Simultaneous serum and CSF antibodies in herpes simplex virus encephalitis.

Serial concomitant paired sera (S) and CSF were taken from eight patients with biopsy-proved herpes simplex virus encephalitis (HSVE). These specimen pairs were compared with 28 others from patients with various neurologic conditions. Before and after reduction with 2-mercaptoethanol, a ratio of S/CSF antibody titers of less than or equal to 20 with either the passive hemagglutinating (PHA) or immune adherence hemagglutinating (IAHA) antibody tests occurred in every patient with HSVE. Diagnostic S/CSF ratios were noted in three patients before biopsy of the brain and in four patients by the tenth day of neurologic disease. Among control subjects, a ratio of S/CSF titers greater than 20 was observed in all but four patients. Each of the latter patients had neurologic diagnoses easily distinguishable from HSVE. The PHA or IAHA S/CSF ratio offers a rapid, reliable method for the diagnosis of HSVE (P less than .001).