Health Topics

Legionnaires’ Disease

Legionnaires’ disease is a type of pneumonia caused by Legionella bacteria.

Legionella bacteria are found mainly in water, but also in soil. They grow best in warmer temperatures and prefer to live in a slime layer on the inside of pipes in warm waterlines, reservoirs or tanks that are not used often or stagnant.

To get Legionnaires’ disease:

  • You must inhale small droplets of water that contain Legionella bacteria
  • Legionella bacteria must be present in large numbers in the water
  • You usually have personal health risk factors such as a weakened immune system

Legionnaires’ disease is not contagious.

Legionella bacteria might be in:

  • Shower heads
  • Faucets
  • Whirlpools
  • Decorative fountains
  • Dehumidifiers
  • Filtered water
  • Fish tanks
  • Hot tubs
  • Hot water tanks
  • Humidifiers
  • Ponds
  • Saunas
  • Spray bottles
  • Steam tables
  • Therapy tubs
  • Cooling towers

If Legionella bacteria are in your water system at home, the risk of getting Legionnaires’ disease is extremely low if you do not have another serious illness.  Legionnaires’ disease occurs more often in people age 50 or older and people with weakened immune systems such as organ transplant patients and people with lung conditions, cancer, diabetes and smokers.

Symptoms usually start two to 14 days after you are exposed to Legionella bacteria.  

Symptoms of Legionnaires’ disease can include:

  • Fever
  • Chills
  • Cough
  • Shortness of breath
  • Muscle pains
  • Headache
  • Tiredness
  • Loss of appetite
  • Diarrhea
  • Pneumonia

The initial symptoms for Pontiac Fever, another illness caused by Legionella bacteria, are similar; however, people recover from Pontiac Fever within two to five days without treatment.

Most people with Legionnaires’ disease have pneumonia, a lung infection.  Pneumonia is confirmed with a chest x-ray or physical exam.  Lab tests using urine (pee), blood or phlegm are used to diagnose Legionnaires’ disease.

Legionnaires’ disease is treated with antibiotics. Treatment is most successful for healthy people. People with weakened immune systems may not be able to fight the infection as well. 

The key to preventing Legionnaires’ disease is maintaining the water systems where Legionella grow.  In your home, you should properly maintain all mist-producing devices, such as showerheads, hot tubs, whirlpools and humidifiers. Make sure you clean and disinfect these devices regularly according to the manufacturers' directions.

Legionella bacteria that cause Legionnaires’ disease are naturally present in dirt or soil, and can get into hot tubs on your feet.  Legionella bacteria grow if they get into a poorly maintained hot tub.  They are then inhaled through the fine water spray or mist to cause Legionnaires’ disease in people.  Hot tub water temperatures between 20 and 46 C (68 to 113 F) are ideal for Legionella bacteria growth. 

Prevent Legionella bacteria growth in your hot tub

Here are some safety tips to follow for your hot tub:

  • Buy a test kit for pH.
  • Check the disinfectant and pH levels before each use.
  • Maintain these disinfectant levels:
    • Chlorine 3 ppm
    • Bromine 5 ppm
  • Maintain the water pH between 7.2 and 7.8.
  • Consult your hot tub dealer for help with water chemistry problems or to have an advanced chemical analysis of your water.
  • “Shock” the hot tub water regularly by adding pool shock chemicals, following instructions in your hot tub manual or hot tub dealer instructions. 
  • Do not get in your hot tub until chemical levels are normal.
  • Clean or replace filters according to your hot tub instruction manual.
  • Ensure your hot tub circulates the water periodically when it is not in use to keep the water disinfected.
  • Scrub hot tub surfaces, including the hot tub cover, to remove any slime.
  • Cover and lock your hot tub when it is not in use.
  • Use and store hot tub chemicals safely.  Follow instructions on the product labels and safety data sheets.

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