What are the clinical manifestations of leptospirosis?

Clinical Manifestations of Leptospirosis

Leptospirosis presents with a characteristic biphasic illness pattern, beginning with an acute bacteremic phase (4-7 days) featuring high fever, severe calf myalgias, headache, and the distinctive finding of conjunctival suffusion, followed by an immune phase that can progress to severe disease with jaundice, acute renal failure, and hemorrhagic complications in 5-10% of cases. 1, 2

Acute Bacteremic Phase (Days 1-7)

The initial septicemic phase is characterized by:

• High fever (typically ≥39°C) with shaking chills 1, 3
• Severe myalgias, particularly affecting the calf muscles—a highly characteristic feature 1, 2, 3
• Headache (present in approximately 60-80% of patients) 1, 3
• Conjunctival suffusion (bilateral conjunctival redness without discharge)—a distinctive and suggestive clinical sign that should immediately raise suspicion 1, 2, 3

Additional common symptoms during this phase include:

• Nausea and vomiting 4
• Diffuse myalgias beyond the calves 3
• Fever occurs in approximately 90-95% of symptomatic cases 4, 3

Severe Disease Manifestations (Weil's Disease)

Approximately 5-10% of infected individuals progress to severe leptospirosis, characterized by the classic triad of:

• Jaundice (present in 24-40% of hospitalized cases, strongly predictive of severe disease) 1, 4, 3
• Acute renal failure (occurs in approximately 30-50% of hospitalized patients) 1, 4, 3
• Hemorrhagic complications including pulmonary hemorrhage 1, 5

Organ-Specific Complications

Renal manifestations:

• Proteinuria and hematuria on urinalysis 1
• Oliguric acute renal failure requiring dialysis (strongly associated with mortality) 4, 6
• Severe renal impairment (creatinine >500 μmol/L) 3

Hepatic manifestations:

• Marked conjugated hyperbilirubinemia (can exceed 970 μmol/L in severe cases) 6
• Mild elevation of transaminases (disproportionately low compared to bilirubin elevation) 1
• May be misdiagnosed as viral hepatitis 1

Pulmonary manifestations:

• Atypical radiographic findings (present in approximately 25% of cases) 3
• Acute respiratory distress syndrome (ARDS) 3, 5
• Pulmonary hemorrhages 5

Cardiac manifestations:

• Myocarditis or pericarditis (approximately 10% of cases) 3
• Cardiac involvement on clinical examination or ECG is independently predictive of severe disease progression 3

Neurological manifestations:

• Aseptic meningitis (approximately 20% of cases) 3
• Meningoencephalitis (less common) 3

Dermatologic manifestations:

• Rash (approximately 10-20% of cases) 3
• Herpes eruptions 3

Laboratory Findings

Hematologic abnormalities:

• Thrombocytopenia (platelets <140 G/L in approximately 65% of patients) 3
• Leukocytosis with polymorphonuclear predominance 1
• Anemia (particularly if significant hemorrhage occurs) 1, 4

Biochemical abnormalities:

• Elevated bilirubin with disproportionately mild transaminase elevation 1
• Elevated creatinine and blood urea nitrogen 1
• Proteinuria and hematuria 1

Clinical Course and Prognostic Factors

Independent predictors of severe disease and mortality:

• Clinical jaundice at presentation (p=0.005) 3
• Cardiac involvement on examination or ECG (p<0.02) 3
• Requirement for intensive care (odds ratio 2.1, p=0.05) 4
• Requirement for dialysis (odds ratio 39.66, p=0.03) 4
• Preexisting chronic liver disease 4
• History of alcoholism 4

Critical Clinical Pitfalls

Delayed diagnosis occurs due to:

• Non-specific initial presentation mimicking viral illness 1, 2
• Misdiagnosis as viral hepatitis in patients presenting with fever and jaundice 1
• Failure to obtain exposure history (occupational, recreational water contact, flood exposure) 2, 7
• Waiting for laboratory confirmation before initiating treatment (serologic testing only becomes positive 6-10 days after symptom onset) 2

The biphasic pattern is characteristic: After the initial bacteremic phase, patients may experience temporary improvement before developing the immune phase with potential organ failure 2. Assuming mild symptoms will remain mild is a dangerous error, as progression to severe disease can occur rapidly even with treatment 2.