Legionella is a type of bacteria . When it affects your lungs, it can cause a severe form of pneumonia known as Legionnaires' disease . Legionella tests look for these bacteria in urine or sputum. A blood test may be done to check if you have been exposed to the bacteria, but it cannot diagnose a Legionella infection.
Legionnaires' disease has similar symptoms to some types of pneumonia, but it can also cause diarrhea and confusion. Legionella bacteria can also cause Pontiac fever, a milder, flu-like illness that doesn't infect your lungs. Together, Legionnaires' disease and Pontiac fever are known as legionellosis.
Legionella bacteria are found naturally in freshwater environments. But the bacteria can make people sick when it grows and spreads in man-made water systems. These types of systems include plumbing systems of large buildings, including hotels, hospitals, nursing homes, and cruise ships. The bacteria may then contaminate water sources, such as hot tubs, fountains, and air-conditioning systems.
Legionellosis infections happen when people breathe in mist or small drops of water that contain the bacteria. You usually can't get the infection through drinking the water, unless you aspirate it (accidentally breathe the water into your lungs) The bacteria do not spread from person to person. But there can be a disease outbreak if many people are exposed to the same contaminated water source.
Not everyone who is exposed to Legionella bacteria will get sick. You are more likely to develop an infection if you:
- Are over the age of 50
- Are a current or former smoker
- Have a chronic disease such as diabetes or kidney failure
- Have a chronic lung disease such as COPD or emphysema
- Have a weakened immune system due to a disease such as HIV or cancer, or are taking medicines that suppress the immune system
- Live in a long-term care facility
- Have recently stayed in a hospital or had surgery requiring anesthesia
Pontiac fever usually clears up on its own, but Legionnaires' disease can be fatal if not treated. Most people will recover if promptly treated with antibiotics .
Other names: Legionnaires' disease testing, Legionellosis testing, Legionella pneumophila