Herpes Simplex Virus (HSV I & HSV II)

HSV DNA Testing:
HSV DNA testing detects HSV genetic material in a patient sample. This method can gneotype the virus, identifying HSV I and HSV II in circumstances where the virus is present in low numbers (such as a viral encephalitis) or if the lesion is several days old. Also, 90% of women who shed HSV in their genital tract are asymptomatic.

HSV by PCR Advantages:

  • PCR is 25% more sensitive than culture.
  • Whereas the culture requires quick access to the lesions, PCR does not require as many virus particles for accurate testing. This allows more time between lesion outbreak and sample collection with a lower false negative rate.
  • Culture methods require refrigeration of specimen prior to testing. PCR testing eliminates this requirement.
  • PCR gives you the ability to work with non-culture specimens, such as liquid based cytology specimens and most swabs.

HSV Testing and PCR:
Herpes simplex virus (HSV) is one of the most prevalent viruses found in the general population today. In 2015 the World Health Organization estimated that over a billion people between the ages of 15-49 years have genital infection caused by either HSV-1 or HSV-2. Type I infections usually involve non-genital areas, whereas type II infections are primarily found in genital areas, although there is overlap between the two types. The clinical courses of acute first-episode genital herpes among patients with HSV I and HSV II infections are similar and both can cause symptomatic or asymptomatic rectal and perianal infections. HSV infections may be unapparent because symptoms do not always follow a typical pattern or patients may be asymptomatic. By utilizing polymerase chain reaction (PCR), HSV has been demonstrated in asymptomatic patients on 28% of days tested versus 8.1% by viral isolation. As a result, the rate of detection for PCR is 3.5 times that of a traditional viral culture in asymptomatic patients. More importantly, asymptomatic shedding was shown on 60% of days where HSV DNA was measured by PCR. This has a significant impact on patient counseling since asymptomatic shedding of HSV DNA can occur to a much broader extent than previously thought. Patients with ulcerative lesions have positive PCR results on 15 of 17 days (88.2%) versus positive culture results on 3 of 17 days (17.6%).

PCR offers a rapid and sensitive way to test for HSV infections and has evolved to become the standard of care in patients with suspected infection. Studies have shown that range of sensitivity of PCR detection for HSV DNA to be from 75% to 100% with the specificity of 100%. In conclusion, the detection of HSV DNA by PCR has been proven to be the most specific, rapid, and sensitive means to diagnose anogenital and CNS infections.

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