Mumps Cases & Outbreaks
Mumps is no longer very common in the United States. Each year, on average, a few hundred people in the U.S. are reported to have the disease. Before the U.S. mumps vaccination program started in 1967, about 186,000 cases were reported each year. Since the pre-vaccine era, there has been a more than 99% decrease in mumps cases in the United States.
In some years, there are more cases of mumps than usual because of outbreaks. Mumps outbreaks can occur any time of year but often occur in winter and spring. A major factor contributing to outbreaks is being in a crowded environment, such as attending the same class, playing on the same sports team, or living in a dormitory with a person who has mumps.
Although the measles-mumps-rubella (MMR) vaccine is very effective, protection against mumps is not complete. Two doses of measles-mumps-rubella (MMR) vaccine are 88% effective at protecting against mumps; one dose is 78% effective. Outbreaks can still occur in highly vaccinated U.S. communities, particularly in close-contact settings. In recent years, outbreaks have occurred in schools, colleges, and camps. However, high vaccination coverage helps limit the size, duration, and spread of mumps outbreaks.
2014 Mumps Outbreaks
As of April 4, 2014, mumps outbreaks have been reported in:
Past Mumps Outbreaks
- In 2011-2013, there were several smaller mumps outbreaks reported on college campuses in California, Virginia, and Maryland. However, these all had limited spread, and national case counts for these years were at usual levels (several hundred cases per year).
- In 2009- 2010, two large outbreaks occurred.
- One outbreak involved about 3,000 people and mostly affected high school-aged students who were part of an insular religious community in New York City and attended schools in which they had very close contact. The index case-patient was an 11-year-old member of the religious community who had returned from the United Kingdom where a large mumps outbreak was occurring.
- The second outbreak involved about 500 people, mostly school-aged children, in the U.S. Territory of Guam.
- In 2007-2008, the number of reported cases returned to usual levels (several hundred cases per year), and outbreaks involved fewer than 20 cases.
- In 2006, the United States experienced a multi-state mumps outbreak involving more than 6,500 reported cases. This resurgence predominantly affected college-aged students living in the Midwest, with outbreaks occurring on many different Midwestern college campuses.
For General Public
- Outbreak-Related Questions and Answers for Patients
- Fast Facts About Mumps
Fact sheet with information about symptoms, vaccination, complications, and transmission.
For Health Professionals
- Outbreak-Related Questions and Answers for Healthcare Providers
- Manual for the Surveillance of Vaccine-Preventable Diseases, Chapter 9: Mumps
For clinical information about mumps outbreaks, please see the Mumps Outbreak Investigation and Outbreak Control section of the VPD Surveillance Manual.
- Laboratory Testing for Mumps Infection
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