Legionnaires’ disease is caused by Legionella bacteria. It can cause serious and potentially fatal pneumonia. Legionella bacteria are found naturally in the environment, usually in water. It grows best in warm water such as hot tubs, cooling towers, hot water tanks, and industrial or commercial water systems. If not discovered and removed from these man-made environments, there is a greater risk of human infection. People get the disease by breathing in droplets of mist or vapor that contain the bacteria. The more bacteria in the droplets or mist, the greater the risk of infection. The most susceptible individuals are the very young, the old, smokers, and anyone with lung disease or a compromised immune system. It is not transmitted from person to person. Symptoms begin two to 14 days after exposure and include cough, shortness of breath, high fever, aches, and diarrhea. Hospitalization is common. Proper diagnosis is essential so the proper antibiotics and other treatments can be given. The fatality rate can be as great as 30 percent.
Testing: The fastest test is a Legionella urine antigen test. It has a high degree of specificity. If positive, sputum cultures can be used as further confirmation. Blood tests can also be performed.