English summary: AETIOLOGY OF ASEPTIC MENINGITIS AND ENCEPHALITIS IN ADULT PATIENTS

Objective

To investigate the aetiology of aseptic meningitis and encephalitis in an adult population using modern microbiological methods.

Methods

Consecutive patients (aged >= 16 years) with aseptic meningitis or encephalitis treated in Turku University Hospital, Finland, during 1999-2003 were included in the study. Microbiological tests were performed, including CSF PCR tests for enteroviruses, herpes simplex virus 1 (HSV-1), HSV-2 and varicella-zoster virus (VZV), as well as serum and CSF antibody analysis for these viruses. Antibody testing was also performed for other pathogens commonly involved in neurological infections. Virus culture was performed on CSF, fecal and throat swab specimens.

Results

The aetiology was identified in 95 of 144 (66%) patients with aseptic meningitis. Enteroviruses were the major causative agents (26%), followed by HSV-2 (17% of all, 25% of females) and VZV (8%). The aetiology was identified in 15 of 42 (36%) patients with encephalitis, VZV (12%), HSV-1 (9%) and tick-borne encephalitis virus (9%) being the most commonly involved pathogens. Etiological diagnosis was achieved by PCR in 43% of the patients with meningitis and in 17% of those with encephalitis.

Conclusions

Enteroviruses and HSV-2 are the leading causes of adult aseptic meningitis, and PCR is often essential to reveal the causative diagnosis. However, in most cases of encephalitis the aetiology remains undefined.