Significance and Clinical Relevance of the Detection of Herpes Simplex Virus DNA by the Polymerase Chain Reaction in Cerebrospinal Fluid from Patients with Presumed Encephalitis

The polymerase chain reaction (PCR) was used to detect DNA of herpes simplex virus (HSV) in 38 samples of cerebrospinal fluid (CSF) obtained from 22 patients (7 children and 15 adults) 1–20 days after the onset of encephalitis. The results were best with amplification on the pellet of the CSF-extracted DNA and with analysis of the amplified products by dot-blotting (sensitivity, 100%). A highly significant difference was evident in the χ2 test when PCR was compared with specific antigen detection or antibody evaluation (n = 19; χ2 = 7; sensitivity = 100% vs. 63%) or with interferon α determination (n = 20; χ2 = 11; sensitivity = 95% vs. 42%). PCR was positive as early as 1 day after onset of disease and was often the first test to become positive. The detection of HSV DNA by PCR is the most specific, rapid, and sensitive tool for early diagnosis and therapeutic management of acute HSV encephalitis.