Molecular Testing For Genital Herpes

Molecular Testing For Genital Herpes

Genital herpes is the fourth most common sexually transmitted disease in the UK with over 18 000 new cases reported from genitourinary medicine clinics in 2002. These methods have allowed a better understanding of the physiopathogeny of the disease. Single CVL specimens from 509 women were tested. Details of the investigations carried out at each visit were recorded. RESULTS: HSV was detected at least once in 62 (90%) participants by culture and in 68 (98%) by PCR. Prior or current infection with HSV-1 provides limited protection against HSV-2, though previously infected women remain at risk for new infections (2). Although the prognoses for HSV-1 and HSV-2 differ (see table), infections caused by HSV-1 and HSV-2 cannot be distinguished on clinical grounds alone.

Laboratory testing is necessary to confirm the diagnosis and to distinguish between the two viruses. Despite these major advances, the use of PCR in several clinical situations still needs to be further validated. Observed positive correlation of the presence and quantity of HSV-2 DNA with the presence of active and more severe course of HSV-2 infection may have clinical significance in the evaluation and management of HSV-2 infected patients. Serological testing involves the specific detection of anti-HSV-1 or anti-HSV-2 IgG (and sometimes IgM) antibodies in the blood. Serological testing is highly sensitive, and can be effective for distinguishing acute from chronic HSV infection. However, since by age 40 as many as 20% of women are seropositive for HSV-2 and up to 70% United States adults are HSV-1 seropositive, a significant drawback to serological testing is that it cannot distinguish clinically significant chronic infections from latent infections that occurred in the remote past. Also, since genital and oral infections can both be caused by either HSV-1 or HSV-2, an additional drawback is that serological testing cannot specifically identify genital infections.
Molecular Testing For Genital Herpes

Viral culture has traditionally been considered the diagnostic gold-standard, but is time consuming, requires specialized specimen transport, is labor intensive, and may take up to ten days to yield a result. In addition, its sensitivity, particularly for recurrent or healing lesions, can be as low as 25%. PCR-based testing is more specific for clinically significant HSV infection than serology, because it can definitively identify active genital lesions, regardless of HSV type. PCR-based methods are potentially much faster than viral culture, and specimen preservation and transport is simpler. PCR is more sensitive than culture for detecting HSV infections, both in women with active lesions and for detecting asymptomatic shedding in the absence of a clinically apparent lesion (4). Description: This assay simultaneously detects and differentiates HSV-1 and HSV-2 using real-time PCR technology. An internal control is built into the assay to determine adequacy of the specimen.

PCR is more sensitive than culture, and more specific than serology for the detection and differentiation of clinically significant HSV-1 and HSV-2 infections. Note that a negative result does not eliminate the possibility of latent HSV infection. 3. Brown Z a, Wald A, Morrow RA, et al. Effect of serologic status and cesarean delivery on transmission rates of herpes simplex virus from mother to infant. JAMA: the journal of the American Medical Association. 2003;289(2):203-9.

4. Aumakhan B, Hardick A, Quinn TC, et al. Genital herpes evaluation by quantitative TaqMan PCR: correlating single detection and quantity of HSV-2 DNA in cervicovaginal lavage fluids with cross-setional and longitudinal clinical data. Virology journal. 2010;7(1):328.

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