Sero-epidemiology of Neisseria meningitidis infections in parts of Eastern Nigeria.

The prevalence of antibodies to meningococci in the Nsukka area, East Central Nigeria, was studied by the indirect hemagglutination test employing tanned chicken erythrocytes. Of the 1332 apparently healthy persons, whose sera were tested, 982 samples (73.8%) were positive at 1:8 dilution of the sera. Fifty-six per cent of the population had antibodies to Group B, followed by 13% of Group C and 5% to Group A. Twenty-five sera from patients with meningococcal infections, from whom Group B meningococci were isolated, 100% were positive. Percentage reactivity in the 2-5-year age group was low (15%), whereas it increased rapidly from 78% (6-10-year group) to 95% (31 years and above).