Infectious Diseases & Tropical Medicine & Internal Medicine & Family Medicine
Leptospirosis
Leptospirosis is a worldwide bacterial zoonosis caused by spirochetes of the Leptospira genus - principally Leptospira interrogans sensu lato - transmitted to humans through skin or mucous membrane contact with water or soil contaminated by the urine of infected reservoir animals (rats + rodents + cattle + pigs + dogs). It is the world's most widespread zoonosis, with an estimated annual incidence of 1.03 million severe cases and 58,900 deaths, according to WHO data (Abela-Ridder 2010). It occurs mainly in tropical and subtropical regions (Southeast Asia + Latin America + Oceania + sub-Saharan Africa), but is also present in temperate countries including Canada, particularly among at-risk workers (farmers + veterinarians + livestock breeders + sewage workers + military personnel) and travelers returning from endemic areas (adventurers + participants in cross-country forest races + after freshwater aquatic activities). In Canada, leptospirosis is relatively rare, but on the increase with travel to tropical zones - it should be suspected in any traveller returning from an endemic zone with an acute febrile syndrome. The clinical spectrum is highly variable: in 90 % of cases, the disease is benign and self-limiting (anicteric form - flu-like syndrome + aseptic meningitis); in 5-10 % of cases, it progresses to the severe form - Weil's syndrome - characterized by the classic triad: jaundice + acute renal failure + bleeding disorders, with a mortality of 5-40 % depending on access to care. Early antibiotic treatment (doxycycline or penicillin G) is essential to reduce the duration of the disease and prevent progression to the severe form.
Microbiology, epidemiology, and pathophysiology
- Pathogen, reservoirs, and modes of transmission Leptospira - taxonomy and microbiological characteristics: fine + helical + aerobic + motile spirochaetes (S- or C-shaped hooked ends) → too small to be seen under standard light microscope → darkfield microscopy + or fluorescence techniques → genus Leptospira: 2 main pathogenic species: L. interrogans sensu lato (over 300 serovars grouped into 24 serogroups) + L. borgpetersenii → non-pathogenic: L. biflexa (environmental saprophyte) → serovars are the epidemiological units → most frequent serovars: Icterohaemorrhagiae (rat + Weil syndrome) + Canicola (dog) + Pomona (cattle + pigs) + Grippotyphosa (wild rodents) + Hardjo (cattle) → animal reservoirs and sources of contamination: main reservoirs: rats + rodents (asymptomatic chronic reservoirs → persistent urinary excretors) + dogs + cattle + pigs + sheep + cats (less frequently) → reservoir animals excrete leptospires in their urine → contamination of freshwater + moist soil + mud → leptospires survive several weeks to several months in warm freshwater + moist soil → favorable conditions: stagnant water + flooding + heavy rain → neutral to slightly alkaline pH + temperature 20-30°C → transmission to humans : skin or mucous membrane contact with contaminated water or soil → leptospires penetrate through skin wounds (cuts + scratches + sores) → or intact mucous membranes (eyes + nose + mouth) → or macerated skin (prolonged bathing in contaminated water) → human-to-human transmission: exceptional (sexual contact + breast milk - very rare) → NO airborne transmission → occupational and recreational risk factors: farmers + livestock breeders + veterinarians + sewage workers + slaughterhouse workers + military personnel + firefighters + freshwater swimmers + canoeists + triathletes + hikers in wetlands + travelers in endemic areas (Southeast Asia + Amazon + Caribbean + Pacific) after floods + running in forests (e.g. Eco-Challenge + adventure raids)
- Pathophysiology and clinical phases of leptospirosis: phase I - leptospiremic (D1-J7 after exposure): cutaneous or mucosal penetration → invasion of the bloodstream → leptospiremia → dissemination to all organs (liver + kidneys + CNS + lungs + muscles + eyes) → bacteremia is intense in the first 7 days → blood cultures + positive urinocultures + serology often still negative → lesion mechanisms: leptospires release lipopolysaccharides (LPS) + lipoproteins + hemolysins + proteases → small-vessel vasculitis → endothelial lesions → increased vascular permeability → petechial hemorrhages + thrombocytopenia → the leptospirosis toxins + direct invasion of renal tubular cells → ARF + jaundice (hepatocyte involvement) → acute tubular necrosis → partial recovery of renal function often possible if treated early → phase II - immunological (J7-J14): spontaneous disappearance of leptospiremia (leptospires are eliminated from the blood by antibodies) → appearance of anti-Leptospira IgM → immune response → either resolution (mild form) → or paradoxical worsening (Weil syndrome) → leptospires persist in the kidneys → excreted in urine for up to 4-6 weeks + in the eyes (late uveitis) → phase III - (late - weeks to months later): chronic uveitis (main long-term complication) + meningoencephalitis → neurological sequelae → Jarisch-Herxheimer phase (possible): release of toxins after antibiotic therapy → transient worsening of symptoms in the first few hours of treatment (similar to syphilis and borreliosis)
Clinical presentation, diagnosis, and treatment
| Aspect / phase | Data, criteria and procedures | Key studies and recommendations |
|---|---|---|
| Clinical Presentation — Mild Form and Weil's Syndrome Anicteric form — sudden fever — myalgia — hemorrhagic conjunctivitis — Weil's syndrome — jaundice — ARF — hemorrhages — thrombocytopenia — ARDS — aseptic meningitis — late uveitis |
Clinical forms of leptospirosis according to severity: mild form - anicteric (90 % of cases): incubation: 2-30 days (average 10 days) → leptospiremic phase: abrupt onset → high fever (39-40°C) + chills + intense headache (frontal + retro-orbital) + intense myalgias (especially calves + lumbar + thighs - characteristic sign «calves very painful on bimanual pressure») + bilateral hemorrhagic conjunctivitis (conjunctival injection + subconjunctival hemorrhages - very suggestive of leptospiraemia) + bilateral hemorrhagic conjunctivitis (conjunctival injection + subconjunctival hemorrhages - very suggestive of leptospiraemia).conjunctival hemorrhages - very suggestive) → photophobia + arthritis + skin rash (5-10 % - ephemeral) + immunological phase : aseptic meningitis (50 % of cases) → headache + stiff neck → CSF: lymphocytic pleocytosis + normal or slightly elevated proteins + normal glucose → sometimes → meningoencephalitis + brownish urine + myocarditis + late uveitis + prognosis: spontaneous recovery in 2-3 weeks in the vast majority of mild forms → severe form - Weil syndrome (5-10 % of cases): classic Weil triad (1886): 1/ jaundice (cholestatic jaundice + hepatic cytolysis - intense jaundice → saffron coloration of skin + conjunctivae) + 2/ acute renal failure (oligoanuric ARF - acute tubular necrosis → very high urea + creatinine → hyperkalemia → possible dialysis) + 3/ bleeding disorders (severe thrombocytopenia 120 µmol/L) + severe thrombocytopenia | Levett 2001 — Clinical Microbiology Reviews: comprehensive review of leptospirosis → epidemiology + presentation + diagnosis + treatment → international reference + Bharti 2003 — Lancet Infectious Diseases: global leptospirosis → epidemiology + manifestations + Weil 1886: original description of Weil's syndrome + Abela-Ridder 2010 — WHO: global burden of leptospirosis → 1.03 million severe cases + 58,900 deaths/year + Brett-Major 2009 — Cochrane: antibiotic treatment of leptospirosis + evidence + PHAC (Public Health Agency of Canada): leptospirosis surveillance in Canada + INSPQ Quebec: zoonoses + leptospirosis + WHO 2003: Leptospirosis guidelines + diagnosis + treatment |
| Biological diagnosis — serology and microbiology MAT serology - microscopic agglutination test - IgM ELISA - blood/urine PCR - blood culture - EMJH medium - CBC thrombocytopenia - bilirubin - creatinine - CSF meningitis - serological window - early false negatives |
Diagnosis of leptospirosis - sequential approach according to phase: early phase (J1-J7) - serology often negative: PCR on blood: reference method in early phase → detects Leptospira DNA in blood → sensitivity 70-90 % in leptospiremic phase (J1-7) → available in specialized laboratories → Merien 1992 - Journal of Clinical Microbiology : validation of PCR for diagnosis → blood culture on EMJH (Ellinghausen-McCullough-Johnson-Harris) medium: specific but slow growth (2-6 weeks) → enriched medium → result too late for therapeutic decision → epidemiological value + PCR on urine: D7-14 + (leptospires excreted in urine from D7) → variable sensitivity + late phase (D7 and beyond) - positive serology: microagglutination test (MAT - Microscopic Agglutination Test): serological reference method → gold standard → principle: patient serum + live Leptospira cultures (16 serovars) → agglutination by dark-field microscopy → titer ≥1:400 = probable diagnosis + or 4-fold increase in titer between two samples taken 15 days apart = confirmation → available in reference laboratories → result in 24-48h → IgM ELISA test: rapid screening test → detects anti-Leptospira IgM (appearing from D5-J7) → more sensitive than MAT in the early acute phase → widely used in developing countries → possible false positives (other tropical febrile diseases) → suggestive non-specific biology: CBC : moderate leukocytosis (10-15 × 10⁹/L) → thrombocytopenia (very suggestive - 50-70 % of cases) + liver workup: moderately elevated AST + ALT + very elevated bilirubin if Weil syndrome + predominant conjugated bilirubin (cholestatic jaundice) → moderately elevated PAL + renal workup: elevated creatinine + urea → hyperkalemia → hyponatremia (SIADH possible) → very high CK (rhabdomyolysis) → procalcitonin: often elevated but not very specific + CSF if meningitis suspected: lymphocytic pleocytosis + normal proteins + normal glucose → compatible aseptic meningitis + lumbar puncture if meningeal syndrome → main differential diagnosis in a tropical travel context: malaria → systematic malaria PCR workup if traveling from an endemic zone → dengue + typhus (Rickettsia) + hantavirus + hepatitis A + B + bacterial sepsis → always ask for a malaria workup BEFORE concluding to leptospirosis if returning from a tropical zone. | Merien 1992 — Journal of Clinical Microbiology: PCR + leptospirosis + method validation + sensitivity + Levett 2001 — Clinical Microbiology Reviews: MAT diagnostic + ELISA IgM + PCR → reference algorithm + WHO 2003: Leptospirosis guidelines → diagnosis → MAT as gold standard + Pappas 2008 — International Journal of Infectious Diseases: review of leptospirosis diagnostic tests + sensitivity + specificity + ASPC + INSPQ Quebec: leptospirosis diagnosis in Canada → reference laboratories → National Microbiology Laboratory (NML — Winnipeg): MAT available for Canada + MSSS Quebec: mandatory reporting of leptospirosis |
| Antibiotic treatment, prevention, and chemoprophylaxis Doxycycline — penicillin G — ampicillin — cefotaxime — ceftriaxone — mild oral form — severe IV form — Jarisch-Herxheimer — doxycycline chemoprophylaxis — PPE prevention — drinking water — avoid swimming — mandatory declaration |
Antibiotic treatment of leptospirosis: principle: antibiotic therapy is effective if initiated early (within the first 7 days) → reduces duration of illness + complications → in late phase (after D7) → benefit less clearly demonstrated but recommended by all guidelines → Brett-Major 2009 - Cochrane: antibiotics + leptospirosis → reduced duration of symptoms + complications → moderate level of evidence → don't wait for diagnostic confirmation to treat if strong clinical suspicion; mild form - oral treatment: doxycycline 100 mg × 2/d × 7 days → reference treatment for mild forms → or ampicillin 500-750 mg × 4/d × 7 days → or amoxicillin 500 mg × 3/d × 7 days → or azithromycin 500 mg D1 then 250 mg/d × 4 days (if allergic to cyclins or penicillin) → doxycycline chemoprophylaxis (post-exposure prevention): doxycycline 200 mg/week → for workers exposed for a defined exposure period → or travellers to high-risk areas for a short period → Sehgal 2000 - Journal of Infectious Diseases (RCT): prophylactic doxycycline (200 mg/week) → 95 % reduction in risk of severe leptospirosis → robust data → BUT: effect limited to severe forms → does not prevent 100 % mild infections → prophylactic doxycycline not routinely recommended for all travelers → reserved for high-risk exposures (flooding + prolonged aquatic activities in endemic areas); severe form (Weil syndrome) - IV treatment: penicillin G 1.5 MIU IV × 6/d × 7 days → reference treatment for severe forms → or ampicillin 1 g IV × 4/d × 7 days → or cefotaxime 1 g IV × 4/d → or ceftriaxone 1 g IV × 1/d → Edwards 1988 - Annals of Internal Medicine (RCT): penicillin IV + severe leptospirosis → reduced duration of symptoms + positive effects on complications → Jarisch-Herxheimer reaction: possible in the first few hours of treatment (release of toxins during lysis of spirochetes) → chills + transient worsening of fever + hypotension → symptomatic treatment (antipyretics + filling) → usually lasts <24h → supportive care in severe forms: hemodialysis if severe ARF + mechanical ventilation if ARDS + platelet transfusion if severe bleeding + vascular filling + inotropes if cardiogenic shock → prevention: PPE (personal protective equipment): boots + waterproof gloves + overalls for exposed workers → avoid swimming in stagnant freshwater after rain or flooding → do not walk barefoot in flooded areas → protect skin wounds → animal vaccination (dogs) → human vaccination: vaccine available in some countries (Cuba + France) → not available in Canada → animal vaccination (cattle + pigs + dogs) reduces Leptospira excretion into the environment | Brett-Major 2009 — Cochrane : antibiotics + leptospirosis → reduced duration + complications → evidence + Sehgal 2000 — Journal of Infectious Diseases (RCT) : prophylactic doxycycline 200 mg/week → −95 % severe leptospirosis → reference for chemoprophylaxis + Edwards 1988 — Annals of Internal Medicine (RCT) : IV penicillin + severe leptospirosis → reduced complications → reference for IV treatment + Levett 2001 — Clinical Microbiology Reviews : treatment + prevention → comprehensive review + WHO 2003 : Leptospirosis guidelines → treatment + prevention + Berman 2020 — UpToDate : leptospirosis → treatment → update + ASPC + INSPQ Quebec : leptospirosis + mandatory declaration in Quebec (MSSS) + MSSS : notifiable disease (MADO) — deadline : 5 days → Health Canada : no approved vaccine for leptospirosis in Canada |
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For any traveler returning from a tropical zone with acute febrile syndrome plus calf myalgia, hemorrhagic conjunctivitis, and thrombocytopenia, leptospirosis should be suspected—and a malaria workup should be performed simultaneously: Do not wait for serological confirmation to start doxycycline if clinical suspicion is strong. Serology (MAT) is often negative in the first week—blood PCR allows for early diagnosis. In case of Weil's syndrome, hospitalize immediately and start IV penicillin G. Leptospirosis is a notifiable disease in Quebec (MSSS—5-day delay).
Situations requiring urgent hospitalization
Patient returning from a tropical zone (Asia + Caribbean + Amazon + Africa) with high fever + intense jaundice + very high creatinine + severe thrombocytopenia (<50 × 10⁹/L) + hemorrhages → Probable Weil's disease → Urgent hospitalization → Malaria screening as a priority + Leptospira PCR + MAT serology → Penicillin G 1.5 million IU IV x 6/day → Intensive care → Hemodialysis if AKI → Hemodynamic monitoring → Do not wait for confirmation to treat.
Patient with confirmed or suspected leptospirosis + respiratory distress + saturation <90 % + hemoptic cough + opacities on chest x-ray → ARDS due to alveolar hemorrhage → resuscitation emergency → call 911 → intubation and mechanical ventilation in intensive care unit → continuation of IV antibiotic therapy → very high mortality without aggressive management.
Worker (farmer + breeder + veterinarian + sewage worker) exposed to contaminated water during a flood + sudden fever + calf myalgia ++ + bilateral conjunctivitis → probable leptospirosis → urgent medical consultation → blood PCR + MAT serology → CBC + liver and renal function tests + CK → doxycycline 100 mg × 2/day × 7 days without waiting for confirmation if presumed mild form → MSSS declaration + regional medical inspector report.
Consult at Clinique Omicron
Clinique Omicron physicians evaluate febrile syndromes post-travel and in the context of occupational exposure, prescribe the appropriate diagnostic workup (Leptospira PCR + serological MAT + malaria screening + CBC + liver and kidney function tests), initiate oral doxycycline upon clinical suspicion of mild forms, refer urgently for hospitalization for severe forms, and ensure mandatory reporting to the MSSS. Consultations are available at several service points in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not replace the advice of a doctor or an infectious disease specialist. Leptospirosis is a notifiable disease in Quebec. Any case of Weil's disease (jaundice + ARF + hemorrhage) is a medical emergency requiring immediate hospitalization.
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