About Legionellosis (Legionella)
Minnesota Department of Health
Revised 3/2013
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Legionellosis
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What is Legionnaires’ disease?
What are the symptoms?
How is it spread?
Who is at risk?
How is it diagnosed?
How is it treated?
What is Legionnaires’ disease?
- Legionnaires’ disease is an infection caused by the bacteria Legionella pneumophila, which is found in water.
- Legionnaires’ disease was named for the first recognized outbreak at a 1976 convention of the American Legion in Philadelphia.
What are the symptoms?
- Symptoms include:
- muscle aches
- headache
- fatigue
- loss of appetite
- and coughing
- These symptoms are followed by high fever (102-105°F), pneumonia, and occasionally abdominal pain and diarrhea.
How is it spread?
- Legionnaires’ disease is spread by inhaling the fine spray (aerosols) from water sources containing Legionella bacteria.
- Persons can be exposed to these aerosols in their homes, at work, in hospitals, or in other public places.
- Legionella organisms are found in many types of water systems and reproduce in high numbers in warm water (95-115oF), such as certain plumbing systems, hot water tanks, cooling towers, large air conditioning systems, and whirlpool spas.
- Legionnaires’ disease is not spread from person to person.
Who is at risk?
- Legionnaires’ disease occurs worldwide, especially in persons over 50 years of age.
- Other risk factors include smoking, male gender, chronic lung disease, suppressed or weakened immune system due to organ transplant, cancer, kidney disease, or AIDS.
How is it diagnosed?
- Diagnosis of Legionnaires’ disease requires testing for Legionella bacteria, something that is not usually done on persons who present at the hospital with fever and pneumonia.
- As a result, Legionnaires’ disease often goes undiagnosed.
- A urine antigen test is the most common type of test used to diagnose Legionnaires’ disease.
- This test detects the presence of Legionella antigen in urine.
How is it treated?
- Most cases can be successfully treated with antibiotics. The case fatality rate is generally 5-30%.
