Legionnaires’ Disease (Legionella)


What is Legionnaires’ Disease and where is it found?

Legionnaires’ disease is caused by a type of bacteria called Legionella pneumophila. Legionella bacteria are found naturally in the environment usually in water. The bacteria grows best in warm water and have been found in air conditioning cooling towers, evaporative condensers, whirlpool spas, humidifiers, respiratory therapy devices, ponds and soil from their banks, decorative fountains and potable water systems.  People get Legionnaires’ disease when they breathe in air that contains the bacteria.


What are the symptoms of Legionnaires’ Disease?

Legionnaires’ disease is a common cause of pneumonia. Symptoms include high fever, chills, cough, muscle aches and headaches. Some people may also get abdominal pain and diarrhea. Symptoms usually begin 2 to 14 days after being exposed to the bacteria.


Who is at risk?

Those 50 years of age and older are at greater risk for developing Legionnaires’ disease.  Smokers, individuals with chronic diseases (chronic lung disease, renal disease, diabetes) and those with weakened immune systems are also at risk.


How is Legionnaires’ Disease spread?

Legionnaires’ disease does not spread from person to person. To get infected, you must breathe in contaminated droplets from a source of Legionella bacteria. A person diagnosed with Legionnaires’ disease in the community or workplace is not a threat to others.


How is Legionnaires’ Disease treated?

Most cases can be successfully treated with antibiotics. Healthy people usually recover from the infection. Older people and those with underlying medical problems who are not able to fight the infection as easily often take longer to recover.


What is Pontiac Fever?

Pontiac Fever is a mild form of illness caused by the same bacteria as Legionnaires’ disease (Legionella pneumophial). Symptoms are similar but milder and the illness does not progress to pneumonia. Pontiac Fever usually lasts 2 to 5 days and does not require treatment.


This page provides basic information only. It must not take the place of medical advice, diagnosis or treatment. Always talk to a health care professional about any health concerns.


For Further Information

Call the Infectious Disease Program: (807) 625-5900

or toll-free 1-888-294-6630

Health Topic
Diseases & Infections