Legionellosis is an infection caused by the bacteria Legionella pneumophila. This bacterium can be found in water and grows best in hot tubs, plumbing systems, and shallow fountains. Legionella is not spread human to human, but is spread by inhalation of water droplets containing the bacteria. Transmission often occurs when a spray can, humidifier or a water system involved with air conditioning are contaminated. Most individuals who inhale Legionella don’t develop symptoms of infection because the immune system can destroy the bacteria. Those who are at risk for infection are older people, those with pre-existing lung diseases, and those with weakened immune systems.
Symptoms of legionellosis include a high fever, headache, shortness of breath, coughing, muscle aches, confusion, and lack of energy. There are two conditions associated with Legionella infection: Legionnaire’s disease and Pontiac fever. Legionnaire’s disease is a lung infection (pneumonia) with symptoms beginning anywhere from two days to two weeks from the time of infection. Pontiac fever has the same symptoms as Legionnaire’s disease but lasts for two to five days and resolves without treatment. Unlike Legionnaire’s disease, Pontiac fever does not cause pneumonia.
Diagnosis of Legionnaire’s disease can be made using a urine antigen test to detect the bacteria in the urine, growing the bacteria in a culture dish to identify it from the body, and using blood tests. An X-ray and physical exam are used to diagnose pneumonia. Legionnaire’s disease is usually treated with antibiotics. If you have been diagnosed with legionellosis, talk to your doctor about the most current treatment options.