There was an outbreak in 2014 that began with an infected child at Disneyland that led to 140 confirmed cases but no deaths

A woman in Washington died from measles last spring, the first death from the disease in the US for 12 years

who was already vaccinated that first caught the disease from the infected inmate

An outbreak of measles that began with an inmate at a federal detention center for immigrants in central Arizona has now grown to 11 confirmed cases.

Seven of those infected are inmates at the Eloy Detention Center, and four are workers at the facility, Pinal County Health Services spokesman Joe Pyritz said.

The privately-run facility has stopped accepting new detainees or releasing those currently held there.

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.

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A measles outbreak in Arizona has been traced back to an immigrant inmate at Eloy Detention Center (above)

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 it anyway.

Health officials put out the first warning of the initial two cases last Thursday.

They 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 locations can be found here.

The Arizona Department of Health Services is working with county officials to try to identify people exposed outside the facility.

They're also urging people who may have visited any of the identified locations to come forward and be alert to measles symptoms, which include fever, red, watery eyes, cough and runny nose and is followed by a rash that is red, raised, and blotchy.

The rash begins on the face at the hairline and moves down the body and may last five to six days.

'People who have a rash and fever must call their health care provider or emergency department before going to let them know they may have measles,' Dr. Cara Christ, director of the state health department, said in a statement.

'It is vital to help stop the further spread of the disease.'

Measles is a highly contagious, vaccine-preventable viral illness and symptoms can appear up to 21 days after exposure.

Vaccination prevents about 95 per cent of cases, Pyritz said, and the low numbers currently seen in a facility that can house more than 1,500 detainees shows that it is effective. The first worker who was sickened was vaccinated, Pyritz said.

'There are a lot of people who have been exposed, and then we've had a few breakdowns' in immunity, Pyritz said.

'Not many, but a few.'

A woman in Washington died from measles last spring in the first measles death in the U.S. since 2003.

The Washington outbreak followed an outbreak of measles at Disneyland in California late in 2014, which sparked an intense debate across the nation about mandating vaccinations for schoolchildren, which some parents oppose.