III. Labs: Definitive HSV Diagnosis

  1. Sample collection
    1. Unroof Vesicles with scalpel or needle tip and apply viral culture swab
  2. HSV Polymerase chain reaction (HSV PCR, preferred)
    1. Test Sensitivity: 95% (similar Test Specificity)
    2. Provides more rapid results than viral culture or Direct Fluorescence
    3. Used in HSV Encephalitis diagnosis for rapid results
  3. HSV Viral Culture of vesicular fluid
    1. HSV PCR is preferred over culture
    2. Differentiates HSV I from HSV II
    3. Expect viral growth within 5 days (range 3-10 days)
    4. Test Sensitivity: 50-75% (90% in primary episode)
      1. Vesicles are most concentrated with infection within first 48 hours
      2. Early ulcerative stage may yield a positive result
      3. Not useful in lesions beyond 5 days old
  4. Older tests replaced by HSV PCR
    1. Tzanck Smear of Ulcer scraping
    2. HSV Direct Fluorescent Antibody
      1. Test Sensitivity: 80-90% of viral culture positive
    3. Rapid Giemsa (Dif-Quik) stain
      1. Multinucleated giant cells
      2. Test Sensitivity: 40-77%

IV. Labs: Presumptive HSV Diagnosis - Type specific HSV Serology

  1. Tests
    1. HSV Western Blot
    2. Glycoprotein G-specific HSV Serology
    3. Older HSV IgG and IgM are out-dated and are not recommended
  2. Incidence of positives
    1. HSV I: 90% of adults are positive
    2. HSV II: 30% of adults positive
  3. Indications
    1. Confirm HSV where history is questionable
    2. Partners of Genital Herpes patients
    3. High risk patients (multiple sexual partners, HIV positive, HIV Risk Factors)
    4. Recurrent lesions, but negative HSV PCR or culture
      1. More useful if positive Serology for HSV II
      2. Positive Serology for HSV I does not identify infection site (oral or genital)
  4. Disadvantages
    1. USPTF and CDC do not recommend routine use (esp. since HSV I causes >50% of Genital Herpes)
    2. Antibodies form with weeks of primary infection
    3. Does not differentiate acute infection from prior infection
  5. Interpretation
    1. Primary Herpes Simplex Infection may result in a four fold increase in acute over convalescent Antibody titiers

V. Resources

  1. CDC Genital Herpes Screening
    1. http://www.cdc.gov/std/herpes/screening.htm

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