The role of young children in a community-wide outbreak of hepatitis A.

An Hasidic Jewish community has experienced recurrent hepatitis A outbreaks since 1980. To assess risk factors for illness during a 1985-6 outbreak, the authors reviewed case records and randomly selected 93 households for an interview and serologic survey. In the outbreak, 117 cases of hepatitis A were identified, with the highest attack rate (4.2%) among 3-5 year olds. Among the survey households, the presence of 3-5 year olds was the only risk factor that increased a household's risk of hepatitis A (indeterminant relative risk, P = 0.02). Furthermore, case households from the outbreak were more likely to have 3-5 years olds than were control households from the survey (odds ratio = 16.4, P < 0.001). Children 3-5 years old were more likely to have hepatitis A and may have been the most frequent transmitters of hepatitis A in this community. Hepatitis A vaccination of 3-5 year olds can protect this age group and might prevent future outbreaks in the community.