Central nervous system infections in the rainforest zone of Nigeria.

Objectives: To ascertain incidence rates of central nervous system infections and provide information for health care planners.
Design: A two-stage screening through supervised case referrals and diagnostic evaluation at referral centre to establish a register of CNS infections.
Setting: A rural community in the rainforest zone of Nigeria with land area of 186500 m2, average daily temperature of 28 degrees C, annual rainfall of 2080 mm, adult population of 109851 and served by 26 primary, three secondary and twelve comprehensive care facilities. More than two per cent of the populations live in waterlogged areas.
Subjects: Adults aged sixteen years and above, constituting incident cases of CNS infections.
Main Outcome Measures: Incident CNS infections per 100,000 populations averaged over a two year observational period.
Results: Incidence rates were 3.6, 4.1, 2.3, 09, 1.8, 0.9 for acute bacterial meningitis, aseptic meningitis, rabies encephalitis, non-rabies encephalitis, tuberculous meningitis and chronic non-tuberculous meningoencephalitis, respectively. Syphilitic neuroarthropathy had 0.46.
Conclusions: Mortality from acute pyogenic meningitis and tuberculous meningitis remained distressingly high. Aseptic meningitis had the highest incidence rate, yet remained inadequately emphasised. Rabies encephalitis was the third commonest cause of CNS infection in the area.