Legionnaires’ disease is transmitted by inhalation of aerosolized water and/or soil contaminated with the bacteria. It is not transmitted from person-to-person. Sources where temperatures allow the bacteria to thrive include hot-water tanks, hot tubs, cooling towers and evaporative condensers of large air-conditioning systems, such as those commonly found in hotels and large office buildings.
There are several common ways people are exposed to the bacteria:
- LD caused by inhalation of aerosolized droplets
- Aspiration or choking of bacteria contaminated drinking water
- The organism is commonly thought to be present in man-made aquatic environments
- Some studies have estimated up to 70% of plumbing systems are estimated to be contaminated by Legionellae.
Exposure to the bacteria can cause Legionnaires’ disease. Patients with Legionnaires’ disease usually have fever, chills, and a cough, which may be dry or may produce sputum. Some patients also have muscle aches, headache, tiredness, loss of appetite, loss of coordination (ataxia), and occasionally diarrhea and vomiting. Confusion and impaired cognition may also occur, as can a so-called ‘relative bradycardia’, i.e. low or low normal heart rate despite the presence of a fever. Laboratory tests may demonstrate significant extra-pulmonary manifestations including abnormalities in the patients’ renal functions, liver functions and electrolytes with derangements, including hyponatremia. Chest X-rays often show pneumonia with bi-basal consolidation. It is difficult to distinguish Legionnaires’ disease from other types of pneumonia by symptoms or radiologic findings alone; other tests are required for diagnosis.
For more information, contact the Cogency TEAM.