Meningococcal disease at the University of Southampton: outbreak investigation

In October 1997, an outbreak of meningococcal disease occurred at the Unive rsity of Southampton. All six cases were first year students living in hall s of residence. Microbiological characterization of case and carrier strain s, case interviews, and a meningococcal carriage prevalence survey were use d to investigate the outbreak. Five cases were due to serogroup C strains, one case was unconfirmed. Serotyping did not distinguish between the strain s but gene sequencing permitted identification of two distinct strains in t he outbreak. Although none of the cases was known to each other, three had attended the same nightclub one evening 3-4 days before illness. Meningococ cal carriage rates in undergraduates were within the range expected (147/58 7, 25%), but no carriers of outbreak strains were identified in this sample . The findings suggest that in communities with a high degree of social int eraction, the introduction of highly virulent meningococcal strains may res ult in enhanced transmission with clustering of cases.