Legionnaires’ disease — also known as Legionella pneumonia, or legionellosis — is a severe form of pneumonia, a respiratory illness that causes the air sacs in the lungs to fill with water or pus.
The Centers for Disease Control and Prevention (CDC) reports that the disease affects about 5,000 Americans each year, with 10 percent of those cases resulting in death. The disease is caught by inhaling water droplets — usually in the form of mist or vapor — that contain Legionella bacteria (Legionella pneumophila). The bacteria are found primarily in human-made, warm-water environments: industrial cooling systems, air conditioners, whirlpool spas, and hot tubs, to name a few. The incubation period — the time between breathing in the bacteria and developing symptoms — is usually 2 to 10 days but can be as much as 16 days.
After Legionnaires’ disease has been diagnosed, hospitalization is often necessary. In the most severe cases of Legionnaires’ disease, complications can include respiratory failure, kidney failure, and septic shock. All of these conditions are very dangerous and can be fatal. It is imperative to monitor conditions closely.