HERPES TESTS
There are two types of herpes tests readily available, a culture and a blood test. Both tests have advantages and disadvantages. This information sheet should help you understand the differences between the tests to decide which one is right for you.
CULTURE
A "culture" is when fluid from a suspected herpes blister is grown at the laboratory and then examined to determine if herpes virus is present. You must have a current outbreak for a culture to be done. If the test is positive, it is a true positive, meaning that you do have herpes. If test is negative, it may be a false negative, meaning you may or may not have herpes. The accuracy of a culture drops by 50% if the outbreak has been present four days or longer. Because a culture is done from the lesion itself, the test will determine specifically which type of herpes is causing the outbreak. It cannot tell how long you have been infected.
BLOOD TEST
In a blood test, the liquid part of the blood is examined for antibodies that the body develops after being infected with herpes. You do not have to have a current outbreak to have the test done. If the test is negative, it is a true negative, meaning that you do not have herpes. If the test is positive, you may or may not have herpes. In some cases we can determine that it is a true positive, that you do have herpes. But other times there may be a cross reaction with other herpes viruses such as chicken pox (herpes zoster) or mononucleosis (Epstein-Barr virus), giving a false positive result. Although a blood test can tell which types of herpes you are infected with, it cannot determine at what site you are infected with them. You could have type 2 orally or type 1 genitally. The test can determine if you were likely infected in the last 6 months or if it has been longer than that. But it cannot tell the difference between an infection that occurred 5 years ago and one that occurred 10 years ago.