"I’m not really sure if I have herpes. How can I know for sure?"
Before you consider getting a blood test for herpes, if you have a rash of something resembling a herpes outbreak (bumps, lesions, sores, etc.), the absolute best way to know for sure if you have herpes or not is to get it cultured (swabbed with a Q-tip and tested) by your doctor. This is the best way since it comes straight from the source. A blood test (aside from it taking around 3 months for herpes antibodies to build to detectable levels) will simply tell you if you have HSV-1 or HSV-2 (or both). It won’t tell you in which location the virus might show up (orally or genitally or neither — 15-20% of people never have an active herpes outbreak, but herpes viral shedding does still occur).
The IgG Blood Test for Herpes
The most well-known blood test called the IgG test. This herpes test looks for antibodies in the blood that would be present to specifically combat the herpes virus. This test can tell you which type of herpes you have, whether HSV-1 or HSV-2 (either can show up on either the lips or genitalia, but HSV-1 prefers oral and HSV-2 prefers the genitals).
But the tests need time from herpes exposure to test in order for the antibodies to build up in the blood to be detectable. Here’s a quote from the ASHA message boards: “The challenge here is that the time it takes for IgG antibodies to reach detectable levels after initial infection can vary from person to person. For one person, it could take just a few weeks, while it could take a few months for another. So even with the accurate tests, a person could receive a false negative if the test is taken too soon after contracting the virus. For the most accurate test result, it is recommended to wait 12-16 weeks from the last possible date of exposure before getting an accurate, type-specific blood test in order to allow enough time for antibodies to reach detectable levels. False positives are rare with type-specific blood tests when used in this manner.”
The Western Blot Blood Test for Herpes
There is also another blood test called the Western Blot that is even more definitive than the IgG, but will cost you more out of pocket. Here’s what the University of Washington has to say (they process the Western Blot results):
“The HSV Western blot uses HSV-1 and HSV-2 proteins which have been separated by size so that type-specific antibody profiles can be recognized with a specificity of >99%. This method may be used to distinguish maternal from infant antibody profiles and to distinguish serum and cerebrospinal fluid profiles of HSV antibodies. This test has been exhaustively validated in studies of well-characterized patient populations. It is the current gold standard HSV serology and provides a highly accurate confirmatory test for positive results by ELISA.”
From the University of Washington FAQ page.
How is HSV diagnosed?
There are three common ways HSV infections can be diagnosed. One way is by a visual examination conducted by a health care provider. This diagnosis should always be confirmed by a lab test. The “gold standard” to diagnose herpes is through a herpes culture, but the result can be negative even though someone has HSV. A positive culture should identify whether the infection is HSV-1 or HSV-2. Finally, blood tests can detect antibodies to HSV. The antibodies may not develop until two months after someone has become infected. The Western Blot, the most accurate of these blood tests, is done at the University of Washington.
Where can I get tested?
You can have your blood tested with a Western Blot at the University of Washington Virology Lab. To do this, have your health care provider call #206-598-6066 to request the HSV Type-Specific Serology information packet. Other accurate tests for HSV-2 may also be available through your local healthcare provider.