An international traveler with a confirmed case of measles went through O’Hare Airport last week, according to the Chicago Department of Public Health.
The traveler may have exposed others to the virus in Terminal 5 on June 17 between 5:50 a.m. to 9:30 a.m., the agency said in a news release.
The virus can remain in the air for up to two hours after an infectious person has left the area, though transmission requires just 15 minutes of exposure.
People experiencing symptoms — rash, high fever, cough, runny nose, and red, watery eyes — should call a health care provider before going to a clinic to help control the spread of the virus, the agency said. Measles symptoms appear up to 21 days after exposure, as well as four days before and four days after the onset of the rash, which starts on the face and spreads to the body.
Those most at risk are babies, young children, pregnant women and people with compromised immune systems. Vaccinated people are typically not at risk. The health agency advises those who may have been exposed to consult a health care provider.
Those not vaccinated should talk to their provider about getting vaccinated, as doing so can prevent measles if administered within 72 hours after exposure, the health agency said.
An appointment with a Chicago city clinic for a vaccination can be made online, though walk-ins at its four clinics are also welcomed.
It’s the second time O’Hare’s Terminal 5 has had a potential measles exposure this year.
Illinois saw 14 measles cases last year during the peak of an outbreak, during which nearly 1,300 cases cropped up nationwide. It was the worst surge in more than 30 years. But that outbreak was a significant drop from Chicago’s three-month measles surge in 2024, when 64 cases were confirmed.