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Current Trends Measles -- United States, First 17 Weeks, 1984

From January 1, 1984, to May 5, 1984 (the year's first 17 reporting weeks), a provisional total of 968 measles cases was reported in the United States. This is a 46.2% increase from the same period in 1983 (Figure 1).

Seventy-nine (2.5%) of the nation's 3,138 counties reported measles in the 17-week period, compared with 56 (1.8%) in the same period of 1983. Of the 968 cases, 831 (85.8%) were part of 14 chains of transmission. The three largest chains--in California, Michigan, and Texas--accounted for 56.2% (544/968) of the total cases (Figure 2). The chains in California and Michigan primarily involved junior and senior high-school students. The Texas outbreak is still under investigation.

A provisional total of 42 international importations was reported during the first 17 weeks of 1984, an average of 2.5 cases per week, compared with 95 (5.6 cases per week) in the same period in 1983. Reported by Div of Immunization, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: Chains of measles transmission in 1984 have been concentrated primarily among school-aged children. This is a change from 1983, when most documented transmission occurred outside primary and secondary schools (1). While lack of enforcement of immunization laws factored in some of the outbreaks, some of the 1984 school-based chains of transmission occurred in schools with high immunization levels (in excess of 95%). The reasons for these outbreaks are not yet clear and are currently under investigation. Nevertheless, county-specific data indicate that most areas of the country are still free of measles.

The observation that measles outbreaks sometimes can occur among the small proportion of vaccine failures demonstrates the importance of strict adherence to immunization requirements to minimize the remaining number of susceptibles. Whenever students are admitted to school provisionally, their immunization records should be completed promptly. Noncompliant students should be excluded from school attendance. Experience has demonstrated that strict exclusion of such students results in high immunization levels, with minimal delay and minimal disruption of routine activities (2). School officials should maintain a permanent register of students who are not vaccinated because of medical, religious, or philosophic exemption, to allow rapid identification and exclusion of such students during an outbreak.


  1. CDC. Measles--United States, 1983. MMWR 1984;33:105-8.

  2. CDC. Measles--Florida, 1981. MMWR 1981;30:593-6.

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