In the week following a carnival during 19–24 February 1998, an outbreak of meningococcal
disease occurred in a rural German county. The available isolates belonged to phenotype
C[ratio ]2a[ratio ]P1.2,5 and were clonally related by pulsed-field gel electrophoresis. A case-control study
was done to identify risk factors for the outbreak and to define possible vaccination target
groups. Five persons aged 13–16 years who fell ill during 24–27 February were included in the
study. Four of 5 cases and 10 of 32 controls visited local discotheques (OR = 8·8; P = 0·06).
Cases also visited discotheques more frequently than controls (χ2 for trend, P = 0·0002).
Multiple discotheques during the carnival may have been predominant locations of
transmission in this outbreak. Because this risk factor was limited in time, a mass community
vaccination campaign was not initiated.