School-based clusters of meningococcal disease in the United States. Descriptive epidemiology and a case-control analysis.
OBJECTIVE
To evaluate the epidemiologic features and risk factors for multiple cases of meningococcal disease in schools.


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


METHODS
Surveillance conducted through state health departments in the United States.


METHODS
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 100000 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.
Zangwill
K M
KM
Childhood and Respiratory Diseases Branch, Division of Bacterial and Mycotic Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, GA 30333, USA.
Schuchat
A
A
Riedo
F X
FX
Pinner
R W
RW
Koo
D T
DT
Reeves
M W
MW
Wenger
J D
JD
D000041:Absenteeism; D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D006801:Humans; D016015:Logistic Models; D008589:Meningococcal Infections / Q000453:epidemiology*; D009345:Neisseria meningitidis / Q000145:classification / Q000302:isolation & purification; D011446:Prospective Studies; D012307:Risk Factors; D012574:Schools / Q000706:statistics & numerical data; D012703:Serotyping; D014481:United States / Q000453:epidemiology