Tzanck and PCR Tests
Other ways to detect the herpes virus include the Tzanck test and the PCR test. A Tzanck test places a sample from a sore on a microscope slide and stains it with a dye. Cells that are infected with HSV look different from those that aren't. This test is not very accurate, so health experts don't recommend it.
The PCR (polymerase chain reaction) test looks for pieces of the virus' DNA. It's an accurate test, but doctors have not decided how it should be used to diagnose genital herpes, so it's not the preferred method.
Tzanck and PCR Tests
New tests on the horizon include one that can detect HSV in saliva and urine. It was developed recently by a doctor at the London School of Hygiene and Tropical Medicine for use in a safe-sex study in Africa. The test has not been marketed to the public.
