Paucibacillary leprosy — DTM&H MCQ

Correct answer: D — Paucibacillary leprosy multidrug therapy

The correct answer is D, paucibacillary leprosy multidrug therapy. This patient has three hypopigmented, anaesthetic patches with a single thickened nerve (common peroneal) and negative slit-skin smears, which fits the WHO operational classification of paucibacillary (PB) leprosy: <cite index="1-1">patients showing negative smears at all sites are said to have paucibacillary leprosy (PB), while those showing positive smears at any site are said to have multibacillary leprosy (MB)</cite>. Loss of sensation within the patches plus nerve thickening confirms leprosy rather than a simple pigmentary skin disorder. Because smear negativity and limited lesion number (fewer than six patches, one nerve) define PB disease, the shorter PB regimen (rifampicin and dapsone) is indicated rather than the longer MB regimen. Monotherapy is avoided in all leprosy because <cite index="1-2">treatment of leprosy with only one anti leprosy drug (monotherapy) will result in development of drug resistance to that drug</cite>. Why the other options are wrong: B. Multibacillary leprosy therapy because smears are negative: this reverses the classification rule; negative smears with limited lesions define paucibacillary, not multibacillary, disease, so the longer MB regimen (adding clofazimine, extended duration) is unnecessary and exposes the patient to avoidable drug toxicity. A. Single-dose ivermectin: this treats scabies or strongyloidiasis, not leprosy, and has no activity against Mycobacterium leprae. E. Topical antifungal therapy: hypopigmented patches from tinea versicolor lack sensory loss and nerve thickening, and topical antifungals do nothing for a mycobacterial infection with neural involvement. C. Rifampicin monotherapy: single-agent treatment risks selecting rifampicin-resistant M. leprae and is never recommended for any leprosy classification. Key point: Classify leprosy for treatment using lesion count and smear status (five or fewer lesions, negative smears, one nerve equals paucibacillary), never smear result alone dictating multibacillary status, and always use combination MDT to prevent resistance.

Reference: WHO, Leprosy (Hansen's disease), South-East Asia Region health topic page, 2019: https://www.who.int/southeastasia/health-topics/leprosy