Travelers passing through Chicago's Midway International Airport last week may have been exposed to measles.
The Illinois Department of Public Health says an unvaccinated Illinois resident passed through Midway on Feb. 22. Department officials announced Thursday people in the airport between 9 p.m. and midnight may have been exposed.
The infected person sought treatment at Northwestern Medicine Delnor Hospital in Geneva. Those in the emergency department Feb. 24 and Feb 25 also may have been exposed.
Public health officials say measles is spread through the air when someone coughs or sneezes and can also spread through contact with mucus or saliva from an infected person.
Those infected by measles may not develop symptoms for weeks. Symptoms include a rash, high fever, cough, runny nose, and red and watery eyes.
The measles vaccine is about 97 percent effective in preventing the disease.