What is the treatment for Leptospira infection?

Treatment of Leptospirosis

For mild to moderate leptospirosis, initiate doxycycline 100 mg orally twice daily for 7 days, and for severe leptospirosis (Weil's disease), start intravenous penicillin or doxycycline immediately upon clinical suspicion without waiting for laboratory confirmation. 1, 2

Immediate Treatment Approach

Treatment must begin within 1 hour of recognizing severe leptospirosis, as each hour of delay increases mortality. 1 Do not wait for laboratory confirmation—serologic testing only becomes positive 6-10 days after symptom onset, which is too late for early treatment decisions. 2 Blood cultures are only useful if obtained within the first 5 days before antibiotics. 1, 2

Mild to Moderate Disease (Outpatient)

• Doxycycline 100 mg orally twice daily for 7 days is the recommended first-line treatment 1
• Alternative: Penicillin or other tetracyclines can be effective 1
• Treatment should be started as soon as possible during the bacteremic phase (first 4-7 days of symptoms) 1, 2
• Patients should return if fever does not resolve within 48 hours 1

Severe Disease (Weil's Disease - Hospitalized)

• Intravenous penicillin or doxycycline for 7 days is the standard course 1
• Extend treatment to 10 days in patients with slow clinical response 1
• Start antibiotics within the first hour of recognition of severe sepsis or septic shock 1
• Obtain blood cultures before antibiotics if this causes no delay (<45 minutes), ideally within the first 5 days of illness 1

Supportive Care for Severe Cases

• Fluid resuscitation targeting systolic blood pressure >90 mmHg in adults 1
• Monitor continuously for crepitations indicating fluid overload or impaired cardiac function 1
• ICU admission required for persistent tissue hypoperfusion despite initial fluid resuscitation 1
• Provide renal and liver support as needed 2

Clinical Recognition Triggers

High-Risk Exposure History

• Recreational water sports in fresh water 1
• Occupational exposure to animals or contaminated water 1, 3
• Recent flooding with water contact 1, 2
• Contact with rats, dogs, cattle, or other domestic/wild animals 1, 3

Key Clinical Features

• Conjunctival suffusion (distinctive finding that should immediately raise suspicion) 1, 2
• Biphasic illness pattern: initial bacteremic phase (4-7 days) with high fever (≥39°C), severe calf myalgias, and headache 1, 2
• Jaundice, hemorrhage, and hepato-renal failure in severe cases (5-10% of infections) 1
• Pulmonary involvement with cough and respiratory symptoms (20-70% of cases) 4
• Neurological involvement including aseptic meningitis (19% of cases) 1
• Cardiac involvement (myocarditis/pericarditis) independently predicts severe disease 1

Laboratory Findings

• Proteinuria and hematuria 1
• Leukocytosis with polymorphonuclear cells 1
• Elevated bilirubin with mild transaminase elevation 1
• Alterations in renal function tests 1
• IgM titers >1:320 are suggestive; 1:80-1:160 consistent with early infection 1

Critical Pitfalls to Avoid

• Never delay treatment while awaiting laboratory confirmation—this can lead to life-threatening complications 2
• Do not assume mild symptoms will remain mild—even with treatment, patients can progress to critical illness 2
• Do not discontinue antibiotics early—complete the full 7-day course even with clinical improvement 1
• Do not use doxycycline in children under 8 years—it causes permanent tooth discoloration and enamel hypoplasia with no established alternative 2
• Do not miss the diagnosis by attributing fever and jaundice solely to viral hepatitis—always consider leptospirosis in the differential 1

Prophylaxis Considerations

• Reserve prophylaxis for settings where attack rates exceed 10 cases per 100 person-years 2
• Doxycycline prophylaxis can be used in mass outbreak situations with documented high attack rates 2
• Prophylaxis is contraindicated in children under 8 years 2

Antibiotic Susceptibility

Current antibiotics remain effective against most Leptospira strains, with macrolide and ketolide drugs producing the lowest MICs. 5 All tested agents except chloramphenicol are at least as potent as penicillin and doxycycline. 5