Epidemic measles in Chicago in 1983. Sustained transmission in the preschool population

M. Bennish, P. M. Arnow, M. O. Beem and S. Doveikis

We evaluated epidemiologic features of 54 patients with measles seen at Wyler Children's Hospital during a 1983 measles epidemic in Chicago. Forty-one (76%) were less than 5 years old, and 23 (43%) were less than 16 months old. We found evidence of a low rate of measles immunity in preschool-aged children of immunization age immediately before the epidemic; only 62% of 173 emergency room patients this age had antibody on enzyme-linked immunosorbent assay. These observations, together with failure of school-based control measures to significantly affect the observed course of the epidemic, indicate that the preschool population sustained the epidemic. Unimmunized preschool-aged children are important in the current epidemiology of measles, and improved immunization strategies are needed to control measles in this population in Chicago and perhaps other cities.