Legionellosis

Legionellosis is an infection caused by the bacterium Legionella pneumophila. The disease has two distinct forms:

 

1. Legionnaires' disease, the more severe form and includes pneumonia

 

2. Pontiac fever, a milder illness. 

Patients with Legionnaires' disease usually have fever, chills, and a cough, which may be dry or may produce sputum. Some patients also have muscle aches, headache, tiredness, loss of appetite, and, occasionally, diarrhea. Laboratory tests may show that these patients' kidneys are not working properly. Chest X-rays often show pneumonia. It is difficult to tell the difference between Legionnaires' disease and other types of pneumonia by symptoms alone; other tests are required for diagnosis.  

Persons with Pontiac fever have fever and muscle aches and do not have pneumonia. They generally recover in 2 to 5 days without treatment.

The time between the patient's exposure to the bacterium and when they develop symptoms for Legionnaires' disease is 2 to 10 days; for Pontiac fever, it is shorter, generally a few hours to 2 days.

 

Outbreaks of legionellosis have occurred after persons have breathed in mists that come from a water source (e.g., air conditioning cooling towers, whirlpool spas, showers) contaminated with Legionella bacteria. Persons may be exposed to these mists in homes, workplaces, hospitals, or public places. Legionellosis is not passed from person to person, and people have not been known to become infected from auto air conditioners or household window air-conditioning units.

 

• Antibiotics are recommended for treating persons with Legionnaires' disease.

• Pontiac fever requires no specific treatment