Trends in importation of measles to the United States, 1986-1994.

OBJECTIVES

To describe patterns among imported measles cases to the United States.

DESIGN

Descriptive analysis of national case-based surveillance data on measles cases.

SETTING

United States in the period 1986 through 1994.

PATIENTS

All reported confirmed cases of measles.

MAIN OUTCOME MEASURES

Demographic variables, immunization history, country of exposure, and reporting state.

RESULTS

The number of reported imported cases of measles to the United States has dropped from an average of 99 cases annually in 1986 through 1988 and 190 cases in 1989 through 1991 to 61 cases in 1992 through 1994. Since 1990, the number of imported cases originating in Latin America declined by 98%, despite continued increase in the number of travelers to this region; cases from other regions remained relatively constant. This decrease paralleled the rapid decrease in measles incidence in the Western Hemisphere associated with national measles elimination programs. Most imported cases occurred among children, although 22% of cases occurred among young adults. Rates of measles cases per 1 million travelers are higher among non-US citizens than among US citizens.

CONCLUSIONS

The sharp decline in importations into the United States from Latin America since 1991 provides evidence of the success of measles control efforts undertaken there. The decrease in imported cases has been associated with a decline in total measles cases in the United States. Sustained elimination of measles in the United States will require improved measles control in other countries in addition to a high level of population immunity.