Legionella

What is Legionella?

Legionella are a type of bacteria that are found in natural water sources which can also grow in human made water systems. These bacteria can cause two different types of illnesses in humans: Legionnaire’s disease and Pontiac fever. 

What is Legionnaire’s Disease?

Legionnaire’s disease is a serious illness and can result in pneumonia.

What is Pontiac Fever?

Pontiac fever is a milder illness with flu-like symptoms. 

What are symptoms of Legionnaire’s Disease?

  • Fever
  • Cough 
  • Muscle pain 
  • Headache 
  • Can cause pneumonia 

It usually takes 2 to 14 days after contact with the bacteria for you to feel symptoms. It often takes several weeks or in some cases months to recover. 

What are symptoms of Pontiac Fever?

  • Fever
  • Chills 
  • Headache 
  • Muscle pain 
  • Malaise

It usually takes about 48 hours after encountering the bacteria for you to feel symptoms. These symptoms usually last 2-5 days and do not require treatment. 

How does Legionella spread?

  • Legionella can not be spread from person to person.
  • Legionella can be found in natural sources of water including lakes, ponds, rivers, and streams.
  • The number of bacteria in the water source determines the level of risk for humans. 
  • When a water source has many legionella bacteria, the bacteria are released into the air and form droplets or mist. Exposure occurs when people breathe in this contaminated air. 
  • Legionella can occur in multiple different settings such as homes, commercial buildings, spas, cruise ships or healthcare facilities. 
  • Stagnant water, water temperatures between 20℃ and 50℃, the presence of biofilms, scale or sediment are conditions that promote the growth of these bacteria.
  • The conditions as mentioned above can be found in air conditioning systems, whirlpools, hot tubs, public spas, plumbing systems and humidifiers.

Who is at risk?

  • People over the age of 40 
  • Smokers 
  • Alcoholics 
  • Individuals with chronic lung or kidney disease 
  • Individuals living with diabetes 
  • Anyone with a weakened immune system 
  • People in occupations such as maintenance workers of large air conditioning systems 

How is Legionnaire’s disease treated?

Legionnaire’s disease must be treated with antibiotics. 

Pontiac fever often does not require any treatment. 

How is Legionnaire’s disease prevented?

Ways to prevent infection include:

  • Proper cleaning and disinfecting of mist producing devices such as shower heads, whirlpools, hot tubs, and humidifiers. These should be maintained regularly. 
  • Keep your home water heater at a suitable temperature - a minimum of 60℃ is best. To reduce the risk of scalding yourself or others the water temperature at the tap should be no higher than 49℃ .
  • A qualified plumber should be hired to install mixing valves to control the water temperature of the tap. 

For more information, contact the Health Unit or speak to your health care provider.


References:

Ontario. Public Health Standards: Requirements for Programs, Services and Accountability. (2022). Infectious diseases protocol, Appendix 1:Case Definitions and Disease-Specific Information, Chapter: Legionellosis. Toronto, ON: Queen’s Printer for Ontario.

Public Health Agency of Canada. (2019). Legionella. Retrieved from https://www.canada.ca/en/public-health/services/infectious-diseases/legionella.html

World Health Organization. (2022). Legionellosis. Retrieved from https://www.who.int/news-room/fact-sheets/detail/legionellosis