From January 1 to March 20, 2015, 178 people from 17 states and the District of Columbia were reported to have measles [AZ (7), CA (120), CO (1), DC (2), DE (1), GA (1), IL (15), MI (1), MN (1), NE (2), NJ (2), NY (3), NV (9), PA (1), SD (2) TX (1), UT (2), WA (7)]†. Most of these cases [131 cases (74%)] are part of a large, ongoing multi-state outbreak linked to an amusement park in California).

The United States experienced a record number of measles cases during 2014, with 644 cases from 27 states reported to CDC’s National Center for Immunization and Respiratory Diseases (NCIRD). This is the greatest number of cases since measles elimination was documented in the U.S. in 2000.

• The majority of people who got measles were unvaccinated.
• Measles is still common in many parts of the world including some countries in Europe, Asia, the Pacific, and Africa.
• Travelers with measles continue to bring the disease into the U.S.
• Measles can spread when it reaches a community in the U.S. where groups of people are unvaccinated.

Measles Outbreaks

U.S. Multi-state Measles Outbreak 2014—2015

The United States is currently experiencing a large, multi-state outbreak of measles linked to an amusement park in California.
(http://www.cdc.gov/measles/multi-state-outbreak.html)

Outbreaks in countries to which Americans often travel can directly contribute to an increase in measles cases in the U.S.

Reasons for an increase in cases some years:

• 2015: The United States is currently experiencing a large, multi-state measles outbreak linked to an amusement park in California(http://www.cdc.gov/measles/multi-state-outbreak.html). Three other unrelated outbreaks are occurring in Illinois,  Nevada, and Washington respectively.
• 2014: The U.S. experienced 23 measles outbreaks in 2014, including one large outbreak of 383 cases, occurring primarily among unvaccinated Amish communities in Ohio. Many of the cases in the U.S. in 2014 were associated with cases brought in from the Philippines, which experienced a large measles outbreak. For more information see the Measles in the Philippines Travelers’ Health Notice.
• 2013: The U.S. experienced 11 outbreaks in 2013, three of which had more than 20 cases, including an outbreak with 58 cases. For more information see Measles — United States, January 1-August 24, 2013.
• 2011: In 2011, more than 30 countries in the WHO European Region reported an increase in measles, and France was experiencing a large outbreak. Most of the cases that were brought to the U.S. in 2011 came from France. For more information see Measles — United States, January-May 20, 2011.
• 2008: The increase in cases in 2008 was the result of spread in communities with groups of unvaccinated people. The U.S. experienced several outbreaks in 2008 including three large outbreaks. For more information see Update: Measles — United States, January–July 2008.

See also: The Surveillance Manual chapter on measles that describes case investigation, outbreak investigation, and outbreak control for additional information.