Neisseria meningitidis strains isolated in CSR from cerebrospinal fluid: preepidemic shift in serogroup and serotype distribution?

Abstract

Antigenic properties of N. meningitidis strains isolated from CSF in CSR were surveyed. Capsular antigens (serogroups) were tested from 1970, noncapsular antigens (serotypes) from 1975. Results up to the end of 1982 are presented. In 1980 shifts were encountered in the distribution of both capsular and noncapsular antigens. Serogroups. Group B predominated throughout the surveillance period, but from 1980 this predominance was significantly lower. Group C was the second most frequent throughout the observed period, but its frequency rose significantly from 1980 and stayed high. Group A was the third in frequency all the time, its relative prevalence increased (but not significantly) from 1980. Serotypes. Serotype 2 predominated during the whole period, but its predominance rose significantly from 1980. Serotype 4 was second in frequency, but from 1980 its frequency also increased significantly. Serotypes other than 2 or 4 decreased significantly in frequency and variability from 1980, also nontypable strains decreased significantly from 1980. Changes in the distribution of the capsular and noncapsular antigens on N. meningitidis strains from CSR are characteristic of epidemic situation. The present finding is all the more serious because it comes in a context of rising meningococcal morbidity and a shift in the morbidity into older age groups.