Surveillance of cases of meningococcal disease associated with military recruits studied for meningococcal carriage.

Through a 14-months extended surveillance of meningococcal disease in Denmark, all 322 notified cases were investigated for possible connection with a military camp where 3 cohorts of recruits (n = 1069) were studied prospectively for meningococcal carriage. One case occurred in a recruit who was a constant non-carrier during the preceding 3 months. The invasive Neisseria meningitidis B:1:P1.1,7 strain was isolated from the pharynx only in 3 out of 17 room-mates (18%); the strains were identical as assessed by genotyping (PFGE and ribotyping). Two civilian cases outside the camp had direct contact with 2 recruits, but neither these 2 nor other recruits in the relevant divisions carried the invasive strains on any occasion. Six civilian cases had marginal relationship with the camp, but no contact with the recruits. In conclusion, pheno- and genotyping concordantly demonstrated a high carriage rate of the invasive strain among the room-mates to a recruit with meningococcal disease. Transmission to the patient most likely occurred shortly before onset of illness. The extended surveillance did, however, not identify any unexpected epidemiological links and restriction of antibiotic chemoprophylaxis to household/sleeping/kissing contacts in sporadic cases of meningococcal disease seems appropriate and relevant.