What is the recommended prophylaxis dose for asymptomatic contacts of leprosy?

Prophylaxis for Asymptomatic Leprosy Contacts

Single-dose rifampicin 600 mg is the recommended post-exposure prophylaxis for asymptomatic contacts of leprosy patients, administered once after contact screening confirms absence of disease. 1

Standard Prophylaxis Regimen

The World Health Organization endorses single-dose rifampicin (SDR) as the established prophylactic intervention for leprosy contacts, demonstrating a 60% reduction in disease risk. 2, 1 This regimen has been successfully implemented across multiple countries including Brazil, India, Indonesia, Myanmar, Nepal, Sri Lanka, and Tanzania, with 151,928 contacts receiving SDR out of 174,782 screened (86.9% administration rate). 1

Dosing Specifications

• Adults: Rifampicin 600 mg as a single oral dose 2, 1
• Children: Weight-adjusted rifampicin dosing (specific weight-based adjustments should follow standard pediatric rifampicin guidelines) 3, 4

Implementation Algorithm

Step 1: Contact Identification and Tracing

• Trace all household contacts and immediate neighbors (typically 5 neighboring houses) of newly diagnosed leprosy patients 2
• The LPEP programme successfully traced 97.2% of listed contacts, demonstrating high feasibility 1

Step 2: Screening for Active Disease

• Screen all traced contacts for clinical signs of leprosy before administering prophylaxis 1
• Among screened contacts, approximately 0.5% will have undiagnosed active leprosy (46 per 10,000 contacts screened) 1
• Contacts with confirmed leprosy should receive full multidrug therapy, not prophylaxis 5

Step 3: Assess Eligibility for SDR

• Exclude contacts with active leprosy, significant health contraindications, or age-related concerns 1
• Approximately 13.1% of screened contacts will be ineligible, primarily due to health reasons and age 1
• No serious adverse events have been reported with SDR prophylaxis 1

Step 4: Administer Single-Dose Rifampicin

• Provide SDR to all eligible contacts after screening 1
• Refusal rates are low (0.7% among eligible contacts) 1

Enhanced Prophylaxis Regimens Under Investigation

While SDR remains the current standard, enhanced regimens are being studied to improve the 60% efficacy rate:

• PEP++ regimen: Three doses of rifampicin 600 mg plus moxifloxacin 400 mg given at four-weekly intervals, targeting 80-90% risk reduction 3
• Alternative for children or adults with moxifloxacin contraindications: Rifampicin 600 mg plus clarithromycin 300 mg (weight-adjusted) 3
• Bedaquiline-enhanced PEP: Single-dose bedaquiline 800 mg combined with rifampicin 600 mg showed comparable safety to rifampicin alone in a Phase 2 trial, though this remains investigational 4

Critical Implementation Considerations

Timing: Prophylaxis should be administered promptly after contact screening, as the intervention targets early preclinical infection. 2 The limited 60% effectiveness of SDR likely reflects that some contacts have progressed beyond early infection stages where single-dose therapy is insufficient. 3

Safety Profile: SDR prophylaxis has an excellent safety record with no serious adverse events reported across large-scale implementation involving over 150,000 contacts. 1 This makes it highly suitable for mass administration in contact tracing programs.

Programmatic Integration: The "drives" approach—where trained teams systematically contact all eligible index cases in a district, trace contacts, screen them, and administer SDR—has proven feasible even in low-endemic settings like Cambodia. 2 This systematic approach achieved 72% contact screening rates despite logistical challenges. 2

Common Pitfalls to Avoid

• Do not administer prophylaxis without screening: Always screen contacts for active disease first, as approximately 0.5% will have undiagnosed leprosy requiring full treatment rather than prophylaxis 1
• Do not use dapsone for prophylaxis: While dapsone 100 mg daily is used for leprosy treatment 6, 5, single-dose rifampicin is the established prophylactic agent for contacts 1
• Do not delay contact tracing: Retrospective active case finding combined with SDR administration is effective even for patients diagnosed years earlier (since 2011 in the Cambodia program) 2