International Importation of Measles Virus—United States, 1993–;2001

To determine trends in international importations of measles, data from the National Notifiable Diseases Surveillance System were analyzed. Of the 2632 measles cases reported between 1993 and 2001, 449 cases (17%) were internationally imported. An additional 186 cases (7%) resulted from spread of measles virus from these imported cases, and 388 cases (15%) had virological evidence of importation. The number of imported cases averaged 50 per year (range, 26-79 cases). The proportion of cases imported increased from an average of 14% in 1993-1996 to an average of 35% in 1997-2001. Imported measles cases were acquired in 63 countries, with 6 countries (Japan, Germany, China, the Philippines, Italy, and the United Kingdom) accounting for 44% of all imported cases. Further reduction of measles in the United States requires international cooperation and improved global surveillance and control of measles.