Imported measles in the United States.

In the period 1980-1981, two hundred nine imported measles cases were reported in the United States. These cases represent 1.3% of the total of 16,630 cases of measles reported to the Centers for Disease Control (CDC) during that period. An average of two imported measles cases were reported each week. The travelers with imported measles were United States citizens and foreign nationals who arrived from 47 different countries throughout the world. However, returning United States citizens have accounted for a rising proportion of imported measles cases. Approximately half (49.3%) of the imported cases were reported by four areas: California, New York State exclusive of New York City, New York City, and Florida. Seven measles outbreaks occurring following importations during the two-year period were identified. In addition to 114 imported measles cases reported to the CDC in 1981, 437 measles cases were reported to be caused directly or indirectly by those importations. The actual number of import-associated cases may have been considerably higher. Imported measles and associated cases together accounted for at least 17% (551/3,124) of reported measles cases in 1981.