Chicago Health Officials Warn of Measles Exposure at Union Station

Anyone who walked through Chicago's Union Station on the evening of August 27 or at any point on August 28 is being told to watch themselves for signs of measles, according to the Chicago Department of Public Health.

The department said a person later confirmed to have measles spent multiple hours inside the station starting after 8 p.m. on Thursday, August 27. Because the person was contagious during that window, anyone in the station at the same time, along with everyone who passed through the following day, August 28, may have been exposed.

The Chicago Department of Public Health set September 18 as the outer boundary for symptom monitoring. Measles symptoms can take anywhere from seven to 21 days to show up after a person is exposed, and the department is asking people to track how they feel through that full three week window rather than assume they are in the clear after a few days.

The guidance differs depending on vaccination and infection history. People who are already immune to measles, either because they had the disease before or received the MMR vaccine, only need to watch for symptoms during the 21 day window. People who are not immune are being told to stay home and quarantine for up to 21 days after the exposure date, a step the department says protects other people who may not be able to get vaccinated, including infants and people with weakened immune systems.

Measles spreads through the air when an infected person coughs or sneezes, and the Chicago Department of Public Health says the virus can linger in an enclosed space for hours after that person has left. Thousands of commuters and Amtrak passengers pass through Union Station daily, and the department says that volume means people who never had direct contact with the infected traveler could still have been exposed.

Early measles symptoms include a high fever, cough, runny nose and red, watery eyes. A rash typically follows, starting on the head and spreading down the body. People infected with measles can spread the virus for about four days before the rash appears and four days after, meaning someone can be contagious without yet showing the telltale skin symptoms.

Measles was declared eliminated in the United States in 2000, meaning the disease no longer spread continuously within the country. Cases since then have mostly stemmed from travelers who picked up the virus abroad and brought it back, sometimes sparking clusters in communities with lower vaccination rates. The Chicago Department of Public Health has not said where the Union Station patient may have contracted the virus.

The department has not released the patient's age or any other identifying details, citing medical privacy. It also has not said whether any additional cases have been linked to the exposure so far.

Residents with questions about their vaccination status or possible symptoms are directed to the Chicago Department of Public Health's website, which has guidance on measles symptoms, transmission and vaccine records. People who develop fever, cough or a rash after passing through the station are advised to call their doctor or an urgent care clinic before showing up in person, so the facility can take precautions to avoid exposing other patients in the waiting room.