Arizona is the latest state to experience an outbreak of measles, and 11 cases have been confirmed so far. The outbreak has been traced to an illegal immigrant who is currently detained in the Eloy Detention Center, an immigration detention center. Seven of the people infected are inmates at the center, and four are workers.

At least one of the workers who caught the measles had been vaccinated previously. The vaccine fails about 10 percent of the time. To stop the spread of the infection further, the facility is no longer accepting new people nor is it releasing people. Additionally, officials are warning people who may have come into contact with an infected person at a public location.

State and county health officials said they're working to stop new transmissions by isolating patients, vaccinating people detained in the privately-run facility and trying to identify people who were at locations the four infected workers visited. The outbreak began when an infected inmate was brought to the facility and spread the disease to a worker, who had been vaccinated but caught the disease anyway. Health officials put out the first warning of the initial two cases last Thursday. Health officials have identified 14 locations in Pinal and Maricopa counties where the infected workers may have exposed other people, including stores, restaurants and a tribal casino.

The last large outbreak of measles in the United States was traced back to Disneyland. A tourist with the illness infected dozens of people; most of whom were either unvaccinated by choice or who were too young to be vaccinated.