Thousands of travelers passing through the Midwest’s busiest airport may have been exposed to measles, health officials warn.
Officials said a person infected with the virus, the world’s most infectious, had traveled through Terminal 5 at Chicago O’Hare International Airport.
The individual was in the airport last Tuesday, on March 24, between 10.45 am and 2.30 pm. Last Thursday, March 26, they are also reported to have visited a Fresh Farms store and Marshalls between 7.30 and 9.30 pm.
Officials warn that the patient was contagious at these times, meaning they could have spread the disease to others.
Measles can remain in the air for up to two hours after an infectious person passes through an area. Patients only need to be exposed to the virus for 15 minutes to trigger an infection.
No further details were provided about the patient, including their name, age, where they had traveled from, their symptoms and their current status.
Health officials are warning everyone, particularly unvaccinated individuals, who may have been exposed to the virus to watch for symptoms, which typically start as a cough or fever.
They are also urging everyone to ensure they are up to date on the measles vaccine. Two doses of the shot slash the risk of infection by 97 percent. For unvaccinated people, nine in 10 of those exposed to the virus will get infected.
Officials said a person infected with the virus, the world’s most infectious, had traveled through Terminal 5 at Chicago O’Hare International Airport
Doctors warn that children are particularly at risk from measles. One in every 20 unvaccinated children infected with the disease develops pneumonia, while nearly one in five is hospitalized and up to three in 1,000 die from the disease.
In the alert, officials added that the patient also visited the Endeavor Health Immediate Care Center in Mount Prospect last Friday, March 27.
The address of the Fresh Farms store they visited was 8203 W. Golf Rd. Niles, IL, and the address of the Marshalls was 8249 W. Golf Rd. Niles, IL.
Cook County Health Department, which revealed the infection, said it was now working to identify and contact all individuals who may have been exposed to the virus.
Nationwide, this year is already the second-worst year for measles cases in 34 years.
So far, the US has recorded 1,575 cases of the disease, with 21 infections recorded in the week to March 22 — the latest date that nationwide data is available.
This is already more than double the 652 measles infections that were recorded by this time last year. In 2025, the US registered 2,285 measles cases, making the year its worst for measles since 2000.
Currently, 78 measles patients have been hospitalized, but no deaths have been recorded. There were three deaths last year.
The above notice was released by Cook County Department of Health to warn over the measles exposure at the airport
Ninety-two percent of infections are among people who were not vaccinated against the virus. More than half of the patients are under 18 years old.
The epicenter of this year’s measles outbreak is in upstate South Carolina, where, according to state data, just under 1,000 infections have been recorded.
Last week marked the first time in months that the state had not recorded a new case of the virus, with only two people reported to now be in quarantine. Officials say the area’s outbreak will be declared over on April 26 if no new cases have been reported by that date.
There is also a major outbreak in Utah, which has reported 486 cases since June 2025, and registered 43 new infections within the past week.
In Texas, since the start of the year, 147 measles infections have been detected at detention facilities in Hudspeth and El Paso counties.
In Florida, 128 measles cases have been detected since the start of the year, including more than 40 at a Catholic University in the southwest of the state, marking the largest measles outbreak on a college campus in recent history.
Overall, 31 states have reported at least one measles case so far this year, according to the CDC
Measles spreads through direct contact with infectious droplets or through the air.
Patients initially suffer from a flu-like illness before the characteristic rash emerges three to five days later. It normally starts as flat red spots that appear on the face and hairline before spreading down the neck, trunk and arms to the legs and feet.
Early flu-like symptoms that emerge within seven to 14 days of infection include a high fever, cough, runny nose and red, watery eyes.
The infection starts in the lungs but, in serious cases, it can also spread throughout the body and affect the brain and central nervous system.
Among unvaccinated people, nearly one in 1,000 children who are infected with measles develop encephalitis, or swelling of the brain.
This can lead to convulsions and leave a child deaf or with intellectual disability.
Measles also severely damages a child’s immune system, making them susceptible to other potentially devastating bacterial and viral infections they were previously protected against.
Before MMR vaccines became available in the 1960s, measles caused epidemics with up to 2.6 million global deaths every year. By 2023, that number had fallen to roughly 107,000 deaths.
