There have been 151 cases of the disease, including nine deaths, reported in the provincial capital since July, according to Quebec City's regional public health board.
"In respect for the people who died and their families, the coroner has to shed light on these events," Dutil said in a news release.
Quebec's chief coroner confirmed Thursday morning that there will be an inquest into the outbreak of legionellosis, as the ailment is also known.
The source of the outbreak is believed to be the cooling systems atop two buildings in Old Quebec. Local authorities have disinfected the cooling systems in more than 100 buildings.
Inspectors are currently revisiting about 30 of them for reinspections and to make sure building owners have complied with cleanup directives.
Deadly legionella bacteria can grow in the stagnant water of systems called cooling towers, and then spread in droplets through ventilation.
Heavy smokers and people with weak immune systems are most at risk of catching the disease, which is not contagious. Symptoms include persistent fever, coughing and difficulty breathing. Most people are not at risk.
The disease can be treated with antibiotics if it is diagnosed in time. There has never been a documented case of drug-resistant legionella.
'People need to know'
"The scope of this outbreak is stunning," said Jean-Pierre Ménard, a lawyer for one of the victim's widows, Solange Allen.
Ménard and Allen held a news conference Thursday in which they planned to call for a public inquiry into the outbreak — but mere minutes before, the government announced the coroner's inquest.
"We have to question first of all how this started, and once it started, to look at how it was managed. Because public health has important responsibilities here," Ménard said. "People need to know what happened and why it happened."
Ménard has previously launched class-action lawsuits against the Quebec government on public health matters, but he said it's too early to start one over the outbreak of legionnaires' disease.
"We're not currently preparing a lawsuit. We're looking for information," he said. "It's important that the coroner have a chance to do his work."
Allen, whose husband was the fourth person to die during the outbreak, said she's frustrated that doctors never mentioned anything about legionellosis when he checked into hospital with a fever and trembling, and that public health officials never informed her or her husband of the outbreak and that it might have spread to him.
"We never heard talk of it," Allen said. "Public health never contacted me. I want to know who's at fault, and why?"
Both Ménard and Allen said they want the coroner's inquest to look into why recommendations from a 1997 report, published in the wake of Quebec City's previous outbreak of legionnaires' disease, were never implemented.
The report recommended the province create a registry of buildings that use cooling towers in their ventilation systems, so that an outbreak could be more quickly isolated. It also recommended tougher regulations for inspecting and maintaining cooling towers, which are typically installed on rooftops as one of several ways to keep a building's air fresh and control its temperature.
New infections in Quebec City are now highly unlikely, according to the region's public health agency, because every cooling tower in the downtown area has been treated to kill any bacteria. It is possible new cases will still emerge over the next days, however, because the disease has an incubation period.
The worst legionnaires' outbreak in Canada over the last 20 years was in 2005, when 21 people died and 127 fell ill at a nursing home in Toronto.