The Cook County Department of Public Health on Tuesday confirmed the second case of measles in the Cook County suburbs of Chicago this year.

The department said the patient was a 4-year-old child who was not vaccinated. The suburb where the child lived was not identified.

The department believes the child got measles during international travel, and is working with the Illinois Department of Public Health to identify anyone who may have been exposed.

Terminal 5 at O'Hare International Airport between 7:30 a.m. and 11 a.m. Thursday, Sept. 11, has been identified as a point of public exposure.

Anyone who may have been exposed should check with their health care provider if they're not sure whether they have been vaccinated. A doctor will determine the need for testing if symptoms come up.

Measles was believed to have been eliminated in the United States in 2000. But cases have steadily increased in recent years, with a massive outbreak around the country this year.

A total of 10 measles cases were confirmed in Illinois before this latest one — including one in Chicago and another in suburban Cook County.

Chicago also saw its own measles outbreak just last year — affecting in particular the migrant shelter in operation at the time in Pilsen. There were 67 cases reported in the March and April 2024 Chicago area outbreak altogether.