Legionnaires' Disease

ExitCare ImageLegionnaires' disease is a serious lung infection (pneumonia) that is caused by inhaling the Legionella bacteria. This bacteria occurs naturally in the environment and normally does not cause problems. Legionella bacteria grow best in warm water environments. The bacteria can be carried through the air in a mist or vapor (small droplets of water in the air). Once the bacteria enters the lungs, they reproduce rapidly and attack the immune system. People who are at greatest risk for Legionnaires' disease include:

  • Older adults, usually people who are 65 years of age or older.

  • Smokers.

  • People who drink alcohol heavily.

  • People with immune systems weakened from medical conditions such as:

  • Cancer.

  • Kidney failure.

  • HIV.

  • Diabetes.


Inhaling Legionella bacteria is the main cause of developing the disease. It is not contagious (spreading from person to person). The mist carrying the bacteria can travel for miles through the air.

  • Legionella bacteria most often grow in:

  • Air conditioning systems.

  • Public whirlpool spas.

  • Grocery store produce misters.

  • Decorative fountains.

  • Swimming pools.

  • Fitness or physical therapy equipment.

  • Water systems such as pipes, faucets, shower heads in places like hotels, hospitals, or cruise ships.

  • It may also enter the lungs while ingesting contaminated fluids or working with dry, contaminated soil.

  • Legionella bacteria also cause Pontiac fever. This is a milder illness that resembles the flu.


Symptoms may develop 2-14 days after exposure and are similar to other types of pneumonia. Symptoms include:

  • High fever, shaking or chills.

  • Coughing, which may bring up mucous or occasionally bloody mucous.

  • Shortness of breath.

  • Chest pain.

  • Headache.

  • Muscle pain.

  • Tiredness and weakness.

  • Poor appetite.

  • A sickness in your stomach (nausea) or throwing up (vomiting).

  • Confusion.


Legionnaires' disease is diagnosed in a variety of ways.

  • Physical exam.

  • Chest X-ray.

  • Blood tests.

  • Sputum (mucous from the lungs) culture.

  • Urine tests.

  • A Computerized Tomography (CT) scan or lumbar puncture may be done to assess neurological symptoms (confusion) if needed.


  • Hospitalization is often necessary.

  • Antibiotics are the main treatment for Legionnaires' disease and should be given as soon as Legionnaires' disease is suspected.

  • Oxygen may be given.

  • Pontiac fever is mild and does not require specific treatment.


  • Legionnaires' disease is a serious infection and can be life threatening. Taking antibiotics as early as possible is important and effective. If left untreated, Legionnaires' disease can result in serious complications such as:

  • Respiratory failure.

  • Septic shock (A medical condition in which you have very low blood pressure because of an infection).

  • Death.


It may take a few weeks or a few months for your energy level to return after you have had Legionnaires' disease. With proper self-care and medications, you will feel better. Follow your caregiver's instructions as well as these guidelines:

  • Take all medications as directed. Finish the entire course of antibiotics to fight the infection. Report any side effects to your caregiver. Consider taking probiotics to prevent diarrhea.

  • Rest and allow your lungs time to return to their normal function. Gradually resume activity as tolerated.

  • Drink enough water and fluids to keep your urine clear or pale yellow.

  • Ask your doctor for tips on reducing coughing, such as elevating your head and back while sleeping.

  • Follow up with your caregiver as recommended.


  • You develop fever and chills.

  • You develop coughing.

  • You have shortness of breath.

  • You have a headache.

  • You have muscle pain.

  • You develop tiredness and weakness.

  • You have a poor appetite.

  • You feel sick to your stomach (nausea).

  • You are throwing up (vomiting).

  • You develop confusion.


  • You have difficulty breathing.

  • You develop chest pain.

  • You have severe dizziness or lightheadedness.

  • You develop a rapid heartbeat.


  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.


  • Centers for Disease Control (CDC): www.cdc.gov

  • Occupational Safety and Health Administration (OSHA): www.osha.gov