Infographic: What is Legionella

Infographic: What is Legionella

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Organization: Health Canada

Date published: 2021-05-28

Cat.: H144-86/2021E-PDF

ISBN: 978-0-660-38712-3

Pub.: 210069

Legionella is a group of bacteria found in natural water sources, such as lakes, streams and groundwater. It can also be found in human-made water systems and devices.

Legionella can become a health concern when it grows in these systems and devices, and is inhaled in the form of droplets and mists released into the air.

Possible sources of Legionella

  • hotubs
  • humidifiers
  • water heaters
  • decorative fountains
  • showerheads and sink taps
  • home plumbing systems
  • building plumbing systems
  • cooling towers (cooling towers for buildings)

Conditions that support Legionella growth

  • warm temperatures
  • standing or still water
  • settled particles and biofilm (a slimy, glue-like material containing microorganisms and nutrients)

Health effects of Legionella

Legionella can cause two types of illness in humans: Legionnaires' disease and Pontiac fever.

Legionnaires' disease is a serious respiratory illness that results in pneumonia, lasting weeks to months, and can lead to death.

Pontiac fever is a milder illness, causing flu-like symptoms. People with Pontiac fever generally recover in 2 to 5 days without treatment.

Who is at greatest risk

  • people over 40 years of age
  • current and former smokers
  • people with chronic lung disease
  • people with underlying illnesses and weakened immune systems

How to reduce your risk

  • Maintain your water heater temperature at 60°C
    • To reduce the risk of scalding the temperature of the water at the tap should be no higher than 49°C. You should contact a qualified plumber to install mixing valves to control the tap water temperature.
  • Regularly clean and disinfect mist-producing devices in your home (shower heads, humidifiers, hot tubs) according to manufacturer directions
  • Run the hot and cold water taps for a few minutes after not using them for more than two weeks
  • Periodically drain and flush your water heater, according to manufacturer directions, to reduce settled particles

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