A college outbreak of group C meningococcal infection: how widely should investigation and prophylaxis extend?

Neisseria meningitidis group C type 2b, P1.2, P1.5 caused an outbreak of four cases, two of whom were members of an agricultural college in Devon, and two outside contacts of students who were documented carriers of the outbreak strain. The identification of the outbreak was made more difficult by the fact that none of the three cases first linked with the college was culture positive and indeed only one of these was actually a member of the college. Carriage of the outbreak strain was significantly associated with residence in college and enrollment on one particular course. The question was raised of whether in outbreaks of this type control measures should be extended beyond the confines of the affected institution.