They say samples taken from a cooling tower in a building on St-Joseph Street in Quebec City's lower-town area match the shape of legionella bacteria found in patients who've been treated.
Public health officials told a news conference today that the tower is safe again and there's no reason for people to modify work or leisure activities.
They say their conclusion is based on preliminary information released by the laboratory conducting the tests.
From the start, the source of the outbreak was suspected to have been an office cooling tower. Authorities scrambled to ensure all the towers were cleaned in the affected areas, while at the same time seeking to pinpoint the actual origin.
Since the outbreak began in July, 180 cases have been reported. Thirteen people have died.
The deadly bacteria grows in the stagnant water of cooling systems and spreads in little droplets through air conditioning.
While authorities haven't ruled out other buildings, they say the tower on St-Joseph Street played an important role in the outbreak in that city.
Authorities say the illness has been brought under control because they have disinfected the cooling systems in more than 100 buildings in the area.
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