The Illinois Department of Public Health (IDPH) is investigating two cases of Legionnaires’ disease in patients possibly exposed at Mercy Hospital & Medical Center in Chicago, and a report of Legionella in the facility’s water system.  The investigation is currently limited to this facility; the general public is not at risk.

IDPH, along with the Chicago Department of Public Health (CDPH), were onsite Thursday to evaluate the reported presence of Legionella in the hospital’s water system and collect environmental samples for laboratory testing. Both agencies continue to collect information and investigate. IDPH has provided the facility with information to give to patients and families about Legionella. Additionally, the facility is conducting active surveillance to identify other potential cases and to ensure appropriate testing and clinical management.

Mercy Hospital & Medical Center is working with a water management team, IDPH and CDPH to strengthen its water management practices. The facility has already put protective measures in place like flushing the water system, altering or replacing water fixtures, and placing filters on sinks.

Legionella bacteria
Image/CDC

Legionnaires’ disease is a respiratory infection caused by Legionella bacteria. These bacteria can also cause a milder illness called Pontiac fever. The signs and symptoms of Legionnaires’ disease include fever, cough, shortness of breath, muscle aches, pneumonia, and sometimes diarrhea and abdominal pain. Pontiac fever has similar symptoms but does not progress to pneumonia. Antibiotics are highly effective against Legionella bacteria.

Legionella bacteria are commonly found in the environment (rivers, lakes, streams). It is a waterborne disease, usually spread by man-made water supplies that aerosolize water, such as showers, hot water tanks, cooling towers, whirlpool spas, and decorative fountains. People can get Legionnaires’ disease when they breathe in a mist containing the bacteria. People may also be exposed to Legionella bacteria from water that “goes down the wrong pipe” (aspiration). In general, the bacteria are not spread from one person to another.

People who are at most risk of developing Legionnaires’ disease are those who are older, smokers/former smokers, have a weakened immune system, and those who have other underlying or chronic health conditions.