Health officials are investigating three confirmed cases of Legionnaires' disease among people who stayed at a Chicago hotel.
The Chicago Department of Public Health and the JW Marriott Chicago Hotel issued an advisory Tuesday. They say guests with symptoms who stayed at the Adams Street hotel should contact their doctors.
Symptoms include headache, high fever, chills, cough, chest pain and shortness of breath.
The city and the hotel are notifying the 8,500 guests who stayed there from July 16 through Aug. 15.
Authorities say they've identified the source of the bacteria and there's no ongoing health risk.
The Centers for Disease Control confirms it could have emanated from water and vapor in either the hotel's air conditioning system or the Valeo pool and spa which uses a unique water treatment system that requires less chlorine than drinking water.
The bacteria that cause Legionnaires' disease grow in water and can spread through vapor in air-conditioning ducts or mist from a whirlpool spa.
An independent contractor hired by the hotel and city inspectors took water samples and swabbed the whirlpool and pool in the hotel's spa, along with the lobby fountain.
Symptoms of Legionnaires' disease include headache, high fever, chills, cough, chest pain and shortness of breath.
The hotel is housed in an historic Daniel Burnham building renovated just two years ago for almost 400 million dollars.