QUEBEC - Legionnaires' disease has claimed another life in Quebec City, bringing the total to 11 since the outbreak began in mid-July.

Public health officials have now confirmed 169 cases in all — four more than on Saturday.

But officials say the outbreak is under control.

They say the most recent cases developed over the past 10 to 15 days and are only now surfacing because of a delayed incubation period.

The source is thought to be the cooling systems of two building towers, where the deadly bacteria grow in stagnant water.

Local authorities have cleaned out the systems in over 100 buildings in the Quebec City area.

The Quebec government called a public inquiry into the outbreak last week.

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  • The Name

    Legionnaires' disease" got its name from the unfortunate delegates who became infected during an outbreak at an American Legion of Pennsylvania convention. Thirty-four people died.

  • It's A Type Of Pneumonia

    Legionnaires' disease, a severe pneumonia, is one of two distinct illnesses associated with the Legionella genus.

  • Linked To Wet Environments

    Legionella bacteria are found in water sources, and can survive for several months in an aquatic environment - especially in warm water or when algae and organic matter are present. The bacteria may also do well in household devices, particularly those that produce mist -- shower heads and humidifiers, for instance.

  • Cannot Spread From Person To Person

    People may become ill if they inhale steam or mist containing the bacteria that causes legionnaires' disease, but they cannot pass an infection on to others. More recent research suggests that Legionella microbes may enter the lungs if someone chokes while eating or drinking, thereby allowing fluids and particles to enter the lungs instead of the stomach.

  • Starts With A Headache

    The Canadian Centre for Occupational Health and Safety notes that the first sign of legionnaires' disease is usually a headache accompanied by pain in the muscles and "a general feeling of unwellness." These symptoms may be followed by high fevers, shaking chills, coughs, fatigue, loss of appetite, nausea, diarrhea, hallucinations and more.

  • Older, Less Healthy People At Risk

    Not everyone who is exposed to the bacteria develops legionnaires' disease. People under age 20, for instance, are much less vulnerable. Middle-aged and older people are at greater risk, as are smokers. People who have diabetes, a weakened immune system and/or a chronic lung or kidney disease are also at increased risk when exposed to the bacteria.

  • Usually Not Fatal

    The majority of those infected survive, although their recovery can take several weeks. About five to 15 per cent of known cases have been fatal. The odds of recovery depends on many variables, such as age and overall health, as well as the timeliness of medical treatment.