Leprosy quiz: answers explained

1. b) Kellgren and Lawrence
   This is a radiological grading system for osteoarthritis, not a leprosy classification. Manila, Pan-American, and Havana are historical leprosy classification systems.
2. a) USG nerve finding
   “Poppy seeds on a muffin” describes the transverse ultrasonographic appearance of a nerve: multiple hypoechoic fascicles surrounded by echogenic epineurium. It is useful when evaluating nerve enlargement in leprosy.
3. b) 5 mm²
   The usual mean cross-sectional area of a normal ulnar nerve at the cubital tunnel is approximately 5 mm². The question prints “mm,” but cross-sectional area should be expressed as mm². Enlargement supports neuritis, though measurements must be compared with the opposite side and interpreted clinically.
4. d) None of the above
   In WHO disability grading, eye grade 1 refers to an eye problem attributable to leprosy, but without severe visual impairment. Inability to close the eye and visible corneal or ocular complications are generally graded as more serious disability. A visual acuity threshold of 6/18 is not the stated grade-1 criterion in this question.
5. d) BCL10
   HLA associations and variants such as PTPN22 have been studied as host-susceptibility factors in leprosy. BCL10 is not a standard established association in the classic leprosy predisposition lists used for examinations.
6. c) Sweating
   Early involvement of autonomic fibers can reduce sweating over a lesion. The patch can become dry before sensory loss becomes obvious. In clinical examination, test sensation carefully, especially light touch, pain, and temperature.
7. a) BT Hansen disease
   A “feeding nerve” entering a lesion is especially associated with borderline tuberculoid (BT) leprosy. It reflects localized neural involvement, often near a well-defined, anesthetic lesion.
8. b) 6 blinks/minute
   This is the quiz key and reflects the examination convention used for assessing facial nerve function in leprosy. In general physiology, spontaneous blink rate varies substantially and is often quoted higher than 6/minute. For this quiz, use 6/minute.
9. a) Median nerve
   The benediction sign appears when a patient with a median nerve palsy tries to make a fist: the index and middle fingers cannot flex properly. It should not be confused with ulnar clawing, which is evident at rest and mainly affects the ring and little fingers.
10. b) Nasal mucosa is usually involved
    This is incorrect. Histoid leprosy, first described by Wade, presents with shiny papules or nodules, sometimes subcutaneous lesions, typically with abundant bacilli. Eyebrows are often preserved. Nasal mucosal involvement is not usual.
11. b) 46 days
    Lepra bacilli can survive for about 46 days in moist soil in experimental observations. This demonstrates environmental survival, but ordinary environmental contact is not considered the principal route of transmission.
12. a) 1-10 solid bacilli
    In the mouse footpad model, a very small inoculum of about 1-10 viable solid-staining bacilli may establish infection. M. leprae cannot be routinely cultured in artificial media, making animal models historically important.
13. d) Ethmoidal sinus
    The ethmoidal sinus is the most commonly involved paranasal sinus in leprosy. This is more relevant in multibacillary disease, where nasal involvement can occur.
14. c) 11-14 days
    Mycobacterium leprae has a slow generation time of approximately 11-14 days, helping explain the long incubation period and indolent course of disease.
15. a) 7-9 days
    Lepra bacilli can survive in dried nasal secretions for 7-9 days under experimental conditions. Transmission in practice is mainly linked to prolonged, close exposure to an untreated infectious case.
16. b) 0.45 per 10,000 population
    This is the answer in the 2024 source quiz and reflects the figure used by its author at that time. It should not be treated as a fixed current figure for India because annual prevalence changes with surveillance and reporting. In an examination, answer 0.45 for this specific published quiz.
17. d) Delhi
    MIP, now known as Mycobacterium indicus pranii, was developed in Delhi, associated with work at the National Institute of Immunology. It has been studied as an immunotherapeutic adjunct and in vaccine-related approaches.
18. c) 6 mg/kg
    The monthly supervised dose of clofazimine in childhood leprosy is 6 mg/kg. Pediatric regimens must follow national or WHO weight-band guidance and maximum-dose limits.
19. a) Rifampicin, clofazimine, and dapsone for 6 months
    WHO recommends a three-drug MDT regimen for paucibacillary disease for 6 months. This uniform regimen includes clofazimine, unlike older PB regimens that used rifampicin plus dapsone only. The WHO leprosy guidance continues to state 6 months for PB and 12 months for MB disease.
20. a) Fitness of the hand for reconstructive surgery
    Bouvier’s manoeuvre helps assess whether passive correction of clawing permits active extension at the interphalangeal joints. It therefore helps decide suitability and select the type of tendon-transfer reconstruction for ulnar palsy.

Additional leprosy quiz questions

1. Which is a cardinal sign of leprosy?

2. Which nerve is commonly palpated behind the medial epicondyle in leprosy?

3. A patient has one anesthetic plaque, asymmetrical nerve thickening, and a negative slit-skin smear. The likely end of the spectrum is:

4. Which immune response predominates in tuberculoid leprosy?

5. Which immune pattern is more typical of lepromatous leprosy?

6. Type 1 lepra reaction is also called:

7. Erythema nodosum leprosum is most closely associated with:

8. A new foot drop in leprosy should be treated as:

9. The main route of transmission of leprosy is thought to be:

10. Which is the standard MDT duration for multibacillary leprosy in WHO guidance?

11. Which drug is responsible for characteristic skin discoloration during MDT?

12. A slit-skin smear is most useful for:

13. Which finding best distinguishes relapse from a lepra reaction?

14. What is the most important measure to prevent disability?

15. Which statement about leprosy after treatment is correct?

Recent advances and current issues in leprosy

1. Uniform three-drug MDT

2. Contact screening plus single-dose rifampicin PEP

3. Zero leprosy strategy, 2021-2030

• Zero infection and disease
• Zero disability
• Zero stigma and discrimination
• Integrated skin-NTD services, early case detection, contact tracing, disability prevention, and rights-based care.

4. Earlier detection of subclinical infection

5. Ultrasound for peripheral nerve assessment

6. Drug-resistance surveillance

7. Vaccines and immunotherapy remain active research areas

8. Relapse requires long-term vigilance

9. Stigma, mental health, and disability care are central

Correct answer: c) Visual impairment of 6/18

• Grade 0: No eye problem due to leprosy and no visual impairment.
• Grade 1: Eye involvement due to leprosy without severe visual loss. Visual acuity of 6/18 is included here.
• Grade 2: Severe ocular disability, such as:
  • Lagophthalmos or inability to close the eye
  • Corneal opacity or corneal ulcer
  • Iridocyclitis
  • Severe visual loss, typically worse than 6/60 or inability to count fingers at 6 metres.

• a) Inability to close the eyes: Grade 2
• b) Obvious redness of eyes: generally treated as a serious visible eye complication in simplified field grading, not the expected Grade 1 answer here
• c) Visual impairment of 6/18: Grade 1
• d) None of the above: incorrect

• a) Inability to close the eyes = lagophthalmos = Grade 2
• b) Obvious redness of eyes = a concerning ocular sign, but it is not by itself the standard defining criterion for WHO Grade 1 in the simplified WHO disability grade
• c) Visual impairment of 6/18 = this is not automatically Grade 1 unless the visual impairment is specifically shown to be due to leprosy. Visual acuity alone does not establish that.

Best exam explanation

• Lagophthalmos is Grade 2.
• A red eye alone is not the defining Grade 1 criterion.
• Visual acuity of 6/18 can only be classified as Grade 1 if the visual loss is confirmed to be due to leprosy. Since the option does not state this, the intended answer is none of the above.