Legionnaires’ disease, also known as legionellosis, is an infectious disease that affects up to 20,000 people in the United States each year. Some people can be infected with the Legionella bacterium and have only mild symptoms or no illness at all. The fatality rate of Legionnaires’ disease has ranged from 5 to 30% during various outbreaks. Common symptoms can include: shortness of breath, productive cough, diarrhea, high fevers, weakness, body aches, headaches, nausea, and vomiting. The disease is generally treated with wide-range antibiotics, inhalers, as well as various over-the-counter medications, depending on the patient’s symptoms.

Legionellosis normally is contracted when aerosolized water containing Legionella bacteria is breathed into the lungs. Small water droplets containing the bacteria are inhaled into the body. Potential sources of such contaminated water include cooling towers used in industrial water systems as well as in large central air conditioning systems, evaporative coolers, hot water systems, showers, whirlpool spas, architectural fountains, room-air humidifiers, ice making machines, misting equipment, and similar outlets that draw upon a public water supply.  Freshwater ponds, creeks, and ornamental fountains are also potential sources of Legionella. The disease is particularly associated with hotels, cruise ships and hospitals–especially those with old or poorly maintained pipework and cooling systems.