At least 11 people have died in Quebec City due to complications from a legionnaires' disease outbreak, said Quebec's public health board, according to CBC News.
As of Sunday, 169 people had been infected since the outbreak began in July.
Canadian authorities did not pinpoint the source of the outbreak, according to CNN. The Regional Directorate of Health said test results from samples might take until mid-September.
The National Post said the deadly bacteria behind the disease grow in stagnant water in cooling systems, spreading the droplets through air conditioning.
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Those most at risk of being infected with legionnaires' disease include heavy smokers and those with weakened immune systems. It is not contagious, but symptoms include fever, coughing and difficulty breathing, CBC reported. The disease can be treated with antibiotics if caught in time.
The authorities said they have disinfected the cooling systems of more than 100 local buildings. Inspectors plan to return to 30 cooling systems over the next few days to test the water quality, according to The National Post.
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On Friday, Quebec City Mayor Régis Labeaume said he wanted the locations of buildings where legionella bacteria was discovered to be released, CBC reported. The authorities said the number of cases is tapering off.
Chicago has also seen three deaths connected to legionnaires' disease, all connected to visits to the JW Marriott, according to The Huffington Post. Health officials in Chicago have identified the source of the outbreak as the decorative fountain in the hotel's lobby.