February 5, 1997

School-Based Clusters of Meningococcal Disease in the United StatesDescriptive Epidemiology and a Case-Control Analysis

Author Affiliations

From the Childhood and Respiratory Diseases Branch, Division of Bacterial and Mycotic Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Ga (Drs Zangwill, Schuchat, Riedo, Pinner, Koo, Reeves, and Wenger). Dr Zangwill is now with the Harbor-UCLA Medical Center, UCLA Center for Vaccine Research, UCLA School of Medicine, Los Angeles, Calif. Dr Riedo is now with the Department of Medicine, University of Washington Medical School, Seattle. Dr Pinner is now with the National Center for Infectious Diseases at CDC. Dr Koo is now with the Epidemiology Program Office at CDC. Dr Wenger is now with the World Health Organization, Geneva, Switzerland.

JAMA. 1997;277(5):389-395. doi:10.1001/jama.1997.03540290041030

Objective.  —To evaluate the epidemiologic features and risk factors for multiple cases of meningococcal disease in schools.

Design.  —Population-based prospective evaluation and case-control study of clusters of meningococcal disease that occurred in schools from January 1989 to June 1994.

Setting.  —Surveillance conducted through state health departments in the United States.

Main Outcome Measures.  —Descriptive epidemiology of school-based clusters of meningococcal disease and determinants of their occurrence.

Results.  —We identified 22 clusters of meningococcal disease in 15 states. The estimated incidence of secondary meningococcal disease among schoolchildren aged 5 to 18 years was 2.5 per 100 000 population, a relative risk of 2.3 (95% confidence interval [CI], 1.6-3.3). The median number of students per cluster was 2 (range, 2-4). Of 30 subsequent cases, 10 (33%) occurred 2 or fewer days after the index case, and 22 (73%) occurred 14 or fewer days after the index case. Among the 8 schools with 2 or more cases, 50% of the additional cases occurred 2 or more days after the second case. Secondary schools (grades 7 through 12) accounted for 15 (75%) of 20 cluster schools compared with 9 (45%) of 20 matched control schools (P<.05). In 16 (73%) of 22 clusters, interaction between case patients was noted. The index patient in cluster schools was more likely than the controls to have participated in a school-based group activity 14 or fewer days before illness (matched odds ratio, 7.0; 95% CI, 0.9-57).

Conclusions.  —Three quarters of the school clusters occurred in secondary schools, with over 70% of subsequent cases occurring within 2 weeks of the index case. Rapid initiation of a chemoprophylaxis program after 2 cases of meningococcal disease in a school would have potentially prevented 50% of subsequent cases in the clusters described.