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Alternative Names Return to topLegionella pneumonia; Pontiac fever
Definition Return to top
Legionnaire's disease is an acute respiratory infection caused by Legionella bacteria.
Causes Return to top
The bacteria that cause Legionnaire's disease have been found in water delivery systems. They can survive in the warm, moist, air conditioning systems of large buildings, including hospitals.
Most cases are caused by Legionella pneumophila. The rest of the cases are caused by other Legionella species.
Spread of the bacteria from person to person has not been proven.
Most infections occur in middle-aged or older people, although they have been reported in children. Typically, the disease is less severe in children.
Risk factors include:
Symptoms Return to top
Symptoms tend to get worse during the first 4 - 6 days. They typically improve in another 4 - 5 days.
Symptoms may include:
Exams and Tests Return to top
The health care provider will perform a physical exam, and may hear abnormal sounds called crackles when listening to the chest with a stethoscope.
Tests that may be done include:
Treatment Return to top
Antibiotics are used to fight the infection. Treatment is started as soon as Legionnaire's disease is suspected, without waiting for confirmation by lab test.
Antibiotics commonly used to treat this condition include:
Other treatments may include:
Outlook (Prognosis) Return to top
Legionnaire's disease can be life-threatening. The death rate is higher in patients with other diseases. The death rate for patients who develop Legionnaire's disease while in the hospital is close to 50%, especially when antibiotics are started late.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Make an appointment with your health care provider if you have any type of breathing problem.
Prevention Return to top
Treating contaminated water delivery systems can prevent the spread of disease.
References Return to top
Edelstein PH. Legionella infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 335.Update Date: 3/17/2009 Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.