To order a copy of the Herpes Testing Toolkit, visit the ASHA online store. The resource explains the increasing role of type-specific herpes serologic assays, presents clinical scenarios in which serologic testing are beneficial, and reviews key factors in a differential diagnosis for genital herpes. To determine which test might be best for your situation - or to show your doctor which tests are available (since herpes is not routinely included in STD screenings), you can download and print ASHA's Herpes Blood Test Guide.įor healthcare providers, we've developed the Herpes Testing Toolkit, which was reviewed by leading experts in this field. ASHA has created a quick reference guide to herpes blood tests, including a chart that outlines and compares the accurate, FDA-approved type-specific blood tests available for herpes simplex antibodies. It may be necessary to request on of these tests by name from your healthcare provider. However, since most cases of genital herpes are caused by HSV-2, a positive result for type-2 antibodies most likely indicates genital herpes. Like any blood test, these tests cannot determine whether the site of infection is oral or genital. There are currently several FDA-approved, gG-based blood tests that can give accurate results for herpes. 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. 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 one person, it could take just a few weeks, while it could ta ke a few months for another. The challenge here is that the time it takes for IgG antibodies to reach detectable levels can vary from person to person. But 100% of the labs using gG-based tests accurately reported that the blood sample was negative for HSV-2 (see reference 2). A recent study corroborates this finding: labs that used non-gG-based tests for herpes had high false-positive rates for HSV-2 antibodies (14-88% saying the blood sample was positive for HSV-2) in samples that were actually only positive for HSV-1 antibodies. Unlike IgM, IgG antibodies can be accurately broken down to either HSV-1 or HSV-2. The accurate herpes blood tests detect IgG antibodies. IgM tests sometimes cross-react with other viruses in the same family, such as varicella zoster virus (VZV) which causes chickenpox or cytomegalovirus (CMV) which causes mono, meaning that positive results may be misleading. A person who only has HSV-1 may receive a false positive for HSV-2.ģ. already has antibodies to HSV-1, the primary cause of oral herpes. This is important in that most of the adult population in the U.S. In addition, IgM tests cannot accurately distinguish between HSV-1 and HSV-2 antibodies, and thus very easily provide a false positive result for HSV-2. Unfortunately, most people who are diagnosed will not be able to determine how long they have had the infection (see reference 1).Ģ. For this reason, we do not recommend using blood tests as a way to determine how long a person has had herpes. Therefore, IgM tests can lead to deceptive test results, as well as false assumptions about how and when a person actually acquired HSV. However, research shows that IgM can reappear in blood tests in up to a third of people during recurrences, while it will be negative in up to half of persons who recently acquired herpes but have culture-document first episodes. Many assume that if a test discovers IgM, they have recently acquired herpes. IgM tests are not recommended because of three serious problems:ġ. IgM is actually the first antibody that appears after infection, but it may disappear thereafter. IgG appears soon after infection and stays in the blood for life. Blood tests can look for and detect these antibodies, as the virus itself is not in blood. IgG When an individual contracts herpes, the immune system responds by developing antibodies to fight the virus: IgG and IgM. Blood tests do not actually detect the virus instead, they look for antibodies (the body's immune response) in the blood. Blood tests can be used when a person has no visible symptoms but has concerns about having herpes.
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