Six states in America and some places in Mexico are experiencing an outbreak of measles that began in Disneyland before Christmas.

USA Today reports hundreds of people have been exposed to measles at several locations, while nearly 70 have been diagnosed in Arizona, Utah, Washington, Colorado, Oregon, California and across the border to Mexico. A woman in her 50s was diagnosed with one of the most contagious diseases recently, making Arizona the latest state to experience the outbreak.

Schools and hospitals have been proven to be the most common place to contract measles.

Nearly 250 people may have been exposed to measles at Penrose Hospital in Colorado Springs after a patient came in for treatment.

An infected child exposed nearly 30 children to the virus at a California doctor's office in Oakland. Unvaccinated children were urged to stay home in several California school districts since a few infected students came to school.

More than 80 percent of the patients infected in the measles outbreak have not been vaccinated, according to USA Today. Nineteen states, including California, where the most people are infected with measles, allow students to skip vaccinations for philosophical reasons.

Parents who object to vaccines are more likely to cluster together in like-minded communities, which make it easier for viruses like measles to spread.

Deputy Director of the California Department of Public Health said about 24 students at Huntington Beach High School have not been vaccinated.

About five employees at Disneyland developed measles after an infected person came to the amusement park or the park right next to it in December.

Disney has offered vaccinations and immunity tests to employees "out of an abundance of caution," Pamela Hymel, chief medical officer at Walt Disney Parks and Resorts, said. Employees who have been in contact with infected co-workers are being tested for measles and will be on paid leave until they are cleared.

It is unclear of who exactly started the outbreak.