Leptospirosis
Leptospirosis is a zoonotic spirochetal infection from water or soil contaminated with infected-animal urine, causing a biphasic illness with conjunctival suffusion and calf/lumbar myalgia, occasionally progressing to Weil disease with jaundice and renal failure, diagnosed clinically and confirmed by culture, serology, or PCR, and treated with doxycycline or, in severe disease, IV penicillin or ceftriaxone.
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What this article covers
- Overview
A zoonotic infection caused by the spirochete Leptospira interrogans, acquired through contact with fresh water, soil, or food contaminated with the urine of infected animals, chiefly rodents, dogs, and livestock.
- Epidemiology
Worldwide distribution with the highest incidence in tropical and subtropical regions with heavy rainfall, where warm, wet conditions favor organism survival in soil and water and outbreaks cluster after flooding.
- Risk factors
Recreational freshwater activity (swimming, surfing, kayaking, wading) in warm climates, especially after heavy rain or flooding.
- Pathophysiology
Leptospira interrogans is a thin, tightly coiled spirochete with characteristic hook-shaped ends, motile via axial filaments, that penetrates intact mucous membranes or broken skin after contact with…
- Clinical features
The hallmark early findings are abrupt-onset high fever with severe headache (present in about 98% of patients) and conjunctival suffusion, erythema of the conjunctivae without a purulent discharge, which is a strong clue to the diagnosis.
- Differential diagnosis
Dengue: shares fever, myalgia, and headache in a returning traveler but produces retro-orbital pain, a positive tourniquet test, and thrombocytopenia with a positive dengue NS1 antigen or serology…
- Diagnosis
Leptospirosis is diagnosed clinically in a patient with a compatible exposure history (freshwater or animal-contaminated soil contact) and the biphasic pattern of abrupt fever, severe headache…
- Management
First, classify severity: for mild to moderate (anicteric) disease that does not require hospitalization, treat with oral outpatient antibiotics, and reserve hospitalization and IV antibiotics for icteric or otherwise severe (Weil) disease.
- Complications
Weil disease (icterohemorrhagic leptospirosis): the combination of jaundice, acute kidney injury, and hemorrhagic manifestations, carrying the highest mortality risk.
- Prognosis
The majority of infections (roughly 90%) are mild, anicteric, and self-limited, resolving without long-term sequelae even without specific antibiotic therapy, though treatment shortens illness duration.
- Prevention
Doxycycline prophylaxis, 200 mg PO once weekly, starting shortly before and continued during a defined period of high-risk exposure, is recommended for short-term travelers or workers with…
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