(X)MicroB Bacteria Mycobacterium (1)leprae

Question 1

What is Hansen’s disease?

Answer 1

Leprosy

characteristic clawed hands + peripheral nerve damage + wasting,muscle weakness

Question 2

Mycobacterium leprae infection

Transmission
Close/prolonged contact (respiratory route probably)

Pathogenesis of Leprosy

[…]

Clinical Presentations (Leprosy) (Ridley Jopling System)

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Answer 2

Mycobacterium leprae infection

Transmission
Close/prolonged contact (respiratory route probably)

Pathogenesis of Leprosy

• M. leprae target Schwann cells of peripheral nerves, causing nerve damage
• Depending on patient’s immune response to infection, clinical presentations may vary (below)

Clinical Presentations (Leprosy) (Ridley Jopling System)

1. Tuberculoid leprosy (predominant TH1 (cell-mediated) response)
   - 1 or 2 hypopigmented skin lesions
   - Thickening of peripheral nerves
   - Biopsy of skin lesions rarely show any bacilli
2. Lepromatous leprosy (predominant TH2 (humoral) response due to absent cell-mediated immune response)
   - Dissemination of AFB (nasal & pharyngeal mucosa, eye, muscles, testicles, bone marrow)
   - Intense edema of affected tissue
   - Facial lip swelling with collapse of nose bridge (leonine facies)
   - Biopsy of infected tissues show undifferentiated macrophages packed with AFBs
   - Highly infectious due to nasal discharge
3. Borderline leprosy (Balanced TH1 + TH2 response)
   - Lymphocytic infiltrate and epithelioid cells but no giant cells
   - Unstable form of disease, changes either way with small fluctuations in immune response

Just 1 card cuz its really not that important for SG context