Legionellosis
(Legionnaires' disease, Pontiac fever)

What is legionellosis?
Legionellosis is an illness caused by the Legionellae bacteria. Legionellosis can range from a mild respiratory illness to fulminant pneumonia and death.

Who gets the disease?
Legionellosis can anyone but is more common among middle-aged or older men, particularly those who smoke. Persons with other diseases such as cancer, diabetes, chronic lung disease, or those who have problems with their immune system are also at higher risk of getting legionellosis.

How do you get it?
You can get legionellosis through the air by inhaling tiny droplets carrying Legionellae bacteria. The bacteria that cause it can be found in many places in the environment, such as water taps, water tanks, air-conditioning cooling towers, and in contaminated soil at digging sites. Person-to-person spread has not been proven.

What are the symptoms?
The first symptoms of legionellosis can be flu-like, with muscle aches, headache, loss of appetite, tiredness, and dry cough. These symptoms are often followed by chills, diarrhea, and high fever. Temperatures often reach 102 °F or greater, and chest X rays may indicate progressive pneumonia.

When do symptoms start?
The symptoms usually appear 5 or 6 days after exposure to Legionellae bacteria, but the onset can range from 2 to 10 days.

What is the treatment for legionellosis?
A doctor can prescribe antibiotics to treat legionellosis.

How can you keep from getting it?
Because Legionellae bacteria can be found in many places in the environment, there is very little one can do on an individual basis to prevent its occurrence. However, some preventive measures can be taken by industry to reduce the risk of exposures. These measures include the periodic draining and cleaning of cooling towers, and the use of biocides (antibacterial, antifungal agents) to prevent the growth of slime-forming organisms in air conditioning cooling towers and evaporative condensers.