To answer whether a patient has HSV disease, false positive diagnoses can be avoided if tests are performed in high-probability of disease situations and NOT as simple screening tests! And, proper samples must be obtained. If the sample be a blood specimen, the disease state must have had sufficient time to mount an antibody response (in an immunocompetent patient). If the sample be of tissue, it must contain viropathic cells containing a sufficient viral load to be visible in DFA tests or amplifiable in molecular tests (such as PCR). Via this link, place HSV in the top left search box to see the many test modes for HSV (HERE).

Patients & physicians often present with ACUTE lesions &, directly or indirectly, want to know if it is herpetic. Local gynecologic speakers tell us that acute, apparently "first" lesions, can be managed as if herpetic until several weeks later when serologic testing can then be performed at a time when the antibody level has become detectible. Or they want to know if a CHRONIC HSV status is type I or II. Type I tends to infrequently recurr; type II tends to frequently recurr.

In our lab, this " Herpes Select 2" is a type-specific western-blot-like "strip immunoblot" patient's-serum-test only for IgG antibodies (at a certain height or higher³). It differentiates between HSV I & II by antibody detection of either the IgG HSV I type specific glycoprotein gG-1 or the IgG HSV II type specific glycoprotein gG-2. The reagent antigens are by recombinant preparations (Focus Technology's HerpesSelect Immunoblot [IB] strip tests). Color producing reactions are by ELISA. The one for HSV II has, by comparison to UW-WB testing, a sensitivity of 97-100% and a specificity of 94-98% in clinical trials. We started reporting this test from LML on 29 October 2004. [HSV testing]

1. persons (1) with a lesion NOT due to herpes & (2) who have never had HSV II.
2. HSV II infected persons whose Ab level has not yet reached detectibilty.
3. previously infected persons who (1) did not mount a detectible level of Ab (may or may not be "immune") or (2) whose antibody level has receeded to nondetectible levels.
4. previously infected persons who have become seriously immunocompromised and cannot produce detectible levels of IgG Ab.

 Elevated, reactive, or positive results:

1. represents true evidence of HSV II present or past infection.
2. false positive of undetermined etiology: the lower the disease prevalence in the population of the tested patient (high prevalence in STD clinic...expected low prevalence in children), the lower the positive predictive value (example: a positive test of 98% specificity when the expected disease prevalence is only 3% has a positive predictive value of just 0.61).

References:

1. Ashley RL, "Performance and Use of HSV...", Herpes 9 (2):38-45, 2002. (JBC & LML)
2. Focus Diagnostic's website about this.
3. Carter JB, memo, "Various LML QA Projects, Summer 2012", 17 January 2013.

(posted 30 October 2004; lates adjustment, 21 January 2013)