HERPES-ENCEPHALITIS IS A DISEASE OF MIDDLE-AGED AND ELDERLY PEOPLE - POLYMERASE CHAIN-REACTION FOR DETECTION OF HERPES-SIMPLEX VIRUS IN THECSF OF 516 PATIENTS WITH ENCEPHALITIS

Objective-To assess the diagnostic potential of the polymerase chain r eaction (PCR) in herpes simplex virus (HSV) encephalitis. Methods-Samp les of CSF from 516 patients with encephalitis were studied for HSV-DN A by PCR. Results-Samples taken one to 29 days from the onset of sympt oms from 38 patients (7.4%) were positive, 32 (6.2%) for HSV-1 and six (1.2%) for HSV-2. At follow up, eight of 28 patients studied were sti ll HSV-PCR positive. A diagnostic serum:CSF antibody ratio to HSV but not to other viruses was detected in 25 of the 38 HSV-PCR positive pat ients thus supporting the initial PCR findings. Patients positive by H SV-PCR were concentrated in the age group greater than or equal to 40 years, and especially in patients aged 60-64 years, of whom nine of 24 (37.5%) were positive. The HSV-PCR was negative in all other patients with encephalitis of known or unknown aetiology. This group included 34 patients with a diagnostic serum:CSF antibody ratio to other viruse s. A dual infection, HSV and another microbe, was considered possible in seven patients. Conclusions-The HSV-PCR is a rapid and useful diagn ostic method during the early phase of encephalitis. It may be useful in monitoring the efficacy of treatment and allowing the recognition o f new features in the appearance of herpes encephalitis. The HSV-PCR t est and antibody determinations from serum and CSF are complementary m ethods, which should both be applied in pursuit of clinical laboratory diagnosis of these conditions.