Cause and exposure
Leptospirosis is a zoonosis caused by Leptospira spirochaetes, acquired through skin/mucosa contact with water or soil contaminated by animal (especially rat) urine. Ask about:
- Occupational exposure — farmers, sewage/abattoir workers, vets
- Recreational freshwater exposure — kayaking, triathlon, swimming
Features
- Biphasic illness: an initial septicaemic phase then an immune phase
- High fever, severe myalgia (classically calf tenderness), headache
- Conjunctival suffusion ("red eyes") — a useful clue
- Severe disease (Weil's): jaundice, acute kidney injury, bleeding, sometimes pulmonary haemorrhage
Investigations
- Bilirubin often high out of proportion to modestly raised transaminases
- AKI, thrombocytopenia, raised CK, neutrophilia
- Confirm with serology (MAT) or PCR
Treatment
- Mild: oral doxycycline (or amoxicillin)
- Severe (Weil's): IV benzylpenicillin or ceftriaxone + supportive care (dialysis for AKI)
- A Jarisch–Herxheimer reaction may follow the first dose
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