Abstract

A prospective study of the nasopharyngeal carriage of sulphonamide resistant Neisseria meningitidis, group B, type 15 P1.16, was undertaken after a cluster of four cases of meningococcal infections had occurred, two of which were fatal, during a three year period among children attending an inner London primary school. Throughout the year of the study the overall carriage and acquisition rates of meningococci were less than 6% and 1%, respectively, and were no different from those of control children of similar age and ethnic origin from another school. The outbreak strain was isolated from three children in the study school, however, but from none in the control school. A comparison of bactericidal activity in serum against the outbreak strain in children from selected classes in each school showed that there was no lack of bactericidal activity to this strain in the study school. The low prevalence of strain specific bactericidal activity in sera taken from classroom contacts of carriers, combined with the low carriage and acquisition rats, suggested a pattern of prolonged colonisation with infrequent transmission of the organism from child to child, and was consistent with the pattern of cases seen in the school.