Health officials in Illinois are trying to find the source of a measles infection, after five babies were diagnosed with the contagious respiratory disease in a Chicago suburb. Saying that more cases are likely, a health official warns, "The cat is out of the bag."

Because the Illinois patients are all under a year old, they can't be vaccinated. The new cluster of cases joins more than 100 other reports of measles in 14 states this year; most of them have been traced to an outbreak at Disneyland in California in December.

From Chicago member station WBEZ, Patrick Smith reports:

"The infants all attend KinderCare Learning Center in Palatine, Ill. So far, two have tested positive for the disease and another three have been diagnosed based on their symptoms."Dr. Kiran Joshi with the Cook County Department of Public Health says more children were exposed. He says public health nurses are reaching out to about 10 families to provide guidance. Unimmunized children won't be allowed in the day care center for the next few weeks."

The new cases come a week after the Chicago area's first measles diagnosis; local TV news ABC 7 says officials don't think the cases are related.

"We will do everything we can to identify if there is a point source, we're try[ing] to do our best identifying that. But at some point the cat is out of the bag," says Dr. Terry Mason of the Cook County Department of Public Health, according to the station.

KinderCare, a national chain that operates some 1,600 child care centers, says it's "working diligently" with Cook County on the case.

The recent spate of measles cases has put new focus on vaccination laws like that of California, one of 19 states where parents don't have to vaccinate their children before enrolling them in school, as NPR's Shots blog reported Thursday.

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