NEET PG High-Yield: Leprosy (Hansen’s Disease)
A chronic granulomatous disease caused by Mycobacterium leprae, primarily affecting skin and peripheral nerves. India has made significant progress toward elimination (defined as < 1 case per 10,000 population).
Classification (Ridley-Jopling)
| Type | Key Features |
|---|---|
| Paucibacillary (PB) | 1–5 skin lesions, no bacilli in slit-skin smear (TT, BT). |
| Multibacillary (MB) | >5 skin lesions, bacilli present in smear (BB, BL, LL). |
Clinical & Treatment Highlights
- Cardinal Signs: Hypopigmented/anesthetic skin patches, thickened peripheral nerves, presence of acid-fast bacilli on slit-skin smear.
- Lepra Reactions: Type 1 (Reversal reaction – cell-mediated, in borderline leprosy) and Type 2 (ENL – humoral, in lepromatous leprosy).
- MDT (Multi-Drug Therapy): Standard regimens include Rifampicin, Dapsone, and Clofazimine.
High-Yield NEET PG Pearls:
- Causative Agent: M. leprae (obligate intracellular, grows at cooler temperatures).
- Nerve Involvement: Ulnar nerve is the most commonly affected nerve in leprosy.
- Treatment Duration: PB (6 months); MB (12 months).
- Lepromin Test: Used for classification and prognosis, not for diagnosis. Positive in TT/BT, negative in LL.
- Clofazimine: Known for causing skin pigmentation (a useful point in counseling patients).