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DR9.1-6 | Leprosy — Practice Quiz
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A patient presents with 3 hypopigmented skin patches, all with definite anaesthesia. Peripheral nerve palpation reveals an enlarged right ulnar nerve. Slit-skin smear from all sites is negative. Which WHO operational classification applies?
Correct. ≤5 skin lesions with a negative slit-skin smear = WHO Paucibacillary (PB). Both criteria are required.
WHO PB = ≤5 skin lesions AND smear-negative. Both criteria must be met. A negative smear with 3 lesions = PB.
Incorrect. WHO PB requires ≤5 skin lesions AND a negative slit-skin smear. This patient has 3 lesions and a negative smear — both PB criteria are met.
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Which of the following correctly describes the PB-MDT regimen under WHO/NLEP guidelines?
Correct. PB-MDT = Rifampicin + Dapsone × 6 months. Clofazimine is NOT included in PB-MDT.
PB-MDT = Rifampicin + Dapsone for 6 months. No clofazimine. MB-MDT = Rifampicin + Dapsone + Clofazimine for 12 months.
Incorrect. PB-MDT is Rifampicin + Dapsone for exactly 6 months. Remember: PB = 2 drugs × 6 months; MB = 3 drugs × 12 months.
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A 28-year-old presents with 7 erythematous skin patches, decreased sensation over all lesions. Slit-skin smear is negative at all sites. What is the correct WHO operational classification and treatment?
Correct. >5 skin lesions = WHO MB, regardless of smear result. MB-MDT is the 3-drug, 12-month regimen.
7 skin lesions (>5) = MB regardless of smear result. MB-MDT = Rifampicin + Dapsone + Clofazimine × 12 months.
Incorrect. >5 skin lesions classifies as WHO MB. MB-MDT = Rifampicin + Dapsone + Clofazimine × 12 months.
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A patient on leprosy MDT develops sudden tenderness over the right ulnar nerve, new clawing of the right little and ring fingers, and some existing skin patches become more erythematous and slightly raised. There are NO new skin nodules. What type of lepra reaction is this, and what is the first-line treatment?
Correct. Inflamed pre-existing patches + acute neuritis without new nodules = Type 1 (reversal) reaction. First-line = prednisolone (corticosteroids). MDT must be continued.
Type 1 (reversal) reaction: inflamed existing patches + acute neuritis in borderline leprosy (BB/BT/BL). Treatment = corticosteroids. Type 2 (ENL) = new tender nodules in BL/LL. Never stop MDT during reactions.
Incorrect. The key features — inflamed existing patches and acute neuritis without new nodules — define a Type 1 (reversal) reaction. First-line treatment is corticosteroids, and MDT must continue.
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The Ridley-Jopling classification places leprosy patients along a spectrum. Which of the following sequences is correct, from highest to lowest cell-mediated immunity?
Correct. TT → BT → BB → BL → LL represents decreasing cell-mediated immunity and increasing bacterial load.
Ridley-Jopling spectrum: TT (tuberculoid, high CMI, paucibacillary end) → BT → BB → BL → LL (lepromatous, low CMI, multibacillary end). The 'B' prefix = borderline.
Incorrect. The Ridley-Jopling spectrum runs TT → BT → BB → BL → LL, from highest CMI (tuberculoid) to lowest CMI (lepromatous).
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On a slit-skin smear, if BI = 0 at all sites, what does this finding indicate and how does it affect MDT classification?
Correct. BI = 0 means smear-negative. Classification then depends entirely on lesion count: ≤5 = PB, >5 = MB.
BI = 0 = smear-negative. For WHO classification: smear-negative patient with ≤5 lesions = PB; smear-negative with >5 lesions = MB. A negative smear alone does not determine classification — lesion count is equally important.
Incorrect. BI = 0 (smear-negative) does not alone determine PB vs MB classification. Lesion count must also be assessed.
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Which of the following is a WHO cardinal sign of leprosy?
Correct. A hypopigmented or erythematous skin patch with definite sensory loss is one of the three WHO cardinal signs. Any single cardinal sign is diagnostic.
Three WHO cardinal signs of leprosy: (1) hypopigmented/erythematous skin patch with definite loss of sensation; (2) thickened peripheral nerve; (3) acid-fast bacilli on slit-skin smear. ANY ONE is sufficient for diagnosis.
Incorrect. The three WHO cardinal signs are: (1) skin patch with loss of sensation, (2) thickened peripheral nerve, (3) AFB on slit-skin smear. The Lepromin test is used for Ridley-Jopling classification research, not diagnosis.
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A 22-year-old female patient with BL leprosy on MB-MDT develops multiple tender erythematous nodules on the limbs and face, high fever, and arthralgia. What type of reaction is this, and which drug is absolutely contraindicated in her management?
Correct. New tender nodules + fever + arthralgia in BL = ENL (Type 2). Thalidomide is absolutely contraindicated in women who may become pregnant due to severe teratogenicity.
ENL (Type 2 reaction) occurs in BL/LL; new tender nodules + systemic features (fever, arthralgia). Treatment: corticosteroids ± clofazimine. Thalidomide is highly effective but ABSOLUTELY CONTRAINDICATED in women of childbearing age due to severe teratogenicity.
Incorrect. New tender nodules + fever + arthralgia in a BL/LL patient = Type 2 (ENL). Thalidomide is contraindicated in women of childbearing age — corticosteroids ± clofazimine are used instead.
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In the Ridley-Jopling classification, which type of leprosy is most likely to develop a Type 1 (reversal) reaction, and why?
Correct. Borderline patients (BT/BB/BL) have unstable CMI, making them prone to Type 1 (reversal) reactions when their immune balance shifts toward the tuberculoid pole.
Type 1 reactions occur in borderline leprosy (BT/BB/BL) because the CMI is immunologically unstable — it can shift toward the tuberculoid pole (upgrade) with a sudden surge of T-cell activity. TT is stable at the tuberculoid pole; LL is stable at the lepromatous pole.
Incorrect. Type 1 reactions occur in borderline types (BT, BB, BL) due to immunological instability of the borderline zone. TT and LL represent stable poles.
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What staining technique is used for slit-skin smear in leprosy to demonstrate Mycobacterium leprae?
Correct. ZN stain (and the modified Fite-Faraco stain for histopathology) demonstrates M. leprae as acid-fast bacilli — red on blue background.
M. leprae is acid-fast. The standard staining technique for slit-skin smear is Ziehl-Neelsen (ZN) or the modified Fite-Faraco stain (preferred for tissue/histopathology sections as it is more sensitive for M. leprae). Both demonstrate acid-fast bacilli.
Incorrect. M. leprae is an acid-fast bacillus; the appropriate stains are Ziehl-Neelsen or Fite-Faraco. Gram stain, PAS, and Giemsa are not used for AFB identification.
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