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Polymerase Chain Reaction or
PCR Herpes Test

A PCR herpes test is conducted when someone is having an herpes outbreak. Generally, there are two approaches to diagnosing herpes, either through laboratory tests or through physical examination and history. In a laboratory test, the viruses are detected directly from skin lesions. A swab is rubbed over the sore area. Then it is sent for one of several swab tests called culture, FA, or PCR test. Most authorities feel an accurate laboratory test should be utilized to establish the diagnosis. Physical examination and herpes history are the least reliable means of diagnosing herpes.
Testing for the virus directly from the skin is useful if genital symptoms are present during the time of visit to the doctor. Diagnosing herpes by just looking at a lesion or sore does not give an accurate diagnosis because many other infections or irritations can look just like herpes. As such, and because HSV is a chronic disease, confirmation of the diagnosis with a laboratory test is recommended by almost all medical authorities.

Polymerase Chain Reaction or PCR Tests

Polymerase Chain Reaction or PCR Test is a method used to analyze a short sequence of DNA or RNA even in samples containing only minute quantities of DNA or RNA. PCR herpes test is used to reproduce or amplify selected sections of DNA or RNA. Previously, amplification of DNA involved cloning the segments of interest into vectors for expression in bacteria, and took weeks. But now, with PCR test done in test tubes, it takes only a few hours. PCR test is highly efficient so that untold numbers of copies can be made of the DNA.

PCR Testing for Herpes Diagnosis

PCR herpes testing is the most accurate method for diagnosing herpes. PCR techniques make many copies of the viral genetic material either DNA or RNA in a short time so that even tiny amounts of virus are sufficient for a positive test. This enables PCR to accurately and reliably diagnose herpes. A very short time of only about 4 hours is needed once the specimen arrives in the lab. PCR herpes tests can also tell if HSV-1 or HSV-2 is present. PCR is the only test sensitive enough to find herpes in a lesion that does not contain much virus. This method provides a 23% increase in sensitivity and 100% specificity at correlation to viral culture. It can be done on cells or fluid from a sore or on blood or on other fluid such as the person's spinal fluid. The PCR test is not commonly done on the skin lesions themselves but it is best for testing spinal fluid.

Accuracy and Reliability of the PCR Tests

A study showcased the accuracy and validity of the PCR herpes test. Of over 36,000 specimens that were tested by both culture and PCR test, 3377 were positive by PCR but negative by culture. A lot of the specimens that were positive only by PCR were collected in warmer summer months. Warm transport conditions can harm the virus so that it can't infect culture cells but PCR tests are unaffected. This is another reason PCR test is more accurate than viral culture test.

Pros and Cons of PCR Herpes Tests

Since PCR test is more sensitive than culture or cytology, the virus can be detected for a longer period both before and after an outbreak. The false negative rate of culture detection starts to rise dramatically 48 to 72 hours after an outbreak. Furthermore, Herpes cultures require a separate collection that must be refrigerated. PCR herpes tests are performed directly from the vials, and can be kept at room temperature.

Despite the appealing advantages of PCR testing, it is not widely available and more expensive than culture or FA herpes tests. But PCR is more likely to give you a correct answer. The chance of missing herpes in a lesion by culture or FA is much higher than with PCR. If PCR herpes test is not affordable or available to you, a type specific serology blood test is good alternative to see if you have been infected with HSV.