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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Leptospirosis

Infectious diseases, microbiology and sexual health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Weil disease or pulmonary haemorrhage

Jaundice with acute kidney injury, shock, bleeding, meningism, myocarditis, hypoxaemia, haemoptysis or diffuse alveolar infiltrates after animal or contaminated-water exposure indicates severe multisystem leptospirosis.

Action: Use ABCDE, obtain cultures and UKHSA blood and urine samples, start intravenous antibacterial treatment without awaiting confirmation, involve infection and critical care, and provide cautious haemodynamic, renal, respiratory and bleeding support.

Synopsis

Recognise leptospirosis after animal-urine or freshwater exposure, detect Weil disease and pulmonary haemorrhage early, select time-dependent reference tests, and begin severity-appropriate antibiotics and organ support.

  • Pathogenic Leptospira are shed in urine from rats, mice, cattle, pigs, dogs and other animals, contaminating freshwater, mud, soil and occupational environments.
  • Organisms enter through cuts, softened skin or conjunctival and oral mucosa; kayaking, open-water swimming, flooding, sewage work, farming and animal-tissue contact are typical risks.
  • Acute leptospirosis causes fever, severe headache, prominent calf or lower-back myalgia, nausea and conjunctival suffusion without purulent discharge.
  • Severe Weil disease combines jaundice, acute kidney injury and haemorrhagic features; pulmonary haemorrhage, aseptic meningitis, myocarditis and shock can occur with or without marked jaundice.
  • First-line assessment includes FBC, renal and liver profiles, CK, urinalysis, coagulation, ECG and chest imaging when indicated, plus blood cultures and malaria tests after travel.
  • Send blood and urine with exact illness and exposure dates to UKHSA RIPL; blood PCR performs best early, while urine often remains PCR-positive later.
  • IgM supports recent infection after antibodies emerge, but cross-reaction and persistence limit specificity; paired serology or microscopic agglutination testing can resolve uncertainty.
  • For suitable non-severe adult disease, doxycycline 100 mg orally twice daily for five to seven days is a commonly used early regimen.
  • For severe adult disease, intravenous benzylpenicillin 1.2 g every six hours for five to seven days is an established option; ceftriaxone is a specialist-selected alternative.
  • Leptospira interrogans is laboratory-notifiable in England; report clusters or other significant hazards to health protection without confusing laboratory duty with the clinician disease list.

Key red flags

Jaundice with oliguria or rising creatinine is classic severe Weil disease and requires admission even when aminotransferase elevation is modest.

Haemoptysis, falling haemoglobin, new hypoxaemia or bilateral infiltrates may be diffuse pulmonary haemorrhage and can progress to respiratory failure rapidly.

Shock, arrhythmia, chest pain or disproportionate tachycardia may indicate myocarditis, vasoplegia or major haemorrhage.

Severe headache, photophobia, neck stiffness, confusion or focal signs requires a meningitis and encephalitis pathway alongside leptospiral testing.

Pregnancy after a compatible exposure needs urgent obstetric and infection review because maternal infection can cause fetal loss and preterm birth.

Treatment should not wait for PCR or seroconversion when the exposure and severe syndrome are convincing; direct detection is time sensitive.

Weil triad

Jaundice, acute kidney injury and haemorrhagic tendency identify severe multisystem disease rather than uncomplicated viral-like illness.

Pulmonary haemorrhage

Cough, dyspnoea, haemoptysis, falling haemoglobin and diffuse infiltrates indicate alveolar capillary bleeding with high mortality.

Aseptic meningitis

Headache, photophobia, neck stiffness and lymphocytic cerebrospinal-fluid inflammation can arise during the immune phase.

Investigation priorities

01
First-line organ severity panelFirst stepFirst line

Identify kidney, liver, muscle, haematological and coagulation injury at presentation.

Management branches

SUSPECTLink exposure to syndrome

Acute fever follows freshwater, floodwater, sewage, rodent, livestock or animal-tissue exposure.

  1. Record exposure date, skin breaks, immersion, occupation, country, animal species and protective equipment, then ask about calf pain, red eyes, urine, jaundice, bleeding and breathing.
  2. Perform ABCDE and an organ-focused examination, obtaining bedside glucose, urine output, blood tests, urinalysis, ECG and chest assessment before classifying severity.
  3. Send blood and urine to RIPL with exact onset date, plus cultures, malaria films and alternative infection tests selected from the wider epidemiology.
  4. Start antibiotics when clinical suspicion is significant, particularly early or severe illness, rather than awaiting serology or reference confirmation.
MILDTreat stable early disease

A suitable adult has a compatible mild syndrome, reliable oral intake and no renal, hepatic, pulmonary, neurological, cardiac or obstetric red flag.

  1. Give doxycycline 100 mg orally twice daily for five to seven days after checking pregnancy, age, allergy, interactions and ability to take it correctly.
  2. Use a locally approved alternative after infection or microbiology advice when doxycycline is unsuitable, particularly during pregnancy.

Key medicines

DoxycyclineGive 100 mg orally twice daily for five to seven days for suitable non-severe adult leptospirosis, beginning promptly when clinical suspicion is strong.Avoid routinely in pregnancy and children under 12 years, counsel on photosensitivity and oesophagitis, separate from cations and escalate immediately if jaundice, oliguria or respiratory signs emerge.
Intravenous benzylpenicillinGive 1.2 g intravenously every six hours for five to seven days for severe adult leptospirosis, adjusting the plan to renal function and local specialist advice.Check immediate beta-lactam allergy, renal function and sodium or potassium formulation; observe for Jarisch–Herxheimer inflammation and do not mislabel it automatically as anaphylaxis.
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • Leptospirosis - GOV.UK
  • Leptospirosis (Weil's disease)
  • Human leptospirosis: guidance for diagnosis, surveillance and control
  • Rare and imported pathogens laboratory (RIPL)
  • Notifiable organisms and how to report them

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Renal pattern

Proteinuria, microscopic haematuria, pyuria, potassium disturbance and non-oliguric or oliguric acute kidney injury reflect tubulointerstitial injury.

Cardiac involvement

Myocarditis may present with chest discomfort, hypotension, conduction disturbance, atrial or ventricular arrhythmia and heart failure.

  • Provide oral hydration and paracetamol within safe limits, but avoid nephrotoxic self-medication when renal involvement remains possible.
  • Arrange early reassessment of symptoms, urine output, renal and liver function, with immediate return for jaundice, breathlessness, bleeding, reduced urine, confusion or persistent vomiting.