The incidence and aetiology of central nervous system infections in Helsinki in 1980.

The aetiology of central nervous system infections was surveyed in a study at Aurora Hospital, Helsinki, in 1980. Of the 146 patients with central nervous system infections, 113 had aseptic meningitis, 23 bacterial and one tuberculous meningitis, and nine meningoencephalitis or encephalitis. The probable aetiology of aseptic meningitis was established in 67% of the 106 patients properly tested, the commonest agents being mumps (27%), Coxsackie (24%) and ECHO (9%) viruses. Haemophilus influenza type b was the most frequent cause of bacterial meningitis (39%), occurring solely among infants and young children. There were no cases due to Neisseria meningitidis group A, which used earlier to be epidemic in Finland. The incidences of aseptic, bacterial and tuberculous meningitis in Helsinki in 1980 (based on a total of 174 patients treated in the three hospitals admitting patients with central nervous system infections) were 26.7, 5.2 and 0.2 cases per 100,100 annually, and those of encephalitides and myelitis 3.5 and 0.6 cases per 100,000 annually.