Leptospirosis Prophylaxis After Flood Exposure
Immediate Recommendation
For adults and children ≥8 years exposed to flood water in leptospirosis-endemic areas, administer doxycycline 200 mg as a single dose for post-exposure prophylaxis, particularly if exposure occurred within the past few days and especially if the person has any open wounds or lacerations. 1, 2, 3
Who Should Receive Prophylaxis
High-Risk Individuals Requiring Treatment:
- Adults and children ≥8 years with direct contact with flood water, particularly those with:
Age-Specific Contraindications:
- Children under 8 years should NOT receive doxycycline due to risk of permanent tooth discoloration and enamel hypoplasia 2
- For this age group, focus on prevention measures and early recognition of symptoms rather than chemoprophylaxis 2
Prophylaxis Regimen
Standard Dosing:
- Single dose: 200 mg doxycycline orally 3
- This single-dose regimen showed 76.8% protective efficacy against leptospiral infection and 86.3% against clinical leptospirosis in flood victims 3
- For those with laceration wounds, efficacy increases to 92% for infection and 95.6% for disease 3
Alternative for Extended High-Risk Exposure:
- Weekly doxycycline 200 mg can provide short-term protection in settings where attack rates exceed 10 cases per 100 person-years 2, 4
- This is typically reserved for military exercises or prolonged occupational exposures in highly endemic areas 2
Improving Compliance:
- Administer doxycycline with food (the "BreaDoxy sandwich" method) to reduce drug-induced gastritis and improve compliance 5
When Prophylaxis Is Most Effective
Timing is critical: Prophylaxis works best when administered soon after exposure, ideally within days of flood contact 3. The protective benefit is highest in those with:
- Recent exposure (within past few days) 3
- Open wounds or skin breaks at time of water contact 3
- Limited duration of exposure (≤3 hours daily showed 89.2% efficacy) 3
Mass Prophylaxis Campaigns
In outbreak situations following severe flooding:
- Large-scale doxycycline distribution can be implemented to limit morbidity and mortality 6
- A 3-week chemoprophylaxis campaign in Guyana reached over 280,000 people following severe flooding and confirmed leptospirosis outbreak 6
- Mass campaigns are justified when there is documented high attack rate and widespread flood exposure 6
Prevention Measures (All Ages)
Since prophylaxis has limitations, emphasize these prevention strategies:
Primary Prevention:
- Avoid contact with flood water whenever possible, especially if you have cuts or abrasions 1, 2
- Use protective equipment (waterproof boots, gloves) during unavoidable water contact 2
- Avoid swimming or wading in water likely contaminated with animal urine 7
Wound Care:
- Cover all cuts and abrasions with waterproof dressings before any flood water exposure 8
- Clean any wounds immediately after contact with flood water 8
Early Recognition of Disease
Educate exposed individuals to seek immediate medical care if they develop:
- High fever (≥39°C) with chills within 2-30 days of exposure 1
- Severe calf muscle pain (highly suggestive) 1
- Headache and conjunctival suffusion (red eyes without discharge) 1
- Jaundice 1
If symptoms develop, start treatment immediately with doxycycline 100 mg twice daily or IV penicillin for severe cases, without waiting for laboratory confirmation 1, 9. Treatment initiated after 4 days of symptoms is less effective, making early recognition critical 1.
Common Pitfalls to Avoid
- Do NOT give doxycycline to children <8 years under any circumstances for flood exposure 2
- Do NOT delay treatment if clinical leptospirosis develops while waiting for serology confirmation 1, 9
- Do NOT assume prophylaxis provides complete protection—it reduces but does not eliminate risk, so prevention measures remain essential 3
- Do NOT use prophylaxis as substitute for protective equipment in ongoing high-risk occupational settings 2