Risk factors associated with a school-related outbreak of serogroup C meningococcal disease

An outbreak of Neisseria meningitidis sero-group C disease occurred in four eighth grade students and in a younger sibling of another eighth grade student attending an intermediate school (seventh and eighth grades) in Santa Clara County, CA. Four cases had onset within 3 days in January, 1989, with the fifth case occurring approximately 10 days later. A case-control study was performed to determine risk factors associated with serogroup C meningococcal infection (disease or carriage) in this eighth grade class. Students were more likely to be infected if they had had a preceding viral-like respiratory illness characterized by fever (odds ratio (OR) 5.3, P = 0.03) or cough (OR 5.1, P = 0.048). A ski trip (OR 6.3, P = 0.01) and a poster-making session for a school dance (OR 3.7, P = 0.08) were identified as possible settings for a common exposure. Spending time with two specific students during lunchtime or outside of school was associated with an increased risk of infection (OR 7.0, P = 0.054; OR 5.8, P = 0.04).