| Disneyland measles outbreak | |
|---|---|
 Young boy with measles | |
| Disease | Measles |
| Virus strain | Measles morbillivirus |
| Location | United States, Mexico, Canada |
| First outbreak | December 2014 |
| First reported | January 5, 2015 |
| Index case | Unidentified |
| Confirmed cases |
|
| Hospitalized cases | 10–20% of affected |
Deaths | None |
| Vaccinations | Measles vaccine |
The Disneyland measles outbreak began at the Disneyland Resort, California, in December 2014, and spread to seven states in the United States, Mexico, and Canada, before it was declared over in mid-April 2015.
The first case of measles was reported on January 5, 2015, in an unvaccinated 11-year-old Californian resident. Between December 2014 and March 2015, 131 Californians were infected, with almost 90% of cases occurring in southern California. Linked to the California cases were 16 cases in six other US states, 159 cases in a religious group in Québec, Canada, and one case in Mexico. Almost all the Canadian cases were unvaccinated. The source of the initial Disney theme park exposure was not identified, but specimens from several cases matched with the recent measles outbreak in the Philippines.
It triggered an international debate on vaccine hesitancy, particularly as it had spread to people who intentionally declined the vaccine and put vulnerable people who could not have the vaccine at risk. The outbreak prompted the California Senate Bill 277, laws that reverted the California personal belief vaccine exemption. Conclusions following examination of the outbreak pointed to undervaccination as a key cause.