Diagnosis

Legionnaires' disease is similar to other types of pneumonia. To help identify the presence of legionella bacteria quickly, your doctor might use a test that checks your urine for legionella antigens — foreign substances that trigger an immune system response. Other tests might include:

• Blood and urine tests
• Chest X-ray, which doesn't confirm Legionnaires' disease but can show the extent of infection in your lungs
• Tests on a sample of your sputum or lung tissue