ACUTE VIRAL ENCEPHALITIS IN ADULTS - A PROSPECTIVE-STUDY

We have prospectively studied 27 adult patients attending the Departme nt of Infectious Diseases, Goteborg, Sweden, between October 1992 and October 1996 with a diagnosis of acute viral encephalitis. In addition to cerebrospinal fluid (CSF) virus isolations and antibody analyses a gainst herpes simplex virus, cytomegalovirus, varicella tester virus, Epstein-Barr virus (EBV), enterovirus, adenovirus, tick-borne encephal itis virus, and mycoplasma, polymerase chain reaction test (PCR) to 5 viruses from the family of human herpes viridae, and to adenovirus as well as to enterovirus mere analysed in CSF, 10 patients had herpes si mplex virus type-1 (HSV-1), 1 had varicella tester virus, 1 had tick-b orne encephalitis, and 2 had Influenza A infections. In 13 patients th e aetiology remained unclear, Eight patients with HSV-1 encephalitis a nd clinical symptoms for 2-11 d before admission were PCR-positive, wh ile 2 patients with a less than or equal to 2 d history of disease wer e negative for HSV-1 DNA on admission, These 2 patients became positiv e for HSV-1 DNA in CSF samples taken 4 d later in 1 case and 7 d later in the other, In 4 patients with HSV-1 encephalitis, in 1 patient wit h Influenza A complicated by encephalitis, and in 1 patient with encep halitis of unknown origin EBV DNA was found in CSF samples during the study. The clinical significance of these findings is unclear. The stu dy shows that HSV-I was the most common etiological agent in patients with viral encephalitis in the Goteborg area. In spite of improved dia gnostic procedures, a large proportion of patients with symptoms and l aboratory findings compatible with viral encephalitis still have an un clear aetiology.