Duration of Multi-Drug Therapy (MDT) for Leprosy
For paucibacillary (PB) leprosy, treat with 6 months of fixed-duration MDT; for multibacillary (MB) leprosy, treat with 12 months of fixed-duration MDT, as recommended by WHO. 1, 2
Paucibacillary (PB) Leprosy Treatment Duration
The standard treatment duration is 6 months of fixed-duration MDT. 1, 3, 4
- The 6-month regimen consists of monthly supervised rifampicin 600 mg plus daily dapsone 100 mg 1, 2
- This fixed duration achieves a 91% cure rate with relapse incidence of only 1.3 per 100 person-years 3
- Treatment completion rates reach 90.8% with this regimen 4
- The incidence of disability remains low at 0.50 per 100 person-years in treatment-completed patients 3
Key consideration: Even if skin lesions remain clinically active at the end of 6 months (occurs in approximately 30% of cases), continue follow-up rather than extending treatment—lesions typically become inactive within 2 years post-treatment in 99% of patients 4
Multibacillary (MB) Leprosy Treatment Duration
The standard treatment duration is 12 months of fixed-duration MDT. 1, 2, 5
- The WHO-recommended 12-month regimen consists of monthly supervised rifampicin 600 mg plus clofazimine 300 mg, with daily dapsone 100 mg and clofazimine 50 mg 1, 2
- This represents a reduction from the previous 24-month duration, providing operational advantages while maintaining efficacy 6
- The bacteriological index (BI) decreases at a mean annual rate of 0.50, with 98.7% achieving smear negativity by 6 years post-treatment 5
Alternative shorter regimen (investigational): A 12-week regimen using daily rifampicin 600 mg, sparfloxacin 200 mg, clarithromycin 500 mg, and minocycline 100 mg achieved 73.92% clinical improvement and comparable BI reduction to standard 12-month therapy, though this requires further validation 6
Post-Treatment Monitoring
Continue surveillance after completing MDT to detect the rare relapse or late-onset disability. 3, 5
- Follow patients annually for at least 6 years after treatment completion 5
- Relapse rates remain low (approximately 1-2%) but do occur, typically within the first 2 years 3
- Monitor for leprosy reactions, which can occur during and after treatment 5
Special Populations and Dosing Adjustments
For children, reduce doses proportionally while maintaining the same treatment duration. 1
- Dapsone resistance requires switching to alternative drugs (ofloxacin, minocycline, clarithromycin) rather than extending duration 1, 2
- In lepromatous and borderline lepromatous patients with proven dapsone resistance, continue alternative regimens for life after achieving clinical control 1
Common Pitfalls to Avoid
- Do not extend PB treatment beyond 6 months based solely on persistent skin lesions—this represents normal healing kinetics, not treatment failure 4
- Do not use dapsone monotherapy—this leads to drug resistance and treatment failure 2
- Do not interrupt MDT—maintain full dosage without interruption to prevent secondary resistance 1
- Do not confuse leprosy reactions with treatment failure—reactions are immunological phenomena that may require corticosteroids but not treatment extension 5