Screening for possible failure of herpes simplex virus PCR in cerebrospinal fluid for the diagnosis of herpes simplex encephalitis

The objectives of this study were to evaluate the reliability of herpes sim plex virus (HSV) PCR testing in cerebrospinal fluid (CSF) for the detection of herpes simplex encephalitis. This was done by examining retrospectively the clinical follow-up of a large group of patients tested routinely by HS V-PCR. In addition, an attempt was made to assess the incidence of herpes s implex encephalitis in a central European population. CSF samples from 1,42 7 patients from all Vienna hospitals were submitted for HSV-PCR testing dur ing a period of 4 years and 8 months. Herpes simplex encephalitis was detec ted by PCR in 12 cases and by serological methods in one additional patient . Retrospective analysis of the course of disease, which was possible in 79 9 PCR-negative patients, led to the identification of three additional case s in which herpes simplex encephalitis appears to have occurred despite neg ative PCR results. Failure of the PCR in these patients is most likely due to the time of obtaining CSF during the course of disease. A high specifici ty of the assay was demonstrated by the lack of false positive results in a ny of the 708 cases in which other causes for the neurological symptoms had been identified in the follow-up, The incidence of herpes simplex encephal itis in the population of Vienna was between 1 case! 469,000-577,000 indivi duals/year. The highest annual incidence was detected in the age group betw een 3 months and 3 years, which, however, could not be confirmed statistica lly. J. Med. Virol. 64-531-536, 2001. (C) 2001 Wiley-Liss, Inc.