Herpes Simplex and Varicella-Zoster Screening: Methods and Interpretation

Herpes Simplex Virus (HSV-1/HSV-2)

• Serology (IgG): Type-specific (gG-1, gG-2). Positive = past infection. Does not indicate site or activity. IgM = recent (but unreliable, not recommended).
• Viral Culture: Gold standard for active lesions; low sensitivity late.
• PCR (NAAT): Preferred for CSF (encephalitis), genital lesions; high sensitivity/specificity.
• DFA (Direct Fluorescent Antibody): Rapid, lesion scrapings; lower sensitivity than PCR.

Varicella-Zoster Virus (VZV)

• Serology (IgG): Immunity (past infection/vaccination). IgM = acute (varicella or zoster).
• PCR: Preferred for CSF (VZV encephalitis, vasculopathy), vesicle fluid.
• Culture/DFA: Less sensitive; historical.

Clinical Decision

• Screening asymptomatic: IgG only (pregnancy, immunosuppression, occupational)
• Active lesions: PCR > culture > DFA
• CNS disease: PCR on CSF