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What illnesses are associated with Legionella? 

Legionella pneumophila is a bacteria that can cause Legionellosis, which takes the form of Pontiac fever or Legionnaires’ disease. Pontiac fever is a milder illness, and usually lasts 2-5 days. Legionnaires’ disease is more a serious illness and may require antibiotics and hospitalization.

Symptoms of Legionnaires’ disease may include:

  • fever
  • chills
  • dry cough
  • muscle aches
  • headache
  • loss of appetite
  • diarrhea
  • pneumonia  

Symptoms of Pontiac fever may include the symptoms above, with the exception of pneumonia. 

More information on Legionnaires’ disease can be found here.

People under 20 rarely get Legionnaires’ disease. Those over age 40, people who smoke or have chronic health conditions, may be more susceptible but overall risk is low. The period between being infected with the bacteria and the first symptoms of the disease (the incubation period) can range from 2-14 days. Public Health does not test people for Legionella unless they are presenting with symptoms. 

What causes Legionella?

The source of most Legionella infections is breathing the mist from a contaminated water source, such as hot water systems (showers) or air conditioning cooling towers. Legionella bacteria can be found in any water source – lakes, pools, hot tubs, hot water systems, air cooling towers among others. Usually there are not enough bacteria to be harmful, and the risk of getting Legionnaires’ disease is extremely low.  

Legionella bacteria can become a problem when they are able to multiply (i.e., in water that is stagnant for a long period of time and where water temperature is between 20C and 50C). It is the responsibility of building operators to exercise due diligence by having routine operation and maintenance protocols, including inspection and cleaning of higher risk water systems, to reduce the risk of Legionella.

Legionella cannot be spread from person to person.

What is the role of Public Health?

Legionella is a notifiable disease to Public Health under the Health Protection Act. Similar to other notifiable diseases, clinical colleagues would treat the case. Public Health’s role is to interview the case(s), review the clinical information, identify the possible source of exposure and put control measures in place when necessary. This is of particular importance when clusters of Legionellosis are identified. Public Health also provides education to the case(s) and others who may be exposed around Legionellosis. 

If the case or cluster of cases are linked to a common source such as public water supply, cooling tower, or recreational water site, Public Health works closely with Nova Scotia Environment & Climate Change (NSECC) to conduct a detailed investigation, coordinate water sampling, and to direct and support remediation of contaminated water supplies. More details can be found in the Communicable Disease Prevention and Control (CDPC) chapter on Legionellosis.

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