Legionnaires’ Disease

Urine (pee) and sputum (mucus or phlegm) tests are the most common ways to diagnose Legionnaires’ disease. Your healthcare provider will also get pictures of the inside of your chest with an X-ray or CT scan.

Your healthcare provider will perform a physical exam and ask you about your health and travel history.

What tests will be done to diagnose this condition?

Tests to look for signs of Legionella bacteria and imaging are done to diagnose Legionnaires’ disease. These include:

• Urine or sputum tests: You’ll pee in a cup (urine test) or cough and spit in a tube (sputum test). Your healthcare provider will test your pee or mucus for signs of Legionella.
• Blood tests: Your provider will take blood from your arm with a needle. Your healthcare provider will look for signs of Legionella in your blood. They can also use blood tests to understand how well your organs are working.
• Imagining (chest X-ray or CT scan): Your provider will use a machine to take pictures of your lungs. They can use these images to look for changes in your lungs, like pneumonia.
• Bronchoscopy: Your provider may use a thin, lighted tube to look at the inside of your lungs. They’ll take samples to be tested for signs of Legionella.
• Thoracentesis: You may need to have fluid drained from the outside of your lungs (thoracentesis). Your provider will test this fluid for signs of Legionella.

How do you know if you have Legionnaires’ disease?

The only way to know if you have an infection with Legionella is to be diagnosed by a healthcare professional. Legionnaires’ disease has symptoms of pneumonia, plus diarrhea and mental changes, like confusion.