Health officials have issued a warning about possible measles exposure at Chicago’s O’Hare Airport. An infected individual spent time in Terminal 1 on April 22-23 between 10am and 8pm, potentially exposing hundreds to the highly contagious disease.

The patient, who had received one dose of the MMR vaccine, developed a rash on April 25 and later tested positive for measles. They are currently isolating at home while health authorities investigate the case.

A second measles case emerged days later in the same Illinois county. The vaccination status of this individual remains unclear. They sought treatment at a local hospital on April 28, where staff immediately placed them in isolation.

Authorities are urging anyone who may have been exposed to monitor for symptoms and contact healthcare providers. Measles symptoms typically appear 7-14 days after exposure and include high fever, cough, runny nose, and watery eyes followed by a rash.

This marks the latest in a series of measles incidents affecting major U.S. airports. The highly contagious virus can linger in the air for up to two hours after an infected person leaves the area, raising concerns about potential spread.

Health officials emphasize that two doses of the MMR vaccine provide 97% protection against measles. They recommend checking vaccination records, especially for travelers and those who frequent crowded public spaces.

The Chicago Department of Public Health is working to identify and notify potential contacts. The incident highlights growing concerns about measles resurgence in the U.S., with multiple outbreaks reported across the country this year.