Precautions are now in place to prevent any further cases.
Evanston's YWCA on Church Street is closed Friday, after the city's Health and Human Services Department identified two positive cases of Legionnaires' disease.
The health department said the two individuals reported exposure at the YWCA.
A white piece of paper is posted on the front door of the facility.
It says all aquatics programming is canceled, as of Thursday.
According to the Evanston health officials, Legionnaires' disease spreads through building water systems, like showers, sink faucets, hot tubs and hot water tanks.
Officials say legionella was detected in some YWCA water systems, and confirmed through lab tests.
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Evanston health officials released a statement on the findings, writing in part, "Legionnaires' disease is not contagious and cannot be transmitted from person to person. If you have recently visited the YWCA at 1215 Church Avenue and think you have been exposed or are experiencing any symptoms, consult your medical provider for further instructions."
Dr. Jonathan Pinsky is an infectious disease specialist from Endeavor Edward Hospital in Naperville.
Pinsky said people who are immunocompromised are most at risk for developing severe cases.
"The symptoms of legionella pneumonia: It can start with fevers, myalgias, gastrointestinal symptoms. When it becomes a pneumonia, people often have respiratory symptoms, which could include cough, shortness of breath, trouble breathing, chest pain," Pinsky said.
Evanston health officials also say they are working with the Illinois Department of Health and YWCA leadership to rectify the situation.
The water was shut off to the facility Thursday.
It is unclear when the YWCA will reopen.
The YWCA did not immediately respond to a request for comment on the situation.