Health officials say a passenger arriving on an global flight last Wednesday had a contagious case of measles.
The traveler landed from an worldwide flight at terminal five and departed at terminal one.
People are at risk if they were at the airport between 6:30 a.m. and 1 p.m. on January 10.More news: Jacksonville Jaguars to play Philadelphia Eagles in 2018 game in London
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Somewhere between the hours of 6:30 a.m. and 1 p.m. on January 10, according to a statement obtained by ABC News and released by the Illinois Department of Public Health, "a passenger on an worldwide flight with a confirmed case of measles arrived in Terminal 5" of the airport and the person "departed on a domestic flight from Terminal 1".
Last week, a female college student traveling from Mumbai, India, traveling to Indianapolis International Airport by way of Newark Liberty International Airport, was confirmed to have been diagnosed with measles.
For early detection, the Centers for Disease Control and Prevention suggests looking for Koplik spots. The disease is highly contagious and can take up to ten days for symptoms to appear.
Travelers who were not at O'Hare that day are not at risk, but some say they are still anxious. If you have been exposed, you are at risk if you have not been vaccinated or have not had measles. If symptoms of measles develops, IDPH recommends people should call a health care provider before going to a medical office or emergency department. People can also get sick when they come in contact with mucus or saliva from an infected person. Symptoms include a rash that starts on the face and neck, a high fever, runny nose, cough and red, watery eyes. The disease is most easily spread through coughing and sneezing and can cause further complications such as pneumonia or encephalitis.