Clusters of meningococcal disease in France (1987-1988).

We analyzed 814 cases of meningococcal disease notified in 1987 and 1988 to the Ministry of Health. Data were obtained by report forms including informations about possible additional cases among contacts. Coprimary cases (occurring within 24 hours after the index case) and secondary cases (occurring more than 24 hours after index case) were all reviewed. Twenty eight clusters of meningococcal disease were identified involving 65 cases (8% of total cases). Twelve of the 814 cases (1.5%) were coprimary cases of an index case and 25 (3%) were secondary cases. The secondary attack rate was 530/100,000 among household contacts and 31/100,000 among school contacts. Seventy two per cent of the secondary cases occurred in the first week after index case. Thirty-eight percent of the secondary cases occurred in the 15-20 age group as opposed to 15% of single cases. Serogroup A was more often found in coprimary (33%) and secondary cases (17%) than in single cases (6%). In France, prophylaxis of secondary cases is administered to the classroom contacts of a case of meningococcal infection but is not required for the entire school except under epidemic conditions.