Legionnaire's Disease
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Legionnaire's Disease

(Legionnaire's Pneumonia; )

En Español (Spanish Version)

Definition

Legionnaire's disease is a form of pneumonia , or lung infection. It got its name after the disease struck at the American Legionnaires Convention in 1976.

Causes

Legionnaire's disease is caused by the bacterium Legionella pneumophilia . The bacteria are most often found in sources of standing water, such as cooling towers, HVAC systems, and air conditioners, as well as in soil.

Legionnaire's disease can be contracted by:

  • Breathing water vapor from a standing water source that contains Legionella bacteria into the lungs
  • Breathing dust from soil containing Legionella bacteria into the lungs

The Lungs

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Person-to-person transmission does not occur.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Risk factors for Legionnaire's disease include:

  • Advanced age
  • Sex: male
  • Smoking
  • Excessive alcohol intake
  • Chronic lung disease
  • Weakened immune system (as with AIDS )
  • People with kidney failure
  • Diabetes
  • Taking cortisone or other immunosuppressive drugs
  • Organ transplant patients
  • Working with soil, especially newly tilled soil or potting soil

Symptoms

Symptoms may include:

  • Fatigue
  • Fever (often high)
  • Chills and muscle aches
  • Dry cough
  • Chest pain with coughing or breathing
  • Loss of appetite
  • Headache

Symptoms that develop if the infection becomes serious include:

  • Shortness of breath
  • Abdominal pain
  • Nausea, vomiting, or diarrhea
  • Mental problems, confusion, or memory loss

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include:

  • Blood tests—These tests look for high or rising antibodies to Legionella bacteria.
  • Sputum tests—The mucus from deep inside your lungs is stained or cultured, in an effort to identify the cause of the infection.
  • Kidney function tests—Poor kidney function is often seen in Legionella infected patients.
  • Urine tests—These tests check for Legionella proteins in the urine.
  • Chest x-ray —X-rays help diagnose pneumonia or lung infection.

Treatment

Legionnaire's disease is usually treated with antibiotics. Quinolones, macrolides (such as azithromycin, clarithromycin, or erythromycin), or tetracycline are commonly prescribed. In severe cases, a drug called rifampin may be given. Initial therapy may be given by vein.

Prevention

Proper design, maintenance, and cleaning of standing water sources, such cooling towers, plumbing systems, HVAC systems, and air conditioners, can reduce the risk of spreading Legionnaire's disease.

You can reduce your risk of getting Legionnaire's disease by:

  • Not smoking
  • Limiting the amount of alcohol you drink
  • If you work with freshly tilled soil or potting soil:
    • Wear gloves and a mask.
    • Don't inhale dust from the soil.
    • Moisten the soil to lower the amount of dust.

RESOURCES:

Centers for Disease Control and Prevention (CDC)
http://www.cdc.gov

National Institute of Environmental Health Sciences
National Institutes of Health (NIH)
http://www.niehs.nih.gov

CANADIAN RESOURCES:

Capital Health
http://www.cdha.nshealth.ca/

Communicable Disease Control Unit
http://www.gov.mb.ca/health/publichealth/cdc/index.html

References:

Arcavi L, Benowitz NL. Cigarette smoking and infection. Arch Intern Med. 2004;164:2206-2216.

Beers MH, Berkow R. The Merck Manual of Diagnosis and Therapy. 17th ed. Hoboken, NJ: John Wiley & Sons; 1999.

Canadian Center for Occupational Health and Safety website. Available at: http://www.ccohs.ca/ . Accessed October 11, 2005.

National Center for Infectious Diseases website. Available at: http://www.cdc.gov/ncidod/ . Accessed October 11, 2005.

Principles and Practice of Infectious Diseases. 6th ed. Churchill Livingstone Inc; 2005.



Last reviewed October 2007 by David L. Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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