MEASLES — UNITED STATES, JANUARY 1–AUGUST 24, 2013

Tuesday, 14th of January 2014

[source]Morbidity and Mortality Weekly Report (MMWR)[|source]

Although measles elimination was declared in the United States in 2000, importation of measles cases continues to occur. In this article, CDC evaluated measles cases reported by 16 states during January 1–August 24, 2013. The authors documented that a) most measles cases were in persons who were unvaccinated or had unknown vaccination status; b) Forty-two measles virus importations were reported, and c) 50% of measles importations were from the World Health Organization (WHO) European Region.  More details and implications for measles elimination are available at:  http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6236a2.htm

Editorial Note

Measles elimination has been maintained in the United States since it was declared in 2000. However, an estimated 20 million cases of measles occur each year worldwide, and cases continue to be imported into the United States. The increase in measles cases in the United States in 2013 serves as a reminder that imported measles cases can result in large outbreaks, particularly if introduced into areas with pockets of unvaccinated persons.

During 2013, nearly two thirds of the cases came from three outbreaks. In these outbreaks, transmission occurred after introduction of measles into communities with pockets of persons unvaccinated because of philosophical or religious beliefs. This allowed for spread to occur, mainly in households and community gatherings, before public health interventions could be implemented. Despite progress in global measles control and elimination, measles importations are likely to continue posing risks of measles outbreaks in unvaccinated communities. Maintaining high MMR vaccination coverage is essential to prevent measles outbreaks and sustain measles elimination in the United States.

To date in 2013, 23 measles importations have been reported by U.S. residents, most of whom were aged ≥6 months and unvaccinated. The source of imported cases continues to be most often the WHO European Region, a popular destination for U.S. travellers and an area where measles continues to circulate. All persons aged ≥6 months without evidence of measles immunity who travel outside the United States should be vaccinated before travel with 1 dose of MMR vaccine for infants aged 6–11 months and 2 doses for persons aged ≥12 months, at least 28 days apart. Routine MMR vaccination is recommended for all children at age 12–15 months, with a second dose at age 4–6 years. Two doses of MMR vaccine are also recommended for health-care personnel and students attending post–high school educational institutions, unless they have other evidence of immunity. Other adults without evidence of measles immunity should receive 1 dose of MMR vaccine. Health-care providers should encourage timely vaccination of all eligible patients and should remind parents who plan to travel internationally with children of the increased risk for measles and the importance of vaccination.

Patients with measles often seek medical care; therefore, health-care providers should maintain a high awareness of measles and suspect measles in persons who have a febrile rash illness and clinically compatible symptoms and who have recently travelled abroad or have had contact with travellers. Providers should implement isolation precautions immediately, collect an appropriate laboratory specimen, and promptly report suspected measles case to their local health department. Early reporting and rapid control efforts by states and local public health agencies are essential to limit the spread of disease. Timely response plays an important role in limiting the size of outbreaks and preventing spread of measles, even in communities with large numbers of unvaccinated persons.

High MMR vaccine coverage in the United States (91% among children aged 19–35 months) limits the size of measles outbreaks; however, some states have coverage levels <90%. Additionally, unvaccinated children tend to cluster geographically and socially, increasing the risk for outbreaks. Increases in the proportion of persons declining vaccination for themselves or their children might lead to large-scale and sustained outbreaks, threatening the elimination of measles in the United States. Maintenance of high, 2-dose MMR vaccine coverage, early detection of cases, and rapid public health response to a case are the key factors that will lead to sustained elimination, despite the continued importation of cases into the United States.