Disney measles is the name being given to at least nine cases of the disease that were contracted by visitors to the theme parks in December 2014. Seven people in California have been diagnosed with the illness, along with two patients in Utah. Three more patients in the Golden State are believed to be suffering from the disease as well.

All those who contracted measles visited Disneyland in Anaheim, California, or Disney California Adventure between December 15 and 20, 2014. The youngest patient in California is eight months old, and the oldest is 21 years of age.

Six of the seven patients in California never received a vaccine against the disease, leading some people to question whether vaccines may have prevented possible spread of the virus.  

Utah health officials have released a list of locations visited by the patients, in an effort to alert people who may have been exposed to the virus. Those who have not been immunized against the disease are being asked to isolate themselves for 21 days from the date of possible exposure, in order to avoid spreading the illness.  

"Individuals who came into contact with the two Utah cases may also have been exposed to the virus and public health officials are working to track down and notify these people. The infected individuals in Utah County would have been contagious from December 27, 2014 through January 5, 2015 and attended several events during the infectious period," Utah County Heath Department officials report.

Measles infections are spread through respiratory droplets, released during sneezing or coughing. This highly-contagious disease will infect 90 percent of people who come in contact with a patient, unless they are immunized. The disease causes a distinctive rash that spreads over the body around two weeks after infection, accompanied by fever, cough, and a runny nose.

Immunization against measles consists of a pair of MMR (measles, mumps, and rubella) vaccines.

Health officials believe a person with measles was likely at the entertainment resorts in the middle of December, spreading the disease to guests.

"We are monitoring the situation... nothing is more important to us than the wellbeing of our guests," a Disneyland Resort spokesperson said.

California saw a total of 61 cases of measles in 2014, according to health officials in the state.

"If you have symptoms, and believe you may have been exposed, please contact your health care provider. The best way to prevent measles and its spread is to get vaccinated," Ron Chapman of the California Department of Public Health (CDPH) said.

Measles have been largely wiped out in the United States, and two doses of the vaccine are 99 percent effective at preventing the illness.