What is Legionella and Legionnaires’ disease?

Legionella is a type of bacterium which is found naturally in fresh water. Legionnaires’ disease is caused when the legionella bacterium infects the lungs and cause pneumonia. The bacteria can also cause a less serious infection that seems more like a mild case of the flu. That form of legionellosis is commonly called Pontiac fever.

Causes and Common Sources of Growth

Conditions that promote growth of the Legionella organism include heat, sediment, scale, and supporting (commensal) microflora in water. Water sources that frequently provide optimal conditions for growth include:

  • Hot Tubs
  • Cooling Towers (air-conditioning units for large buildings)
  • Hot water tanks
  • Large Plumbing Systems


Exposure and Transmission

In nature, Legionella live in fresh water and rarely cause illness. In man-made settings, Legionella can grow if water is not properly maintained. In general, Legionnaires’ disease is not spread from one person to another. However, this may be possible in rare cases.

Exposure to Legionella may occur by,

  • Breathing in mist or vapor (small droplets of water in the air) containing the bacteria. Ex. breathing in droplets sprayed from a hot tub that has not been properly cleaned and disinfected
  • Aspiration of drinking water. Ex. water “goes down the wrong pipe,” into the trachea (windpipe) and lungs instead of down the digestive tract. 

Safex Can Help

Worried about legionella? Safex offers water and air sampling. Contact us today!

Risk Factors

Certain people are at an increased risk for Legionnaires’ disease. Most healthy people do not get Legionnaires’ disease after being exposed to Legionella. Being 50 years or older or having certain risk factors can increase your chances of getting sick.

These risk factors include:

  • Being a current or former smoker
  • Having chronic lung disease, such as emphysema or chronic obstructive pulmonary disease (COPD)
  • Having a weakened immune system from diseases like cancer, diabetes, or kidney failure
  • Taking medication that weakens your immune system

Symptoms and Treatment

Legionnaires’ disease can cause pneumonia-like symptoms such as:

  • Cough
  • Shortness of breath
  • Muscle aches
  • High fever
  • Headache

Legionnaires’ disease is treated with antibiotics. Most people who get sick need care in a hospital but make a full recovery. If you develop pneumonia symptoms and may have been exposed to Legionella, see a doctor right away. Be sure to mention if you have used a hot tub, spent any nights away from home, or stayed in a hospital in the last two weeks.

For more info, visit www.cdc/gov/legionella.