What is considered the BEST test for diagnosing HSV1/HSV2?

• A. PCR
• B. Tzanck smear
• C. Urine NAAT
• D. Serology

Answer: (B)

When diagnosing HSV infections, the most reliable test is nucleic acid amplification testing for HSV DNA from the lesion or involved fluid (PCR). PCR has the highest sensitivity and specificity, can detect low levels of virus, and can distinguish HSV-1 from HSV-2, which helps guide prognosis and management. It’s the preferred test for acute mucocutaneous HSV lesions and for suspected HSV encephalitis because it remains accurate even after early antiviral therapy.

A Tzanck smear can indicate herpes-like viral infection by showing multinucleated giant cells, but it cannot differentiate HSV from VZV, cannot determine the viral type, and has limited sensitivity and specificity. Therefore it’s not the best choice for definitive diagnosis.

Urine NAAT isn’t used to diagnose HSV, and serology reflects past exposure rather than an active infection, so neither is appropriate for confirming active HSV disease.