Two measles outbreaks after importation - Utah, March-June 2011.

Before licensure of a measles vaccine in 1963, more than 500,000 measles cases on average were reported in the United States each year during 1951-1962. By 1993, through measles vaccination and control efforts, only 312 cases were reported nationwide. In 2000, the last year in which an outbreak had occurred in Utah, measles was declared "not endemic in the United States," but measles importations continue to occur, leading to outbreaks, especially among unvaccinated persons. Many U.S. health-care personnel have never seen a measles patient, which might hamper diagnosis and delay reporting. During March-June 2011, local health departments collaborated with the state health department in Utah to investigate two measles outbreaks comprising 13 confirmed cases. The first outbreak, with seven confirmed cases, was associated with an unvaccinated U.S. resident who traveled internationally; the second, with six confirmed cases, had an undetermined source. The genotype D4 sequences obtained from these two outbreaks differed by a single nucleotide, suggesting two separate importations. Health-care providers should remind their patients of the importance of being current with measles, mumps, and rubella (MMR) vaccination; this is especially important before international travel. Measles should be considered in the differential diagnosis of febrile rash illness, especially in unvaccinated persons with recent international travel. Reporting a confirmed or suspected case immediately to public health authorities is critical to limit the spread of measles.