Leprosy is caused by which microorganism?

Appeared in: MP CHO-2018

Explanation

Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by the bacterium Mycobacterium leprae.
This bacterium is an acid-fast, rod-shaped bacillus that primarily multiplies in cooler body parts like the skin, peripheral nerves, upper respiratory tract, eyes, and testes.
It was discovered by G.H. Armauer Hansen in 1873, making it the first bacterium identified as causing disease in humans.

Option B: This bacterium causes tuberculosis (TB), a different infectious disease that primarily affects the lungs.
Option C: This is a virus, not a bacterium. It is a leading cause of severe gastroenteritis (diarrhea and vomiting), particularly in infants and young children.
Option D: A mosquito is an insect vector, not a microorganism. It transmits pathogens but does not cause the disease itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Leprosy as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in early detection, patient education about the long-term treatment (Multi-Drug Therapy), and managing skin and nerve damage to prevent disability.
Understanding that leprosy is not highly contagious and is curable helps nurses combat the significant social stigma associated with the disease.
What if the patient presents with a single, well-defined, hypopigmented skin patch with definite loss of sensation? This is a classic sign of paucibacillary (PB) leprosy, which requires a shorter treatment duration (6 months) compared to multibacillary (MB) leprosy (12 months).

How to Approach the Question

First, identify the core of the question, which is to find the specific microorganism causing leprosy.
Analyze the options provided. Options A and B are bacteria of the same genus, Option C is a virus, and Option D is an insect vector.
Recall or deduce the causative agents for common infectious diseases. Mycobacterium is a well-known genus.
Differentiate between M. leprae and M. tuberculosis. M. leprae is specifically associated with leprosy, while M. tuberculosis is associated with tuberculosis.
Eliminate 'Rota virus' as it's known for gastrointestinal illness and 'Mosquito' as it's a vector, not a causative microorganism.
Conclude that Mycobacterium leprae is the correct causative agent for leprosy.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 1445-1447

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 90-92

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 180-182

Practise the full MP CHO-2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.