The trickiest thing about legionella, the deadly bacterium that has killed nine people in Quebec City and sickened 158, is that it could be anywhere.
It's entirely possible there's a species in your nasal passages right now. Chances are you'll be fine.
But for the very old, the very young, smokers or people with battered immune systems, inhaled bacteria can cause severe pneumonia that can kill up to a third of those it infects.
And it's hard enough to spot that, once you know what it is, it could be too late.
Nearly four decades after sick legionnaires at a Philadelphia hotel gave the disease its name, public health organizations are better at diagnosing it. And while the rate of infections among Canadians has more than doubled in the past eight years, health officials say that's due in large part to better detection.
But the preventive measure proposed 15 years ago on which every Quebec political party has promised to follow through is not yet common practice. And some outside the province say the cost of that promise – to register and inspect air conditioning cooling towers, a common source of the bacteria – could sap limited public health resources.
The sheer number of people infected makes the late-summer outbreak one of the biggest in Quebec's history. It sent public health officials scrambling to identify and neutralize the source of the disease, manage a growing list of sick people and reassure a spooked public.
The province's Health Minister blamed a previous, Parti Québécois government. Quebec City's mayor blamed the current Liberal government. The Premier promised a probe, followed by the Public Security Minister's pledge of a public inquiry that may or may not be followed by class-action suits.
On Friday, public health officials announced another seven cases, bringing the number of people infected in Quebec City in the past two months on par with the total infected across Canada throughout 2011.
Think of Contagion, the blockbuster film about an epidemic, without the contagion: Legionnaires' disease isn't transmissible from person to person, just inhaled into the lungs as imperceptible water vapour.
Instead of desperately trying to quarantine infected people before they can sicken others, public health officials and epidemiologists pump them for information in the hopes their memories and detailed analysis of their bodily fluids will trace the source of the disease so they can disinfect it and prevent future contamination.
"It's kind of like detective work," said Bonnie Henry, medical director of communicable disease prevention at the B.C. Centre for Disease Control. "You piece together puzzles on where people might have been connected."
Legionella is a tiny tubular creature that grows as sludgy biofilm in warm water. The species most likely to sicken people is legionella pneumophila (serotype one, to be specific). It lurks in microscopic droplets that can vaporize into the air from cooling towers, fountains, steamy hot tubs, hospital taps, produce misters in grocery stores or aquarium facilities.
The late summer's a common time for spikes in legionnaires' cases. On Friday, Chicago health officials confirmed a third death tied to an outbreak at a city hotel.
Fifteen years ago, a report on Quebec's response to a previous legionnaires' outbreak recommended a system of registering and inspecting the province's cooling towers – the source of that outbreak and the parts of buildings' air-conditioning systems that can become perfect legionella breeding grounds if not cleaned properly.
That system was never put in place, an omission all provincial parties have promised to remedy. But that kind of database would be expensive to set up and monitor. "The question then becomes, 'Where are you going to get those resources from?'" said Howard Shapiro, Toronto's associate medical officer of health. "Are we going to give up existing work?"
One of the hardest parts of public health is effective communication with the public.
That's one area where Quebec City health officials have been criticized. Solange Allen said she had heard nothing about the legionnaires' outbreak when her husband, Claude Desjardins, fell ill almost a month after the first confirmed death. Mr. Desjardins had blood samples taken when his condition worsened, then went home before being rushed back to hospital. He died less than a week after getting sick.
"I never heard anyone talk about legionnaires' disease," she told reporters. "Never, ever."
Otto Rada knows the feeling. He was barred from his mother's Toronto nursing home in 2005 when residents, staff and visitors fell ill by the dozens to a sickness doctors couldn't identify for days.
His 89-year-old mother, Anna Rada, was one of the last to get sick. She died in a Scarborough hospital. Her son took her ashes back to her hometown in Nitra, Slovakia.
The Rada family was part of a class action launched against the city-run Seven Oaks nursing home. Mr. Rada is convinced the deaths, later linked to an air-intake vent beside the building's cooling tower, could have been prevented. He's still incensed patients and their families were in the dark for so long.
"Before she died, she kept repeating, 'Why am I so sick?' She couldn't believe it."