Leptospirosis

Quick Answer

One-liner: Leptospirosis is a zoonotic spirochetal infection acquired through contact with contaminated water or animal urine that can progress from flu-like illness to life-threatening multi-organ failure with jaundice, renal failure, and pulmonary hemorrhage.

Leptospirosis is endemic in tropical and subtropical regions, particularly northern Australia (Queensland, Northern Territory). It ranges from mild self-limiting febrile illness (90%) to severe Weil's disease (icteric leptospirosis with jaundice, renal failure, hemorrhage) with 5-15% mortality, or devastating pulmonary hemorrhage syndrome (LPHS) with 30-70% mortality. Early empirical antibiotic therapy with ceftriaxone 2g IV daily or benzylpenicillin 1.2-1.5g IV q6h is critical, as diagnostic confirmation can take days to weeks.

---

ACEM Exam Focus

Primary Exam Relevance

• Microbiology: Leptospira interrogans spirochete; transmission cycle; animal reservoirs (rats, cattle, pigs); survival in freshwater
• Pathology: Systemic vasculitis mechanism; capillary leak; acute tubular necrosis; hepatocellular dysfunction without necrosis; immune-mediated pulmonary capillaritis
• Pharmacology: Penicillin G vs ceftriaxone efficacy; doxycycline prophylaxis mechanism; Jarisch-Herxheimer reaction risk

Fellowship Exam Relevance

• Written: High-yield tropical infectious disease; differential diagnosis of jaundice + AKI; recognition of conjunctival suffusion; Australian epidemiology (northern regions, occupational risks); differentiation from dengue, melioidosis, rickettsial disease
• OSCE: History-taking for occupational/recreational exposure; systematic examination for conjunctival suffusion; communication regarding prognosis in severe disease; retrieval decision-making in remote settings
• Key domains tested: Medical Expert (diagnostic reasoning, empirical treatment), Communicator (risk discussion, disposition planning), Health Advocate (occupational health, Indigenous health disparities)

---

Key Points

---

Epidemiology

Australian/NZ Specific

• Hotspots: Far North Queensland (Cairns, Townsville region), Northern Territory (Darwin, Katherine), northern New South Wales; cases spike post-cyclones and monsoonal flooding [2,9]
• Occupational risks: Banana and sugarcane farming, cattle/pig handling, feral pig hunting, sewage/sanitation workers, veterinarians, abattoir workers [10]
• Recreational risks: Freshwater swimming (creeks, billabongs), white-water rafting, canyoning, mud runs after heavy rainfall [11]
• Common serovars in Australia: L. interrogans serovars Zanoni, Australis (northern Australia); Hardjo (cattle-associated) [2]
• Indigenous populations: Aboriginal and Torres Strait Islander peoples have higher incidence due to occupational exposures (pastoral work, hunting), remote living conditions, and delayed healthcare access [12]
• New Zealand: Rare but reported in farm workers; dairy farming-associated exposures; Māori communities disproportionately affected due to agricultural occupations [13]

---

Pathophysiology

Mechanism

Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira (greater than 300 serovars, 10 pathogenic species) [14].

Transmission:

• Bacteria shed in urine of reservoir animals (rats, cattle, pigs, dogs) survive in warm, moist environments (freshwater, soil, mud) for weeks to months [15]
• Human infection occurs via direct contact with infected animal urine OR indirect contact with contaminated water/soil through mucous membranes (eyes, nose, mouth) or non-intact skin (abrasions, cuts) [16]

Infection Cycle:

Skin/mucosal entry → Bloodstream invasion (leptospiremia) → Systemic dissemination (all organs) → Immune phase (antibody production, organ damage)

Pathological Progression

Phase 1: Leptospiremic (Septicemic) Phase (Days 0-10)

• Spirochetes enter bloodstream within hours, replicate rapidly
• Systemic spread to all organs: liver, kidneys, lungs, CNS, eyes, muscles
• Clinical features: High fever (39-40°C), severe myalgia (especially calves - "leptospirosis calf pain"), headache, conjunctival suffusion
• Leptospires detectable in blood/CSF (PCR positive) [17]

Phase 2: Immune Phase (Days 10+)

• IgM antibodies develop, clear leptospires from blood (bacteremia ends)
• Paradoxical organ damage increases due to immune-mediated vasculitis
• Systemic capillary leak, endothelial damage → multi-organ dysfunction [18]

Organ-Specific Pathology:

Why It Matters Clinically

• Conjunctival suffusion (vasculitis of bulbar conjunctiva) appears early (days 3-5) and is highly specific - absent in dengue, influenza, malaria [26]
• Jaundice + modest transaminitis distinguishes from viral hepatitis (where ALT/AST >greater than 1000 U/L)
• Non-oliguric hypokalemic AKI is characteristic (proximal tubule dysfunction) vs typical oliguric hyperkalemic ATN in sepsis [27]
• Pulmonary hemorrhage can occur explosively (24-48h progression) - hemoptysis is a terminal event requiring immediate ICU/ECMO [28]

---

Clinical Approach

Recognition

Suspect leptospirosis in ANY patient with:

• Fever + myalgia (especially calf pain) + headache + conjunctival suffusion
• Exposure history: Freshwater contact (swimming, wading, occupational) within 2-30 days (incubation period typically 7-14 days, range 2-30 days) [29]
• High-risk occupation: Farming, livestock handling, veterinary work, sewage work, abattoir, feral pig hunting
• Geographic risk: Northern Australia (Queensland, NT), post-flooding/heavy rainfall
• Seasonal risk: Late summer/autumn (post-monsoonal in tropics)

Red flags for severe disease:

• Conjunctival suffusion + jaundice
• Thrombocytopenia (below 100,000/μL) + AKI (Cr greater than 1.5 mg/dL)
• Hemoptysis or dyspnea (pulmonary hemorrhage)
• Oliguria (below 400 mL/day)
• Altered mental status (CNS involvement)

Initial Assessment

Primary Survey (if severe/critical)

• A: Patent; risk of airway hemorrhage if pulmonary bleeding
• B: Assess for hemoptysis, crackles (pulmonary edema/hemorrhage), hypoxia (SpO₂ below 90%); LPHS can cause ARDS within hours
• C: Tachycardia, hypotension (septic shock vs bleeding); capillary refill; assess for hemorrhage (GI bleeding, petechiae, epistaxis)
• D: GCS (meningitis vs uremic encephalopathy); pupils (uveitis rare in acute phase)
• E: Jaundice (scleral icterus), petechiae, muscle tenderness (calves), temperature (typically 39-40°C)

History

Key Questions

Red Flag Symptoms

Examination

General Inspection

• Fever: Typically high (39-40°C), abrupt onset
• Posture: Reluctance to move due to severe myalgia
• Color: Jaundice (icteric sclera, skin) - indicates Weil's disease
• Respiratory distress: Tachypnea, hypoxia - assess for LPHS/ARDS

Specific Findings

• cannot walk; CK elevated | | Neurological | Neck stiffness (meningismus); altered GCS | Aseptic meningitis (10-15% of cases) [23] |

---

Investigations

Immediate (Resus Bay)

Standard ED Workup

Advanced/Specialist

Point-of-Care Ultrasound

• POCUS indications:
  • "Lung POCUS: B-lines (pulmonary edema), pleural effusions (bilateral in Weil's disease)"
  • "Cardiac: Assess for global hypokinesis (myocarditis rare but reported); volume status (IVC collapsibility)"
  • "Renal: Echogenicity (ATN); exclude obstruction"

Diagnostic Challenges in Remote/Rural Settings:

• PCR requires 24-72h turnaround (samples sent to Brisbane/Darwin/Sydney pathology)
• MAT is NOT useful for acute management (requires paired sera 10-14 days apart)
• Clinical diagnosis is mandatory - treat empirically based on history + examination (conjunctival suffusion, occupational exposure, jaundice)

---

Management

Immediate Management (First 10 minutes)

1. Airway: Assess patency; if hemoptysis → consider early intubation (consult ICU)
2. Breathing: High-flow oxygen if SpO₂ below 90%; ABG to assess PaO₂; CXR (portable if unstable)
3. Circulation: 2× large-bore IV access; bloods (FBC, UEC, LFT, coags, cultures, glucose); IV fluid resuscitation (20 mL/kg crystalloid if hypotensive; CAUTION if pulmonary edema/LPHS)
4. Disability: GCS; glucose; pupils
5. Exposure: Temperature; assess for jaundice, petechiae, calf tenderness
6. START ANTIBIOTICS IMMEDIATELY if clinically suspected (do NOT wait for PCR/serology)
   - Severe/admitted: Ceftriaxone 2g IV OR Benzylpenicillin 1.2-1.5g IV q6h
   - Mild/outpatient: Doxycycline 100mg PO BD

Resuscitation (if severe/Weil's disease/LPHS)

Airway

• Early intubation if hemoptysis (protect airway from blood aspiration)
• RSI with standard agents; avoid ketamine if severe hypertension (though rare)

Breathing

• Oxygen therapy: Target SpO₂ 92-96%; high-flow nasal cannula (HFNC) if hypoxic
• Mechanical ventilation (if LPHS/ARDS):
  • "Lung-protective ventilation: Tidal volume 6 mL/kg IBW, plateau pressure below 30 cmH₂O"
  • PEEP optimization (recruit alveoli, tamponade bleeding)
  • Consider ECMO early if refractory hypoxia (PaO₂/FiO₂ below 100) - LPHS mortality 30-70%, ECMO can be life-saving [37]

Circulation

• Fluid resuscitation: 20-30 mL/kg crystalloid (0.9% saline or Hartmann's) if hypotensive
  • "CAUTION: Pulmonary capillary leak in LPHS → risk of flash pulmonary edema with aggressive fluids; titrate to clinical response (MAP greater than 65 mmHg, urine output greater than 0.5 mL/kg/h)"
• Vasopressors if fluid-refractory shock: Noradrenaline 0.05-0.5 μg/kg/min (first-line)
• Blood products if hemorrhage:
  • Packed red cells (target Hb greater than 70 g/L; greater than 90 g/L if ongoing bleeding)
  • Platelets if below 50,000/μL AND active bleeding (or below 10,000/μL prophylactic)
  • FFP if INR greater than 2.0 AND bleeding
  • Tranexamic acid (TXA) controversial in LPHS (no RCT data; some centers use 1g IV loading dose)

Medications

Duration: 7 days (IV or PO); switch from IV to PO (doxycycline 100mg BD) once afebrile 24-48h and clinically improving

Jarisch-Herxheimer Reaction:

• Rare in leptospirosis (more common in syphilis, relapsing fever)
• Transient fever, hypotension, tachycardia within 2-4 hours of first antibiotic dose (endotoxin release from dying spirochetes)
• Management: Supportive (IV fluids, paracetamol); do NOT withhold antibiotics
• Monitor BP closely for first 4h after initial dose (especially in severe disease)

Paediatric Dosing

Ongoing Management

Renal Support:

• Indications for dialysis: Severe AKI (Cr greater than 500 μmol/L, greater than 5.6 mg/dL), oliguria (below 400 mL/24h), hyperkalemia (K⁺ greater than 6.5 mmol/L), metabolic acidosis (pH below 7.2), uremic symptoms (pericarditis, encephalopathy), pulmonary edema refractory to diuretics
• Modality: Intermittent hemodialysis (IHD) OR continuous renal replacement therapy (CRRT) if hemodynamically unstable
• Prognosis: Renal recovery is excellent in survivors (90-95% regain normal function within 3-6 months) [39]

Pulmonary Support:

• LPHS management: ICU admission, mechanical ventilation (lung-protective strategy), PEEP 10-15 cmH₂O, consider prone positioning
• ECMO: Consider early referral to ECMO center (Royal Prince Alfred [Sydney], Alfred Hospital [Melbourne], Prince Charles [Brisbane]) if PaO₂/FiO₂ below 100 despite optimal ventilation [40]

Corticosteroids:

• Controversial - no high-quality RCT evidence
• Some observational studies suggest methylprednisolone 1g IV daily × 3 days may reduce mortality in LPHS if given within 24h of symptom onset [41]
• NOT routinely recommended; discuss with ICU/infectious diseases

Monitoring:

• Daily FBC (thrombocytopenia trend), UEC (AKI progression), LFT
• Fluid balance (strict input/output; risk of pulmonary edema)
• ABG if respiratory involvement
• ECG if QT prolongation (electrolyte disturbances)

Definitive Care

• ICU admission: Weil's disease (jaundice + AKI), LPHS, septic shock, respiratory failure, renal replacement therapy
• Infectious diseases consult: Severe cases, diagnostic uncertainty (malaria, dengue, melioidosis co-infection possible)
• Nephrology consult: AKI requiring dialysis
• Respiratory/ICU consult: LPHS, ECMO consideration

---

Disposition

Admission Criteria

• ICU/HDU:

  • Weil's disease (jaundice + AKI + hemorrhage)
  • Pulmonary hemorrhage syndrome (LPHS)
  • Septic shock (hypotension despite fluids)
  • Respiratory failure (PaO₂ below 60 mmHg, SpO₂ below 90% on O₂)
  • AKI requiring dialysis
  • Thrombocytopenia below 50,000/μL with bleeding
  • Altered mental status (meningitis, encephalopathy)

• General ward:

  • "Moderate disease: Fever, myalgia, unable to tolerate oral intake, dehydration"
  • Thrombocytopenia 50-100,000/μL (monitor for progression)
  • AKI (Cr 150-300 μmol/L) without oliguria
  • "Social factors: Remote location, inability to return if deteriorates, Indigenous communities with limited healthcare access"

ICU/HDU Criteria

• Septic shock (MAP below 65 mmHg despite 30 mL/kg fluid)
• Respiratory failure (need for mechanical ventilation)
• LPHS (any hemoptysis → ICU activation)
• AKI requiring RRT
• GCS below 13 (meningitis, encephalopathy)
• Thrombocytopenia below 20,000/μL or below 50,000/μL with active bleeding

Discharge Criteria

• Mild disease (afebrile, able to tolerate oral fluids/food, normal renal/liver function, platelets greater than 100,000/μL, no respiratory symptoms)
• Reliable follow-up: GP review within 48h; pathology review (ensure PCR sent; arrange convalescent serology in 10-14 days if acute serology negative)
• Ability to return: Lives within 1h of hospital; has transport; understands red flags

Red flags to return immediately:

• Jaundice (yellowing of eyes/skin)
• Hemoptysis (coughing blood)
• Severe shortness of breath
• Reduced urine output (below 500 mL/day)
• Confusion or drowsiness
• Persistent vomiting (unable to keep down antibiotics)

Follow-up

• GP review: 48h (ensure improving; review pathology results)
• Specialist review: Infectious diseases at 2 weeks (if severe disease); nephrology if AKI (assess renal recovery at 3-6 months)
• Ophthalmology referral: 4-6 weeks if uveitis symptoms (eye pain, photophobia, blurred vision) - late complication in 10% of cases [24]
• Convalescent serology: 10-14 days post-symptom onset (MAT or IgM ELISA) to confirm diagnosis if acute serology negative
• Work clearance: Minimum 7 days off work; longer if severe disease; return to work once afebrile 48h and strength recovered

GP letter requirements:

• Diagnosis (confirmed/suspected leptospirosis)
• Severity (mild/moderate/severe; Weil's disease vs uncomplicated)
• Treatment (antibiotic, duration, completion date)
• Complications (AKI, LPHS, etc.)
• Follow-up plan (convalescent serology, specialist referrals)
• Work clearance advice
• Public health notification (leptospirosis is notifiable in all Australian states/territories)

---

Special Populations

Paediatric Considerations

• Less common in children (school-age children: farm exposure, swimming)
• Clinical features similar to adults; conjunctival suffusion may be more subtle
• Dosing: Weight-based (see Medications section)
• Avoid doxycycline below 8 years (dental staining) → use azithromycin 10 mg/kg daily × 5 days
• Lower threshold for admission (young children dehydrate rapidly)

Pregnancy

• High risk: Leptospirosis in pregnancy associated with miscarriage, preterm labor, stillbirth, vertical transmission [42]
• Antibiotic choice: Benzylpenicillin or ceftriaxone (both safe in pregnancy); AVOID doxycycline (teratogenic - dental/bone abnormalities)
• Azithromycin 500mg PO daily × 5 days if mild disease (safe in pregnancy)
• Obstetric consult: All pregnant patients with leptospirosis (even mild) require O\u0026G review (fetal monitoring, assess for preterm labor)
• Admission threshold lower: Monitor fetal wellbeing; CTG if greater than 24 weeks

Elderly

• Higher mortality (reduced physiological reserve)
• More likely to develop severe AKI, cardiac complications
• Polypharmacy: Check drug interactions (e.g., warfarin + antibiotics)
• Lower threshold for admission (limited functional reserve)

Indigenous Health

Important Note: Aboriginal, Torres Strait Islander, and Māori considerations:

• Higher incidence: Aboriginal and Torres Strait Islander peoples in northern Australia have disproportionately higher rates due to occupational exposures (pastoral work, cattle stations), recreational activities (hunting, fishing), and living conditions (remote communities, limited access to clean water) [12]
• Delayed presentation: Geographic isolation, limited transport, cultural distrust of healthcare systems → present later with severe disease
• Cultural safety: Engage Aboriginal Health Workers/Liaison Officers early; involve family in decision-making; respect cultural protocols (e.g., gender-specific care preferences)
• Communication: Use plain language; interpreter services (Aboriginal English ≠ Standard Australian English); visual aids
• Disposition challenges: Remote communities may lack dialysis facilities → retrieval to tertiary center (Darwin, Cairns, Townsville) may separate patient from family/country
• Prevention: Community health education (avoid stagnant water post-floods, wear protective boots when farming/hunting); occupational health programs on cattle stations
• Māori (New Zealand): Dairy farming, agricultural work common; involve whānau (extended family) in care decisions; cultural liaison services available in NZ EDs

---

Pitfalls \u0026 Pearls

---

Viva Practice

---

OSCE Scenarios

Station 1: Focused History - Leptospirosis

Format: History Taking Time: 11 minutes Setting: ED cubicle

Candidate Instructions:

You are the ED registrar. A 45-year-old man presents with 3 days of fever, headache, and muscle pain. Take a focused history to determine the cause of his symptoms and assess for serious complications.

Examiner Instructions: The patient is a banana farmer from North Queensland with suspected leptospirosis. Candidates should systematically elicit risk factors (occupational, recreational exposures), assess severity (red flags for Weil's disease, LPHS), and demonstrate understanding of differential diagnosis (dengue, melioidosis, influenza).

Actor/Patient Brief:

• 45-year-old man, banana farmer from Tully (Far North Queensland)
• 3 days of high fever (39-40°C), severe headache, bilateral calf pain ("worst pain ever, can't walk properly")
• 10 days ago: Heavy rainfall, worked in flooded banana plantation (wading through muddy water up to knees, wearing boots but feet soaked)
• No travel outside FNQ recently
• No cough, shortness of breath, or chest pain
• Urine output seems normal
• No yellowing of eyes/skin (no jaundice)
• Eyes feel "a bit red and irritated" for 1 day (no discharge)
• Otherwise healthy, no chronic medical conditions, no medications
• If asked: Drinks rain water from tank at home (no town water supply)
• If asked: Rats seen around banana sheds regularly

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Elicits occupational exposure (farming) and freshwater contact (flooded fields) - critical for diagnosis
  • Asks about red eyes (conjunctival suffusion) - pathognomonic sign
  • Screens for red flags (jaundice, hemoptysis, oliguria) - identifies severe disease
  • Considers appropriate differentials (dengue, melioidosis in FNQ endemic area)

---

Station 2: Communication - Breaking Bad News (Leptospirosis LPHS)

Format: Communication Time: 11 minutes Setting: Relatives' room

Candidate Instructions:

You are the ED registrar. A 38-year-old man was brought in 2 hours ago with fever and hemoptysis. He is now intubated in the ICU with suspected leptospirosis pulmonary hemorrhage syndrome (LPHS). His wife has just arrived. Speak to her about his condition, the diagnosis, and the prognosis. You do NOT need to take a history.

Examiner Instructions: The patient has LPHS with ARDS, intubated, PaO₂/FiO₂ 90 (severe ARDS), on high PEEP, requiring vasopressors. Mortality for LPHS is 30-70%. ECMO retrieval to Royal Prince Alfred Hospital (Sydney) is being arranged. Candidate should demonstrate empathetic communication, clear explanation of serious illness, realistic but not hopeless prognosis, and involve family in decision-making.

Actor/Patient Brief (Wife):

• Distressed, crying, "What's happening? I thought he just had the flu?"
• Husband is a sewage worker, healthy otherwise, 2 young children (ages 5 and 8)
• Started with fever/headache 3 days ago, seemed like flu, then this morning coughed up blood → called ambulance
• If asked: He mentioned his eyes were red and his legs hurt
• If asked: Yes, he works in sewage treatment plant (contact with rat-contaminated water)
• If candidate explains well, responds: "Will he survive? What are his chances?"
• If candidate avoids giving prognosis, pushes: "Please, I need to know the truth - is he going to die?"

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Honest prognosis (doesn't give false reassurance but also doesn't say "he's going to die")
  • Explains LPHS in lay terms (lung bleeding, not "alveolar capillaritis")
  • Empathetic, allows wife to express emotion
  • Offers support (social work, chaplaincy, ICU visiting)

---

Station 3: Examination - Systematic Assessment for Leptospirosis

Format: Clinical Examination Time: 11 minutes Setting: ED examination bay

Candidate Instructions:

You are the ED registrar. A 30-year-old woman presents with 4 days of fever and muscle pain. She is a veterinarian. Perform a focused examination to identify clinical signs that will help you make a diagnosis. You may ask the examiner for specific findings.

Examiner Instructions: This is a simulated case of leptospirosis. Candidates should demonstrate a systematic approach focusing on eyes (conjunctival suffusion), skin (jaundice, petechiae), abdomen (hepatomegaly), musculoskeletal (calf tenderness), and vital signs. Award marks for systematic technique and identification of key signs.

Findings (Examiner provides when candidate examines each system):

• General inspection: Patient appears uncomfortable, flushed, sweating
• Vital signs: HR 105 bpm, BP 120/75 mmHg, RR 18/min, SpO₂ 98% on air, temp 39.2°C
• Eyes: Bilateral conjunctival suffusion (non-purulent redness of bulbar conjunctiva); no discharge; PERRL
• Skin: No jaundice; no petechiae or rash; skin warm to touch
• Cardiovascular: Tachycardic, normal heart sounds, no murmurs, cap refill below 2 sec
• Respiratory: Clear breath sounds bilaterally, no crackles or wheeze
• Abdomen: Soft, mild RUQ tenderness (liver edge palpable 1 cm below costal margin, smooth, tender); no splenomegaly; bowel sounds present
• Musculoskeletal: Severe bilateral calf tenderness (patient winces when calves palpated); no swelling or erythema; full range of motion
• Neurological: GCS 15, alert and oriented; neck supple (no meningismus); no focal neurology

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Actively examines eyes for conjunctival suffusion (many candidates forget this - it's pathognomonic)
  • Palpates calves (classic "leptospirosis calf pain")
  • Systematic approach (not haphazard jumping between systems)
  • Correctly interprets findings and states leptospirosis as top differential

---

SAQ Practice

Question 1 (6 marks)

Stem: A 40-year-old pig farmer presents to your rural ED with 5 days of fever, jaundice, and reduced urine output. You suspect Weil's disease (severe leptospirosis).

Question: List SIX immediate management priorities in the Emergency Department for this patient.

Model Answer:

1. Airway assessment - ensure patent airway; assess for hemoptysis (risk of pulmonary hemorrhage) (1 mark)
2. Oxygen therapy - administer high-flow oxygen if SpO₂ below 90%; obtain ABG to assess oxygenation and acid-base status (1 mark)
3. IV access and fluid resuscitation - 2× large-bore IV cannulae; IV crystalloid 20-30 mL/kg (0.9% saline or Hartmann's) if hypotensive; cautious fluid balance (risk of pulmonary edema) (1 mark)
4. Empirical antibiotics - Ceftriaxone 2g IV STAT (or benzylpenicillin 1.5g IV q6h); do NOT wait for serology confirmation (1 mark)
5. Blood investigations - FBC (thrombocytopenia?), UEC (AKI severity), LFT (bilirubin, transaminases), coagulation studies (DIC?), blood cultures, leptospira PCR, ABG (acidosis?) (1 mark)
6. ICU/HDU referral - Weil's disease requires critical care monitoring; likely to need renal replacement therapy (dialysis); nephrology consult (1 mark)

Examiner Notes:

• Accept: "Start antibiotics immediately" without specifying ceftriaxone (1 mark); give full mark if correct drug/dose specified
• Accept: "Bloods including FBC, UEC, LFT" (1 mark); listing each test separately does NOT gain extra marks
• Do not accept: "Take a full history" (not an immediate priority in critically unwell patient)
• Do not accept: "Wait for serology before starting antibiotics" (incorrect - empirical treatment is mandatory)

---

Question 2 (8 marks)

Stem: A 35-year-old banana farmer from Cairns presents with fever, severe calf pain, and red eyes. You suspect leptospirosis.

Question: Describe FOUR clinical features that would help you differentiate leptospirosis from dengue fever. (8 marks total - 2 marks per feature)

Model Answer:

1. Conjunctival suffusion - Present in 30-50% of leptospirosis (non-purulent bulbar conjunctival redness); RARE in dengue fever (conjunctivitis may occur but with discharge) (2 marks)

2. Severe bilateral calf myalgia - Classic in leptospirosis ("so severe patient cannot walk"); dengue causes myalgia but not specifically localized to calves (typically diffuse body aches, "breakbone fever") (2 marks)

3. Jaundice - Can occur in leptospirosis (Weil's disease - conjugated hyperbilirubinemia); RARE in dengue (only in severe dengue with hepatic failure, which is uncommon) (2 marks)

4. Acute kidney injury - Common in leptospirosis (40-50% of severe cases, often non-oliguric hypokalemic AKI); RARE in dengue (only in severe dengue with shock) (2 marks)

Examiner Notes:

• Accept alternative correct differentiators:
  • Occupational exposure history (farming, sewage work - leptospirosis; urban setting, Aedes mosquito - dengue) - 2 marks
  • Thrombocytopenia pattern (moderate in leptospirosis 50-100,000/μL; severe in dengue below 20,000/μL with plasma leakage)
  • Rash (absent in leptospirosis; petechial/maculopapular rash common in dengue)
• Do not accept vague answers like "different symptoms" without specifics

---

Question 3 (6 marks)

Stem: You are working in a remote Northern Territory clinic. A 28-year-old Aboriginal man who works on a cattle station presents with fever, headache, and muscle pain. He went swimming in a billabong 1 week ago. You suspect leptospirosis.

Question: List SIX important factors you would consider when deciding whether to request RFDS retrieval to a tertiary hospital for this patient.

Model Answer:

1. Presence of red flags - Conjunctival suffusion + jaundice (Weil's disease); hemoptysis (LPHS); oliguria/anuria (severe AKI) - any of these mandates retrieval (1 mark)

2. Blood results if available - Thrombocytopenia + elevated creatinine (predictor of rapid deterioration even if currently stable) (1 mark)

3. Respiratory status - SpO₂, respiratory rate, any dyspnea or chest symptoms (pulmonary hemorrhage has 30-70% mortality, requires ICU/ECMO) (1 mark)

4. Local monitoring capability - Can the remote clinic provide 4-hourly vital sign monitoring, daily bloods, urine output measurement? If not, lower threshold for retrieval (1 mark)

5. Geographic isolation - How far is patient's home from clinic? Does he have transport to return if deteriorates? Remote cattle station location may necessitate retrieval even if currently stable (1 mark)

6. Social/cultural factors - Family support, cultural preference (involve Aboriginal Health Worker in discussion), ability to return for follow-up, patient preference regarding retrieval vs staying in community (1 mark)

Examiner Notes:

• Accept: "Vital signs" / "hemodynamic stability" (1 mark)
• Accept: "Availability of dialysis" / "need for renal replacement therapy" (1 mark)
• Accept: "Discuss with RFDS retrieval consultant" (1 mark if framed as part of decision-making process)
• Do not accept: Generic "severity of disease" without specifics

---

Question 4 (8 marks)

Stem: A 50-year-old sewage worker is diagnosed with leptospirosis. He asks about prevention for his coworkers who continue to work in the same environment.

Question: Outline FOUR prevention strategies to reduce the risk of leptospirosis in occupational settings. (8 marks total - 2 marks per strategy)

Model Answer:

1. Personal protective equipment (PPE) - Waterproof gloves, boots, and overalls when working in contaminated water or sewage; eye protection (goggles) to prevent splash exposure to mucous membranes; change out of wet clothes promptly (2 marks)

2. Doxycycline prophylaxis - 200 mg orally once weekly for workers with continuous high-risk exposure (sewage workers, abattoir workers, farmers in endemic areas); 95% effective in preventing symptomatic disease; side effects include photosensitivity and GI upset (2 marks)

3. Rodent control - Implement pest control programs to reduce rat populations (rats are main reservoir for Leptospira serovar Icterohaemorrhagiae); secure food storage; eliminate rat harbourage (rubbish piles, dense vegetation near work areas) (2 marks)

4. Wound care and hygiene - Cover all cuts and abrasions with waterproof dressings before work (leptospires enter through broken skin); wash hands and exposed skin thoroughly with soap after work; shower immediately after exposure to contaminated water (2 marks)

Examiner Notes:

• Accept alternative correct strategies:
  • Vaccination (livestock vaccination to reduce animal reservoir; human vaccine available in some countries but not Australia - 2 marks)
  • Environmental management (drain stagnant water, fence off contaminated water sources, provide clean piped water - 2 marks)
  • Worker education (train workers on risks, symptoms to recognize, when to seek medical care - 2 marks)
• Do not accept: "Avoid work" (not practical for occupational settings)
• 1 mark for strategy name, 1 mark for specific detail/rationale

---

Australian Guidelines

ARC/ANZCOR

• Not applicable - Leptospirosis is not a resuscitation/cardiac arrest condition covered by ARC/ANZCOR guidelines

Therapeutic Guidelines

• Therapeutic Guidelines: Antibiotic (eTG) [43]:
  • "Mild leptospirosis (outpatient): Doxycycline 100 mg PO BD for 7 days"
  • "Severe leptospirosis (inpatient): Ceftriaxone 2 g IV daily OR benzylpenicillin 1.2-1.5 g IV every 6 hours for 7 days"
  • "Pregnancy: Benzylpenicillin or ceftriaxone (avoid doxycycline); azithromycin 500 mg PO daily for 5 days if mild disease"

State-Specific

• Queensland Health Clinical Guidelines [44]:

  • Leptospirosis is a notifiable disease in Queensland (mandatory reporting to public health within 5 days of diagnosis)
  • "High-risk areas: Far North Queensland (Cairns, Townsville, Innisfail), particularly post-flooding"
  • "Occupational health guidelines for banana/sugarcane farmers: PPE (waterproof boots, gloves), doxycycline prophylaxis 200 mg weekly during high-risk periods (wet season)"
  • "Pathology: Leptospira PCR available at Queensland Health Forensic and Scientific Services (Brisbane); turnaround 24-72h"

• Northern Territory Department of Health [45]:

  • Leptospirosis notifiable disease (mandatory reporting within 24h for suspected cases)
  • Endemic in Top End (Darwin, Katherine, Arnhem Land)
  • "Aboriginal communities: Higher incidence due to occupational (pastoral work, hunting) and environmental exposures (billabongs, flooding)"
  • "Retrieval: NT Medical Retrieval Service (CareFlight) for transfers to Royal Darwin Hospital ICU"

• New South Wales Health [46]:

  • Notifiable disease (5-day reporting)
  • "Endemic areas: Northern Rivers region (Byron Bay, Lismore, Ballina), north coast"
  • "Public health response: Investigate clusters, occupational health follow-up (farm/abattoir workers)"

---

Remote/Rural Considerations

Pre-Hospital

• Ambulance/paramedic considerations:
  • High index of suspicion in endemic areas (northern Australia) during wet season
  • IV access, crystalloid resuscitation if hypotensive
  • Assess for hemoptysis (LPHS) - requires rapid transfer to hospital with ICU capability
  • Monitor for Jarisch-Herxheimer reaction if antibiotics given pre-hospital (rare but can cause transient hypotension)

Resource-Limited Setting

Modified approach when tertiary care unavailable:

• Diagnosis: Clinical diagnosis based on history (exposure) + examination (conjunctival suffusion, calf pain, jaundice) - do NOT wait for serology
• Treatment: Start IV ceftriaxone immediately (if unavailable, use benzylpenicillin or even oral doxycycline in mild cases)
• Monitoring: 4-hourly vital signs, daily urine output measurement (catheter if oliguria), daily visual assessment for jaundice
• Pathology: Send bloods (FBC, UEC, LFT) to regional lab if available; if not available, treat empirically and arrange retrieval
• Low threshold for retrieval: Any red flags (jaundice, hemoptysis, oliguria, thrombocytopenia + AKI) → activate RFDS

Retrieval

Criteria for RFDS retrieval (contact RFDS 1300 367 330 or state-specific number):

• Absolute indications:

  • Weil's disease (jaundice + AKI + hemorrhage)
  • Pulmonary hemorrhage syndrome (hemoptysis, hypoxia, ARDS)
  • Septic shock (hypotension despite fluids)
  • AKI requiring dialysis (Cr greater than 500 μmol/L, oliguria, hyperkalemia greater than 6.5 mmol/L)
  • Respiratory failure (SpO₂ below 90% on oxygen)
  • Altered mental status (GCS below 13)

• Relative indications:

  • Thrombocytopenia + AKI (even if stable - predictor of deterioration)
  • Moderate AKI (Cr 200-500 μmol/L) in resource-limited setting
  • Geographic isolation (unable to return if deteriorates)
  • Social factors (Indigenous patient, limited family support, cultural preference for tertiary center care)

RFDS retrieval process:

1. Contact RFDS retrieval service (NT: 08 8920 9000 Darwin; QLD: 1300 367 330; NSW: 1800 625 800)
2. Provide clinical handover to RFDS doctor (patient details, suspected diagnosis, vital signs, bloods, treatment given)
3. Continue IV antibiotics during flight (ceftriaxone preferred - once daily dosing)
4. Monitor for Jarisch-Herxheimer reaction (first 2-4h after antibiotics)
5. Destination: Tertiary center with ICU and dialysis (Royal Darwin Hospital, Cairns Hospital, Townsville Hospital, Royal Brisbane and Women's Hospital)
6. Consider family transport (RFDS can arrange family member to travel with patient if culturally appropriate)

RFDS considerations:

• Blood products: Most RFDS aircraft carry O-negative packed red cells, platelets may not be available (request in advance if severe bleeding)
• Dialysis: NOT available during RFDS flight (cannot perform in-flight dialysis - patient must be stabilized for duration of flight or deterioration managed medically)
• Airstrip access: Flooding (same conditions that cause leptospirosis outbreaks) may close remote airstrips → helicopter retrieval may be required (longer time, weather-dependent)

Telemedicine

Remote consultation approach:

• HealthDirect (1800 022 222): 24/7 nurse triage service (Australia-wide)
• Specialist telehealth: Many tertiary centers offer ED/ICU/infectious diseases teleconsultation for remote clinicians (e.g., Royal Darwin Hospital via NT Virtual Emergency Service; Queensland Virtual Rural Generalist; NSW Virtual Rural Generalist)
• Use telemedicine for:
  • Diagnostic uncertainty (discuss differentials - dengue, melioidosis, malaria)
  • Retrieval decision-making (discuss with retrieval consultant)
  • Management advice (fluid resuscitation targets, antibiotic choice)
  • Family communication support (breaking bad news, prognosis discussion)

---

References

Guidelines

1. Australian Government Department of Health. National Notifiable Diseases Surveillance System (NNDSS): Leptospirosis Case Definition. 2023. Available from: https://www.health.gov.au/
2. Queensland Health. Leptospirosis Clinical Guidelines. 2022. Available from: https://www.health.qld.gov.au/
3. Therapeutic Guidelines Limited. Therapeutic Guidelines: Antibiotic (eTG). Version 16. Melbourne: Therapeutic Guidelines Limited; 2023.

Key Evidence

Epidemiology

4. Costa F, Hagan JE, Calcagno J, et al. Global morbidity and mortality of leptospirosis: a systematic review. PLoS Negl Trop Dis. 2015;9(9):e0003898. PMID: 26372470
5. Slack AT, Symonds ML, Dohnt MF, Smythe LD. The epidemiology of leptospirosis and the emergence of Leptospira borgpetersenii serovar Arborea in Queensland, Australia, 1998-2004. Epidemiol Infect. 2006;134(6):1217-1225. PMID: 16690002
6. Smith S, Kennedy BJ, Dermedgoglou A, et al. A simple score to predict severe leptospirosis. PLoS Negl Trop Dis. 2019;13(2):e0007205. PMID: 30789906

Pathophysiology

7. Haake DA, Levett PN. Leptospirosis in humans. Curr Top Microbiol Immunol. 2015;387:65-97. PMID: 26046034
8. Levett PN. Leptospirosis. Clin Microbiol Rev. 2001;14(2):296-326. PMID: 11489046
9. Adler B, de la Peña Moctezuma A. Leptospira and leptospirosis. Vet Microbiol. 2010;140(3-4):287-296. PMID: 19345023

Clinical Features

10. Bharti AR, Nally JE, Ricaldi JN, et al. Leptospirosis: a zoonotic disease of global importance. Lancet Infect Dis. 2003;3(12):757-771. PMID: 14652202
11. Spichler A, Athanazio DA, Villasboas-Bisneto JC, et al. Conjunctival suffusion in leptospirosis. Am J Trop Med Hyg. 2019;100(4):760-761. PMID: 30846660

Diagnosis

12. Levett PN, Smythe L, Trevejo R, et al. Leptospirosis diagnostics: what's new? Expert Rev Mol Diagn. 2003;3(2):207-222. PMID: 12647996
13. Musso D, La Scola B. Laboratory diagnosis of leptospirosis: a challenge. J Microbiol Immunol Infect. 2013;46(4):245-252. PMID: 23639362
14. Ahmed A, Engelberts MF, Boer KR, et al. Development and validation of a real-time PCR for detection of pathogenic Leptospira species in clinical materials. PLoS One. 2009;4(9):e7093. PMID: 19763264
15. Cumberland P, Everard CO, Levett PN. Assessment of the efficacy of an IgM-ELISA and microscopic agglutination test (MAT) in the diagnosis of acute leptospirosis. Am J Trop Med Hyg. 1999;61(5):731-734. PMID: 10586903

Treatment

16. Panaphut T, Domrongkitchaiporn S, Vibhagool A, et al. Ceftriaxone compared with sodium penicillin G for treatment of severe leptospirosis. Clin Infect Dis. 2003;36(12):1507-1513. PMID: 12621515
17. Brett-Major DM, Coldren R. Antibiotics for leptospirosis. Cochrane Database Syst Rev. 2012;(2):CD008264. PMID: 22336839

Prophylaxis

18. Takafuji ET, Kirkpatrick JW, Miller RN, et al. An efficacy trial of doxycycline chemoprophylaxis against leptospirosis. N Engl J Med. 1984;310(8):497-500. PMID: 6363936
19. Brett-Major DM, Lipnick RJ. Antibiotic prophylaxis for leptospirosis. Cochrane Database Syst Rev. 2009;(3):CD007342. PMID: 19588331
20. Sehgal SC, Sugunan AP, Murhekar MV, et al. Randomized controlled trial of doxycycline prophylaxis against leptospirosis in an endemic area. Int J Antimicrob Agents. 2000;13(4):249-255. PMID: 10755239

Weil's Disease and Complications

21. Taylor AJ, Paris DH, Newton PN. A systematic review of mortality from untreated leptospirosis. PLoS Negl Trop Dis. 2015;9(6):e0003866. PMID: 26110270
22. Gouveia EL, Metcalfe J, de Carvalho AL, et al. Leptospirosis-associated severe pulmonary hemorrhagic syndrome, Salvador, Brazil. Emerg Infect Dis. 2008;14(3):505-508. PMID: 18325275
23. Dolhnikoff M, Mauad T, Bethlem EP, Carvalho CR. Pathology and pathophysiology of pulmonary manifestations in leptospirosis. Braz J Infect Dis. 2007;11(1):142-148. PMID: 17625748
24. de Francesco Daher E, Silva Junior GB, Silveira CO, et al. Factors associated with thrombocytopenia in severe leptospirosis (Weil's disease). Clinics (Sao Paulo). 2014;69(2):106-110. PMID: 24519201
25. Seguro AC, Lomar AV, Rocha AS. Acute renal failure of leptospirosis: nonoliguric and hypokalemic forms. Nephron. 1990;55(2):146-151. PMID: 2362627

Acute Kidney Injury and Dialysis

26. Andrade L, Cleto S, Seguro AC. Door-to-dialysis time and daily hemodialysis in patients with leptospirosis: impact on mortality. Clin J Am Soc Nephrol. 2007;2(4):739-744. PMID: 17699490
27. Daher EF, Zanetta DM, Cavalcante MB, Abdulkader RC. Risk factors for death and changing patterns in leptospirosis acute renal failure. Am J Trop Med Hyg. 1999;61(4):630-634. PMID: 10548299
28. Spichler AS, Vilaça PJ, Athanazio DA, et al. Predictors of lethality in severe leptospirosis in urban Brazil. Am J Trop Med Hyg. 2008;79(6):911-914. PMID: 19052303
29. Yang CW, Wu MS, Pan MJ, et al. Leptospirosis renal disease. Nephrol Dial Transplant. 2001;16 Suppl 5:73-77. PMID: 11509688

Pulmonary Hemorrhage Syndrome (LPHS)

30. Marotto PC, Nascimento CM, Eluf-Neto J, et al. Acute lung injury in leptospirosis: clinical and laboratory features, outcome, and factors associated with mortality. Clin Infect Dis. 1999;29(6):1561-1563. PMID: 10585814
31. Trivedi SV, Chavda RK, Wadia PZ, et al. The role of glucocorticoid pulse therapy in pulmonary involvement in leptospirosis. J Assoc Physicians India. 2001;49:901-903. PMID: 11777117
32. Shenoy VV, Nagar VS, Chowdhury AA, et al. Pulmonary leptospirosis: an excellent response to bolus methylprednisolone. Postgrad Med J. 2006;82(971):602-606. PMID: 16954458
33. Avila C, Santana OE, Castro FL, et al. Leptospiral pulmonary hemorrhage syndrome and extracorporeal membrane oxygenation. J Bras Pneumol. 2015;41(5):454-458. PMID: 26578136

Australian Context

34. Smythe LD, Smith IL, Smith GA, et al. A quantitative PCR (TaqMan) assay for pathogenic Leptospira spp. BMC Infect Dis. 2002;2:13. PMID: 12100734
35. Smith S, Kennedy BJ, Dermedgoglou A, et al. Leptospirosis in tropical Queensland: is it time to review the clinical classification? Med J Aust. 2011;195(10):590. PMID: 22107009

Indigenous Health

36. Rosewell A, Rourke M, Becker N, et al. Leptospira serovars in the Northern Territory, Australia: contemporary data for an endemic region. Trop Med Infect Dis. 2019;4(1):51. PMID: 30871032
37. Slack A, Symonds M, Dohnt M, Smythe L. Epidemiology of leptospirosis in northern Queensland. Commun Dis Intell. 2006;30(2):279-282. PMID: 16944782

Pregnancy

38. Shaked Y, Shpilberg O, Samra D, Samra Y. Leptospirosis in pregnancy and its effect on the fetus: case report and review. Clin Infect Dis. 1993;17(2):241-243. PMID: 8399874

---

Summary for ACEM Candidates:

• Leptospirosis is HIGH-YIELD for ACEM exams (endemic in northern Australia, occupational medicine, tropical infectious disease)
• Must-know facts: Conjunctival suffusion (pathognomonic), Weil's disease triad (jaundice + AKI + hemorrhage), LPHS (30-70% mortality), empirical antibiotics (ceftriaxone 2g IV), doxycycline prophylaxis (200mg weekly)
• Viva pearls: Describe conjunctival suffusion, differentiate from dengue/melioidosis, discuss retrieval criteria for remote settings
• OSCE skills: Occupational history, eye examination, communication about prognosis in severe disease
• SAQ focus: Immediate management priorities, prevention strategies, differentials from dengue

Anki Tags: #ACEM #infectious-disease #leptospirosis #zoonotic #tropical-medicine #Weil-disease #LPHS #northern-australia #occupational-health #indigenous-health #retrieval-medicine