Legionnaires Disease-Legionellosis : About

Legionnaires Disease is an infectious disease caused by bacteria belonging to the genus Legionella. More than 90 percent of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in warm environments (25°C to 45°C, with an optimum around 35°C). Legionellosis takes two distinct forms:

  • Legionnaires' disease is the more severe form of the infection and produces pneumonia.
  • Pontiac fever is caused by the same bacterium, but produces a milder respiratory illness without pneumonia which resembles acute influenza.


  • Cough, which may bring up mucus and sometimes blood
  • Shortness of breath
  • Chest pain
  • Fatigue 
  • Loss of appetite
  • Gastrointestinal symptoms, such as nausea, vomiting and diarrhea
  • Confusion or other mental changes