Meningococcal disease in Belgium. Secondary attack rate among household, day-care nursery and pre-elementary school contacts.

During a recrudescence of meningococcal disease mainly due to serogroup B, 1913 notified cases were investigated in Belgium from 1971 to 1976. From 1971 to 1973, 76 secondary cases were reported out of a total of 1455 cases (5.2 per cent); and from 1974 to 1976, nine secondary cases were reported of a total of 458 cases (2.