CHICAGO (AP) — Two more children in suburban Cook County have come down with measles, bringing the Illinois tally of confirmed cases to 13.

The Illinois and Cook County public health departments updated their measles counts late Friday. Twelve of the 13 cases are associated with a KinderCare Learning Center in Palatine.

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Health officials are still investigating possible causes for the cluster of cases. The disease is highly contagious. Ninety percent of people who aren’t immunized are infected if exposed to the virus.

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In Kane County, the health department is offering measles vaccines to unvaccinated students and employees at Elgin Community College who may have had contact with one of the reported cases. The college’s website says the health department has sent emails to the students and employees who may have been exposed.

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