What is the Difference Between Legionella and Legionnaires Disease?

Legionella is a bacterium that can cause two distinct clinical entities: Legionnaires' disease and Pontiac fever. Both diseases are caused by exposure to Legionella bacteria, specifically Legionella pneumophila.

Legionnaires' Disease is a severe form of pneumonia (lung inflammation) usually caused by infection with Legionella bacteria. It is particularly susceptible to older adults, smokers, and people with weakened immune systems. Symptoms of Legionnaires' disease include fever, headache, muscle aches, cough that might bring up mucus and sometimes blood, and other respiratory symptoms. If left untreated, Legionnaires' disease can be fatal, but prompt treatment with antibiotics usually cures it.

Pontiac Fever is a milder illness that resembles the flu. It is also caused by exposure to Legionella bacteria but typically resolves on its own without treatment.

Both diseases are contracted by inhaling the bacteria from water or soil. Legionnaires' disease can be a significant public health concern, especially in hospitals and nursing homes, where germs can spread easily and people are more vulnerable to infection.

Comparative Table: Legionella vs Legionnaires Disease

Here is a table comparing Legionella and Legionnaires' disease:

Legionella is a genus of bacteria that can cause Legionnaires' disease, an acute pneumonic illness. Legionella is found in water systems, and transmission occurs when aerosols containing the bacteria are inhaled. Legionellosis is a nationally notifiable disease, and cases must be reported to local or state health departments.