Legionella Tests Test
Legionella tests look for Legionella bacteria in urine, sputum, or lung tissue. They help diagnose Legionnaires' disease, a severe form of pneumonia. A blood test can check for past exposure but cannot diagnose an active infection.
What this test measures
Legionella tests measure the presence of Legionella bacteria in urine, sputum, or lung tissue. They help diagnose Legionnaires' disease, a severe pneumonia caused by these bacteria.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
If your results were positive, it probably means you have Legionnaires' disease.
Lower-than-normal results
If your results were negative, it may mean you have a different type of infection. It may also mean not enough Legionella bacteria were found in your sample.
Frequently asked questions
What are Legionella tests used for?
They are used to find out whether you have Legionnaires' disease.
How do you get Legionella infection?
You breathe in mist or small drops of water that contain the bacteria. You usually can't get it from drinking water unless you accidentally breathe it into your lungs.
Can Legionella spread from person to person?
No, the bacteria do not spread from person to person.
Who is at higher risk for Legionella infection?
People over 50, current or former smokers, those with chronic diseases like diabetes or COPD, and people with weakened immune systems are at higher risk.
What does a positive Legionella test mean?
A positive result probably means you have Legionnaires' disease.
Related lab tests
Sources
- MedlinePlus: Legionella Tests — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.