The length of time between exposure to the bacteria and the appearance of symptoms (incubation period) is generally 2–10 days, but can more rarely extend to as long as 20 days. For the general population, among those exposed, between 0.1 and 5.0% develop the<unk> , while among those in hospital, between 0.4 and 14% develop the<unk> . Those with<unk>  usually have fever, chills, and a cough, which may be dry or may produce sputum. Almost all experience fever, while around half have cough with sputum, and one-third cough up blood or bloody sputum. Some also have muscle aches, headache, tiredness, loss of appetite, loss of coordination (ataxia), chest pain, or diarrhea and vomiting. Up to half of those with<unk>  have gastrointestinal symptoms, and almost half have neurological symptoms, including confusion and impaired cognition. "Relative bradycardia" may also be present, which is low to normal heart rate despite the presence of a fever. Laboratory tests may show that kidney functions, liver functions, and electrolyte levels are abnormal, which may include low sodium in the blood. Chest X-rays often show pneumonia with consolidation in the bottom portion of both lungs. Distinguishing<unk>  from other types of pneumonia by symptoms or radiologic findings alone is difficult; other tests are required for definitive diagnosis. People with Pontiac fever, a much milder illness caused by the same bacterium, experience fever and muscle aches without pneumonia. They generally recover in 2–5 days without treatment. For Pontiac fever, the time between exposure and symptoms is generally a few hours to two days.
Legionnaires' disease
Freshers' flu
Lemierre's syndrome
Boutonneuse fever
Scarlet fever
Bartonellosis
Listeriosis
Metal fume fever