Seven cases of measles have been confirmed in the state of California, according to the California Department of Public Health. Two additional cases were reported in the state of Utah.
The Californians, including six children, are from Riverside, Orange, San Diego and Alameda counties, as well as the city of Pasadena. Three people have been hospitalized.
All of the 12 people were visiting Disneyland or the Disney California Adventure theme park between December 15 and December 20. Health officials claim that an infected park-goer might have spread the virus.
“We are working with the health department to provide any information and assistance we can," said Dr. Pamela Hymel, the chief medical officer at Walt Disney Parks and Resorts.
A Disneyland spokesperson said further questions will be directed to the Department of Public Health.
Health officials say Disneyland and other theme parks are international attractions with visitors from all over the world, including areas where the measles is an epidemic.