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Legionnaires Disease and Pontiac Fever

Legionella pneumophila bacteria

Legionnaires' disease and Pontiac fever are both forms of a disease called legionellosis,   an uncommon respiratory infection caused by Legionella pneumophila bacteria. If you have a hot tub, the most important thing to know is how to maintain the water quality and disinfectant levels to prevent infection.

Information for Health Professionals

Legionella are bacteria that infect the lungs. When a person gets sick from this infection it is called legionellosis. The serious form of legionellosis is called legionnaires’ disease. A milder form of the infection is called Pontiac fever. 

Legionella infections are rare in British Columbia. From 1999 through 2008, 34 cases have been reported to the B.C. Centre for Disease Control. 


The most significant cause of legionellosis is the bacterium Legionella pneumophila. Legionella infections are NOT spread from person to person. The bacteria are naturally found in the environment, most often in water. People become infected when they breathe in spray or mist coming from contaminated water. 

There have been individual cases and outbreaks linked to:

  • air conditioning systems in large buildings
  • hot tubs
  • decorative fountains 

Legionnaires’ disease produces symptoms similar to pneumonia, including:

  • loss of appetite 
  • muscle pain 
  • headache, followed by: 
  • high fever
  • chills
  • cough 
  • abdominal pain, and 
  • diarrhea

Symptoms start an average of 5 to 6 days (range 1 to 19 days) after exposure to the bacteria. 

Pontiac fever causes mild symptoms of:

  • fever
  • headache, and
  •  muscle aches that go away without serious problems.

Symptoms start an average of 24 to 48 hours (range 5 to 66 hours) after exposure to the bacteria. Sometimes a person can be infected and have no symptoms. People at most risk of infection and serious illness from a legionella infection are those over the age of 65, smokers, those who have a lung disease such as emphysema and those whose immune system is compromised.


If you think you have a legionella infection, see your family doctor immediately for testing, advice and treatment. Contact your local environmental health officer to discuss where the infection might have come from, especially if you suspect a public facility as the source.


Your doctor will decide which treatment is right for you. Antibiotics are effective in treating most people with this infection.  


If you own a hot tub, disinfection of the water can prevent the growth of legionella that might naturally be present in the water.

  • Make sure there is enough disinfectant in the water prior to using your hot tub.
  • If necessary, add disinfectant at least a half an hour before using the hot tub. 
  • Chlorine levels should be maintained at 3.0 ppm and bromine levels should be maintained at 4.5 ppm. Test kits are available at hot tub and swimming pool stores.

For information about hot tub use and maintenance refer to HealthLink BC Hot Tubs: Health and Safety Tips #27a and Hot Tubs: Maintaining Safe Water Quality #27b

Proper construction and maintenance of air conditioning systems in large buildings and decorative fountains is required to ensure that legionella bacteria do not multiply.   

SOURCE: Legionnaires Disease and Pontiac Fever ( )
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