What is Legionellosis?

This page was reviewed or revised on Thursday, August 13, 2009.

Legionellosis is an infection caused by the bacteria Legionella pneumophilla. The disease has two distinct forms, Legionnaire's Disease, the more severe form of the infection causing pneumonia, and Pontiac Fever, a milder form of illness. Legionella can cause a very mild respiratory illness or can cause severe pneumonia that can be fatal. Symptoms may include muscle aches, headache, fatigue, fever of >38 Degrees Celcius, chills and dry cough. The time between exposure and onset of illness is 2 to 10 days. Antibiotics are effective in treating the disease.

Legionnaire's Disease acquired its name in 1976 from an outbreak of pneumonia among persons attending a convention of the American Legion members.

How is Legionnella spread?

The Legionella bacteria is spread by breathing in small droplets of water dispersed in the air from air conditioning cooling towers, shower, misters, humidifiers, whirlpool spas etc. It is not spread from person to person. It is also not spread from car or household air conditioning units. Legionella is widely distributed in our environment. It has also been found in ponds and creeks. Legionella reproduce to high numbers in warm stagnant water.

The disease is more serious in middle-aged or older men, particularly those who smoke or have chronic lung disease, diabetes, mellitus and kidney failure. Also at risk are people whose immune system is suppressed.

How do you prevent Legionella?

• Legionella is susceptible to heat. Water temperature in hot water holding tanks should be raised to 60 Degrees Celcius or tanks be drained and cleaned to remove sediment and scale.
  
• Cooling towers, humidifiers, air handling units, floor drains and other stagnant water sources should be drained, cleaned and disinfected.
  
• Develop a schedule for removing, cleaning and disinfecting showerheads and all equipment that generate water droplets.
  
• Install high efficiency filters on ventilation intakes.