Clinical features

There is an incubation period of 2 to 10 days. Possible clinical features include:

• abrupt onset of malaise, headache, myalgia and weakness
• fever with rigor and temperature up to 40 degrees C appear 24 hours later after onset
• cough - initially dry; becomes productive in half of patients; may be haemoptysis
• half of cases develop gastrointestinal symptoms - nausea, vomiting, diarrhoea and abdominal pain
• altered mental status - including confusion, lethargy, disorientation, hallucinations, depression, or coma
• cranial and peripheral neuropathy not uncommon
• crackles and consolidation - but the physical findings are mild compared to the radiological appearances
• haematuria and occasionally, renal failure

Complications may include:

• lung abscess
• empyema
• shock & hypotension
• rhabdomyolysis
• DIC
• TTP
• renal failure

1. Brady MF, Sundareshan V. Legionnaires' Disease. StatPearls Publishing; 2024 Jan.