Six babies under the age of 1 and one adult have been diagnosed with measles in a cluster linked to a day care center in suburban Chicago.
The Cook County Department of Public Health had previously reported that five babies linked to the facility had been diagnosed, but said Monday more cases had been confirmed.
An adult linked to the center was also diagnosed with the disease, the department said. All of the people who were diagnosed were unvaccinated.
At least four of the babies live in Cook County, Illinois, and at least one lives in Chicago. They all have been linked to a KinderCare Learning Center in Palatine, Illinois.
Officials said they aren't yet sure what the source of the outbreak was, nor do they know if it is linked to the outbreak stemming from Disneyland.
All unvaccinated people at the day care facility have been ordered to stay home, officials said.
Last month, state officials confirmed that a resident had been diagnosed with measles in Springfield, Illinois.
Officials said they are not sure if the day care outbreak is linked to the previous case.
The cases announced on Monday bring the total of cases in the county to eight.
Cases of the once nearly eradicated virus have been cropping up across the U.S. since December of last year.
The outbreak was sparked by exposure at Disneyland in Anaheim, California. Cases of the virus have steadily been on the rise as vaccine rates decline.