Diagnosing Genital Herpes
Several tests are available for diagnosing genital herpes, including blood tests and viral cultures (if a lesion is present). Your healthcare provider may also perform a physical exam to look for any signs and symptoms of the condition. Before making a diagnosis, he or she will also consider other conditions that may share similar symptoms, such as scabies, syphilis, or psoriasis.
How Is Genital Herpes Diagnosed?
When diagnosing genital herpes, a healthcare provider will begin by asking a number of questions. This will include questions about:
- Current symptoms you are experiencing
- Your sexual history
- Other medical conditions that you may have
- Any medicines you are taking.
Your healthcare provider will also perform a physical exam to look for signs and symptoms of genital herpes (see Genital Herpes Symptoms).
A genital herpes diagnosis can often be made by looking at the sores. However, some cases are more difficult to diagnose, especially in between herpes outbreaks. In these cases, other tests may be recommended.
Tests for Diagnosing Genital Herpes
Herpes can be detected by a viral culture of a lesion (if one is present) or a blood test. With a viral culture, a healthcare provider uses a swab to get and study material from a suspected herpes sore. This test will confirm the presence and type of herpes simplex virus (HSV). Once you know whether you have HSV-1 or HSV-2, you will have a better idea of how often you will have recurrences.
You may still have genital herpes, however, even if your culture is negative (which means it does not show HSV). For example, 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." In these cases, a blood test may be recommended.
A blood test can be used to confirm a negative culture. It cannot show whether you are having a herpes outbreak, but it can show if you are infected with HSV. Newer blood tests, called type-specific tests, can tell whether you are infected with HSV-1 or HSV-2. Blood tests cannot tell between genital and other herpes infections. Health experts assume, however, that if you are positive for HSV-2, you have had genital infection.
Blood tests can also be used to diagnose herpes in a person who has no genital herpes 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 genital herpes in these cases is quickly done by a blood test, because once you've become infected, an immune-competent (healthy) individual will develop antibodies to the herpes that is infecting them. A blood test can usually detect herpes antibodies four to six weeks after the first infection (testing before that time will not give an accurate result). Over 90 percent of people who become infected test positive within three to four months.
A positive antibody test means that you are infected with HSV and are contagious from time to time. It does not indicate when you were infected with HSV, nor does it indicate which body site is infected (for example, the vagina, penis, anus, or mouth).
(Click Herpes Blood Tests for more information on the different types of blood tests used for making a diagnosis.)