Herpes Confirmation Testing: A viewpoint from our Medical Advisory Board

March 29th, 2011  |  Published in STD Testing

Few if any laboratory tests are perfect; most of them carry the potential of either positive or negative results that are not reliably true, called “false positive” and “false negative”, respectively. For the genital herpes antibody tests, false-positive test results are not infrequent. This leads to a legitimate question: Is it possible to assure that a “positive” genital herpes test is truly positive?

Standard testing for type 2 herpes simplex virus (HSV-2), the usual cause of genital herpes, involves a blood sample using a method called ELISA (enzyme-linked immunosorbent assay). ELISA produces a numerical result called the ELISA ratio:

  • ELISA ratio below 0.9 indicate a negative result, i.e. absence of antibody to HSV-2
  • ELISA ratio between 0.9 and 1.1 is indeterminate; antibody to HSV-2 may or may not be present
  • ELISA ratio over 1.1 indicate positive; antibody to HSV-2 is present

There has always been controversy among experts regarding the ELISA ratio and what should be considered positive. Originally, the manufacturer of the most commonly used HSV antibody test in the U.S. (HerpeSelect brand, produced by Focus Technologies) submitted data to the U.S. Food and Drug Administration showing results with ELISA ratio values over 1.1 were indeed positive for HSV-2. However, herpes and laboratory science experts now understand that HSV-2 test values between 1.1 and 3.5 are sometimes false-positive. The lower the value, the more likely the result is false, even though technically considered positive by the accepted ELISA ratio value. “This is a significant finding,” says H. Hunter Handsfield, MD, a member of STDtesting.com’s Medical Advisory Board, a division of the Institute of Sexual Health.

“However, it is important to treat positive results in this range as true positives in order to minimize the possibility of transmitting infection to your partner. If you have concerns that it may not be a real positive, utilize confirmatory testing immediately and if negative, retest in 3-6 months,” according to Barbara Van Der Pol, PhD, MPH, also a member of STDtesting.com’s Medical Advisory Board. Low positive test results may occur in early stages of infection before a full immune response is established.

Why isn’t the index changing?

As a result of this new information, many U.S. researchers studying herpes infections now use the higher ELISA ratio value of 3.5 to define whether a patient is infected with HSV-2. However, the official index values remain unchanged. Much of the data concerning changing the interpretation of this result comes from work being performed overseas. It is unclear if different populations have different “background” levels of reactivity that would require a change to the official interpretation.

According to Handsfield, Focus Technologies submitted the original index data to the U.S. Food and Drug Administration showing results with ratio values over 1.1 were positive for antibody to HSV-2. The interpretation of Herpes test results have been based on these index values ever since.

“FDA regulations do not permit the manufacturer to change their ‘normal’ values unless they conduct further research, submit those results to the FDA, and request a change in the approved labeling of the product. Usually they must do their own research, as published studies by other researchers often do not meet FDA’s regulatory standards and the results usually are not acceptable to the FDA,” said Handsfield. “Such studies generally are expensive and time- consuming. Therefore, the official information provided by the manufacturer, approved by FDA, and used by laboratories nationwide continues to state that any ELISA ratio over 1.1 is positive. However, experts in STDs and infectious diseases now know that only values 3.5 and greater are definitively positive for HSV-2.”

How do I know if my test is really positive?

At STDtesting.com, we consider HSV-2 ELISA results 3.5 or greater to be positive. No other testing is necessary.
However, some tests in the 1.1 to 3.5 range may be false-positive. Individuals with herpes test results in this range now have the option of taking a herpes confirmation test - new to the marketplace - to confirm results for HSV-2 infection.

Does STDtesting.com offer the herpes confirmation test?

Yes, STDtesting.com is the first commercial online diagnostics company to bring the herpes confirmation test to market for consumers.

“However, not everyone with an uncertain ELISA result needs a confirmatory test. If an ELISA value from 1.1 to 3.5 fits with other evidence of HSV-2 infection (for example, someone experiencing typical symptoms of recurrent genital sores), often no further testing is necessary. But if a low-positive ELISA result doesn’t fit with other evidence, e.g. if there are no symptoms of genital herpes, confirmatory testing often makes sense.    Confirmatory testing is not recommended for persons with definitely positive initial tests, i.e. ELISA ratio above 3.5,” says Handsfield.

Does STDtesting.com use the HerpeSelect brand to test for genital Herpes?

The type of genital herpes test used by STDtesting.com is dependent on the specific lab location chosen by the customer during the ordering process. Since STDtesting.com partners with the two largest national labs, the HerpeSelect product is often administered; similarly to what doctors and hospitals order nationwide.
It is less certain whether confirmatory testing is needed in those tested with other methods, such as the HSV Captia brand test. However, STDtesting.com’s medical advisory team recommends a similar approach as for those tested with HerpeSelect.

How can I learn more about Herpes testing and the herpes confirmation test?

If you’d like to learn more, you can ask our expert panel online free of charge. Also, with all STD tests ordered through STDtesting.com, free phone consultations with our network of physicians are available to help interpret herpes test results.

If you are experiencing symptoms of possible genital herpes – or have any concerns despite having no symptoms - you may decide to undergo HSV-2 testing. Herpes symptoms in women and herpes symptoms in men are similar and occur in the form of a herpes outbreak. Pain or itching in the genitals, buttocks or inner thighs leads to small sores and ulcers. Women may also experience vaginal herpes as well as herpes labial.

Early testing and accurate diagnosis is the key to living with herpes and getting access to the appropriate herpes medication to help manage symptoms and herpes outbreaks. Early testing and treatment also reduces the health complications related to HSV-2, including genital warts in men and genital warts in women.
Undergoing a herpes test is the only way to receive an accurate diagnosis for Herpes simplex virus type 2 (HSV-2)—the common cause of genital herpes.

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