Leptospirosis: Diagnosis and Treatment
Immediate Clinical Action
For patients with suspected leptospirosis based on exposure history and compatible symptoms, start antibiotic treatment immediately without waiting for laboratory confirmation, as each hour of delay increases mortality. 1, 2
Diagnosis
Key Exposure History (Within Past 2-20 Days)
- Contact with flood water or contaminated fresh water through recreational activities (swimming, canoeing, wading) 2, 3, 4
- Occupational exposure to animals (rats, cattle, pigs, dogs) or contaminated water, particularly in agricultural workers 1, 2, 3
- Contact with soil or water contaminated with animal urine 3, 5
- Recent flooding with water contact 1, 2
Clinical Presentation
Septicemic/Bacteremic Phase (4-7 days):
- High fever (≥39°C) with chills 1, 2
- Severe diffuse myalgias, especially in the calves and inner thighs 1, 6
- Severe headache 1, 2
- Conjunctival suffusion (highly suggestive physical finding) 1, 2
Severe Disease Indicators (Weil's Disease):
- Jaundice 1, 2
- Signs of hemorrhage 2
- Hepatomegaly 2
- Respiratory distress or hypoxemia 2
- Dark red urine (indicating rhabdomyolysis or hemolysis) 6
Laboratory Findings
- Leukocytosis with polymorphonuclear predominance 1
- Thrombocytopenia 1, 4
- Elevated bilirubin with mild transaminase elevation 1
- Acute renal impairment 1, 6
- Proteinuria and hematuria 1
- Elevated CRP 4
- Rhabdomyolysis 6, 4
Diagnostic Testing
Obtain immediately (do not delay treatment):
- Blood cultures (ideally within first 5 days before antibiotics, but do not delay treatment >45 minutes) 1, 2
- Complete blood count 2
- Comprehensive metabolic panel 2
- Urinalysis 2
Confirmatory Testing:
- IgM ELISA: Titers >1:320 are diagnostic; titers 1:80-1:160 suggest early infection 1, 2
- Convalescent serology (MAT): Repeat >10 days after symptom onset; fourfold increase in titer confirms diagnosis 1, 2
- PCR testing: Useful in first week when serology may be negative; turnaround time 1-2 hours 1, 6, 7
Treatment
Mild to Moderate Disease
Doxycycline 100 mg orally twice daily for 7 days 1, 2, 4
Alternative regimens:
Hospitalization criteria:
- Systemic signs of infection, even without severe disease criteria 1
Severe Disease (Weil's Disease)
First-line antibiotic (start within 1 hour of recognition):
- Ceftriaxone 2g IV daily for 7 days 2
Alternative:
- Penicillin G 1.5 million units IV every 6 hours for 7 days 2
Duration:
Supportive Care for Severe Disease
Fluid resuscitation:
- Aggressive IV crystalloid or colloid solution up to 60 mL/kg as three boluses of 20 mL/kg 2
- Target systolic blood pressure >90 mmHg in adults 1
- Reassess after each bolus 2
- Monitor for crepitations indicating fluid overload 1
ICU admission criteria:
- Persistent tissue hypoperfusion despite initial fluid resuscitation 1
- Repeated fluid boluses required 2
- Signs of circulatory failure 2
Respiratory complications:
- Methylprednisolone 0.5-1.0 mg/kg IV daily for 1-2 weeks may be used 2
Monitoring:
Special Populations
Children <8 Years
- Avoid doxycycline due to risk of permanent tooth discoloration 2
- Use penicillin or ceftriaxone instead 2
Post-Flood Prophylaxis
- Doxycycline 200 mg single dose orally provides 76.8% protection 2, 8
- Reserve for high-risk settings only 2
Critical Pitfalls to Avoid
- Do not wait for serological confirmation before starting antibiotics - serology is often negative in the first week 2
- Do not mistake for viral hepatitis in patients with fever and jaundice 1, 2
- Do not discontinue antibiotics early despite clinical improvement - complete the full course 1, 2
- Do not use urine for culture - not suitable for leptospira isolation 2
- Do not delay treatment beyond 4 days of symptoms - effectiveness decreases significantly 1