Key points
- Legionnaires' disease and Pontiac fever are two illnesses caused by bacteria called Legionella.
- They present differently in terms of clinical features, symptoms, and complications.
- The organism can be isolated in Legionnaires' disease cases, but not for Pontiac fever.
Clinical features
Legionnaires' disease
Legionnaires' disease is characterized by illness with pneumonia diagnosed radiographically or clinically.
Evidence of clinically compatible disease can be determined from the medical record in several ways:
- Clinical or radiographic diagnosis of pneumonia
- Description of clinical symptoms consistent with a pneumonia diagnosis
Pontiac fever
Pontiac fever is a milder, self-limiting illness without pneumoniaA.
Common signs and symptoms
Legionnaires' disease
Clinical symptoms may vary but include acute onset of lower respiratory illness with fever or coughA. Additional symptoms may be present:
- Chest discomfort
- Headache
- Malaise
- Myalgia
- Nausea, diarrhea, or abdominal pain
- Shortness of breath
Pontiac fever
Symptoms include:
- Chills
- Fatigue
- Fever
- Headaches
- Malaise
- Myalgia
- Nausea or vomiting
- According to the Council of State and Territorial Epidemiologists case definition.
- Egan JR, Hall IM, Lemon DJ, Leach S. Modeling Legionnaires' disease outbreaks: Estimating the timing of an aerosolized release using symptom-onset dates. Epidemiology. 2011;22(2):188–98.
- Fraser DW, Tsai TR, Orenstein W, et al. Legionnaires' disease: Description of an epidemic of pneumonia. N Engl J Med. 1977;297(22):1189–97.
- Glick TH, Gregg MB, Berman B, et al. Pontiac fever. An epidemic of unknown etiology in a health department: Clinical and epidemiologic aspects. Am J Epidemiol. 1978;107(2):149–60.