What are the clinical signs and symptoms of leptospirosis?

Clinical Signs and Symptoms of Leptospirosis

Leptospirosis typically presents as a biphasic illness beginning with an acute septicemic phase lasting 4-7 days, characterized by high fever (≥39°C), severe calf myalgias, headache, and the pathognomonic sign of conjunctival suffusion, followed by an immune phase that may progress to severe disease with jaundice, renal failure, and hemorrhagic complications in 5-10% of cases. 1, 2

Septicemic (Acute) Phase

The initial phase occurs 7-12 days after exposure (range: 2-30 days) and lasts 4-7 days 3, 1:

• High fever (usually ≥39°C) with rigors and chills 1, 4
• Diffuse myalgias, particularly severe in the calves—a highly characteristic feature 1, 4
• Severe headache (present in most patients) 1, 4
• Conjunctival suffusion (conjunctival redness without discharge)—a suggestive and relatively specific sign when present 1, 4

Additional common manifestations during this phase include:

• Nausea, vomiting, and diarrhea 4
• Abdominal pain 4
• Rash (occurs in approximately 18% of cases) 4
• Herpes labialis eruption 4

Immune Phase and Severe Disease

After the initial septicemic phase, patients may develop immune-mediated complications 2, 5:

Weil's Disease (Severe Form—5-10% of cases)

The classic triad of severe leptospirosis includes 1, 2:

• Jaundice (present in 24 of 62 patients in one series; independently predictive of severe disease) 4
• Acute renal failure (occurs in approximately 53% of hospitalized cases, sometimes requiring dialysis) 4
• Hemorrhagic manifestations (thrombocytopenia in 65.5% of cases with platelets <140 G/L) 4

Organ-Specific Manifestations

Pulmonary involvement (20-70% of patients) 2:

• Cough and respiratory symptoms 2
• Atypical radiographic findings 4
• Acute respiratory distress syndrome (ARDS) in severe cases 4
• Hemorrhagic pneumonia 6

Cardiac involvement (independently predictive of severe disease) 4:

• Myocarditis or pericarditis 4
• ECG abnormalities 4

Neurological involvement 2, 4:

• Aseptic meningitis (occurs in approximately 19% of cases) 4
• Meningoencephalitis (less common) 6, 4

Renal manifestations 1:

• Proteinuria and hematuria on urinalysis 1
• Elevated creatinine (sometimes >500 μmol/L in severe cases) 4

Ocular involvement 2:

• Uveitis (typically occurs during immune phase) 2

Laboratory Findings

Key laboratory abnormalities that support the diagnosis 1:

• Leukocytosis with predominance of polymorphonuclear cells 1
• Thrombocytopenia (present in 65.5% of cases) 4
• Elevated bilirubin with only mild elevation of transaminases (distinguishing feature from viral hepatitis) 1
• Alterations in renal function tests 1
• Anemia if significant hemorrhage has occurred 1

Clinical Pitfalls and Key Diagnostic Considerations

Leptospirosis may be misdiagnosed as viral hepatitis in patients presenting with fever and jaundice—the key distinguishing feature is that leptospirosis causes elevated bilirubin with only mild transaminase elevation, whereas viral hepatitis causes marked transaminase elevation 1.

The classic presentation is often absent at initial presentation—many patients present with nonspecific flu-like symptoms, making early diagnosis challenging 7, 6. The disease can present without a typical prodromal period, further complicating diagnosis 6.

Independent predictors of severe disease requiring intensive care include 4:

• Clinical jaundice (p=0.005)
• Cardiac involvement on clinical exam or ECG (p<0.02)
• History of chronic liver disease or alcoholism 7
• Requirement for dialysis (odds ratio 39.66) 7

High-risk exposure history is critical for diagnosis 3:

• Recreational water sports in fresh water 3
• Occupational exposure to animals or contaminated water 3
• Recent flooding with water contact 3
• Contact with rats, dogs, cattle, or other domestic/wild animals 3, 2