Legionnaire's disease

Legionnaire's Pneumonia, Legionellosis

What is Legionnaire's disease?

Legionnaire's disease is a type of pneumonia caused by bacteria that dwell in man-made and natural aquatic environments. The bacteria have been isolated from diverse areas such as plumbing systems, air conditioners, humidifiers, hot tubs, whirlpools, ice machines, and potable water systems. The disease was first diagnosed in 1976 when 221 delegates to an American Legion conference held in Philadelphia developed pneumonia and 34 died from a then-unknown agent. Though it is considered an infectious illness, Legionnaire's disease is not spread from person to person, but rather through contaminated water or ventilation systems. It is one of the most common types of community acquired pneumonia, and usually strikes smokers, the elderly, diabetics, alcoholics, and individuals who have lung problems or a low resistance to disease. ales outnumber females three to one in numbers infected. Reports of the disease are most common in summer and fall.

How is it diagnosed?

Symptoms of Legionnaire's Disease

Individuals complain of high fever, chills, headaches, muscle aches, chest pain, a dry cough, weakness and shortness of breath. As the disease progresses, they may complain of abdominal pain and diarrhea.

Physical exam The physical findings include high fever, slow pulse (bradycardia), severe pneumonia, and altered mental status.

Tests may include chest x-ray and serologic blood testing. The white blood count will be elevated (leukocytosis). A urine specimen and lung fluid sample will be examined for signs of the disease. Because the bacterium does not show up in ordinary sputum cultures, a special sputum culture or stain test will be necessary.

How is Legionnaire's disease treated?

Hospitalization is often required, during which time the individual is given erythromycin, an antibiotic intravenously for several days. Some individuals require supplemental oxygen during this time. After the individual stabilizes, oral antibiotic therapy must be continued for an additional fourteen to twenty-one days.


  • Antibiotics. Be sure to finish all prescribed medication.
  • If the cough is painful and doesn’t produce sputum, you may use non-prescription medicine to suppress it. If the cough produces sputum, don’t suppress it.
  • You may take aspirin or acetaminophen to reduce fever.
Information Brand Generic Label Rating
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https://medtips.org/a/azithromycin.html Zithromax Azithromycin Off-Label
https://medtips.org/c/ciprofloxacin.html Cipro Ciprofloxacin Off-Label
Order Levaquin 750mg Levaquin Levofloxacin Off-Label
Co-trimoxazole Bactrim Co-trimoxazole Off-Label

Sumycin (Tetracycline), Doryx (Doxycycline), Ilosone (Erythromycin), Biaxin (Clarithromycin), Noroxin (Norfloxacin)

What might complicate it?

Complications include lung abscess, respiratory failure, low blood pressure, shock, and kidney failure. In addition, any underlying lung disease or immunological problems may make Legionnaire's disease more resistant to treatment.

Predicted outcome

Most individuals recover from Legionnaire's Disease if it is diagnosed early enough. However, some outbreaks have had mortality rates between fifteen and twenty percent. Roughly one-quarter of individuals who are immunodeficient die.


Some symptoms of Legionnaire's disease are identical to those of pulmonary embolism.

Appropriate specialists

Internist and lung specialist.

Notify your physician if

  • You or a family member has symptoms of Legionnaire's disease.
  • The following occur during or after treatment:
    • Temperature spike to 102°F (38.9° C).
    • Severe chest pain, despite treatment.
    • Increased shortness of breath.
    • Dark or bluish nails, lips or skin.
    • Blood in the sputum.

Last updated 19 December 2015


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