Measles--United States, 2004.

Measles is a highly infectious, acute viral illness that can cause severe pneumonia, diarrhea, encephalitis, and death. During 2004, a total of 37 cases (incidence: <1 case per million population) was reported to CDC by local and state health departments, the lowest number of measles cases ever reported in 1 year in the United States and a decrease of 16% from the previous low of 44 cases in 2002. This report describes the epidemiology of measles in the United States in 2004, documenting the absence of endemic measles and the continued risk for internationally imported measles cases that can result in indigenous transmission.