Clinicians recommend specific screening tests for sexually transmitted infections, but HSV testing is not part of the usual screening. Your clinician will recommend testing individually, based on history and symptoms. If you have symptoms that suggest herpes, she or he can take a swab of an active lesion and send it to a lab for confirmation (Viral culture and DNA tests). If you do not have symptoms but are curious to know if you’ve been exposed to HSV, a blood test will indicate if you have antibodies to it.
What is the HSV test used for and who will need the test?
- The test is to confirm that the sores on the mouth or the genitals are caused by the HSV or not.
- A HSV test may be used to diagnose the infection of a pregnant woman.
- If parents are test HSV positive, new born babies may need to test as well.
- If your sex partner has herpes, you may need the HSV test.
- You may need a test if you have certain risks of sexually transmitted diseases such as multiple sex partners.
Testing in the presence of symptoms:
Viral Culture: If active genital ulcers or sores are present, the vesicle should be unroofed for sampling of vesicular fluid for culture. The diagnostic value of culture is highest in the early stages of disease, when lesions appear as fluid-filled vesicles, and falls rapidly as the lesions begin to heal. Results are generally available within a week. The primary benefit of the culture is its precision in giving a positive result. This means that if you test positive by viral culture, you can be sure about having the virus.
Furthermore, a culture can also be “typed” to determine whether HSV-1 or HSV-2 caused the illness. The major disadvantage, however, is false-negative results. The culture may test negative as the disease progresses, and lesions begin to heal even in the presence of infection.
DNA testing: Healthcare providers can also take a swab of lesions and run DNA tests—known as Nucleic Acid Amplification Testing (NAAT). DNA testing can tell if a person has HSV-1 or HSV-2. As opposed to viral culture, there is less chance of a false negative result with NAATs. NAAT methods are the preferred methods of testing for herpes, with Polymerase chain reaction (PCR) as the most-widely used NAAT method.
Testing with no symptoms:
Specific blood tests are available that can be performed when a person has no apparent symptoms but has concerns about having the illness, or they may want to test themselves before starting a new sexual relationship. Blood tests do not detect the virus; instead, they look for antibodies (made by the body’s immune system in response to infection) in the blood.
IgM vs. IgG:
There are two kinds of antibodies produced in response to infection, IgM and IgG. Ig M is produced first after infection but is very short-lived. IgG appears soon after infection, as levels of Ig M fall, and stays in the blood for life.
IgM tests are generally not recommended: The research shows that IgM can reappear in blood tests in up to a third of patients during recurrent episodes, while it may not appear at all in up to half of persons who have a recent first episode of infection. Therefore, IgM tests can lead to unreliable test results, as well as false presumptions about how and when a person acquired HSV. Hence, we do not recommend using blood tests as a way to determine how long a person has had herpes. Besides, IgM tests cannot precisely distinguish between HSV-1 and HSV-2 antibodies.
IgM tests sometimes cross-react with similar viruses, such as varicella-zoster virus (VZV), which causes chickenpox or cytomegalovirus (CMV), which causes infectious mononucleosis, meaning that positive results may be misleading.
Unlike IgM, IgG antibodies can be reliably broken down to either HSV-1 or HSV-2. Like any blood test, these tests cannot tell whether the site of infection is oral or genital. However, since the lion’s share of genital herpes is by HSV-2, a positive result for type-2 antibodies most likely indicates genital herpes.
