A progressive and potentially fatal atypical pneumonia caused by the inhalation of water aerosols containing Legionella bacteria.
caused by infection with a gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between 25 and 45 °C.
- Legionnaires’ disease, “Legion Fever” , 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.
Manifestation: Signs and Symptoms:
- cough, which may be dry or productive
- muscle aches
- loss of appetite (anorexia)
- loss of coordination (ataxia)
- occasionally diarrhea and vomiting.
- Laboratory tests may show that patients’ renal functions, liver functions and electrolytes are deranged
- 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.
Chest X-ray of pneumonia patient
- quinolones (levofloxacin, moxifloxacin, gemifloxacin)
- macrolides (azithromycin, clarithromycin, roxithromycin).
- Rifampicin can be used in combination with a quinolone or macrolide
- The antibiotics used most frequently used are levofloxacin and azithromycin
- Persons with Pontiac fever experience fever and muscle aches without pneumonia. They generally recover in 2 to 5 days without treatment.
- The time between the patient’s exposure to the bacterium and the onset of illness for Legionnaires’ disease is 2 to 10 days; recovery duration is longer with the additional use of antibiotics.