Pathophysiology of Leprosy


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Pathophysiology of Leprosy

  1. 1. Leprosy (Hansen’s Disease) (Lepi: scales on the fish) 1
  2. 2. Discovered by Gerhard Armauer Hansen in 1873 2
  3. 3. Leprosy (Hansen’s disease) is a chronic, systemic infectious disease, affecting primarily the peripheral nerves and secondarily the skin, mucous membranes, the eyes, bones, lymph nodes and viscera. 3
  4. 4.       Chronic granulomatous infection caused by Acid Fast Bacteria Mycobacterium leprae (Ml) Ml cannot be grown on culture media--- in vitro drug sensitivity is not possible Growth and Drug susceptibility are done by injecting inoculate in mouse foot pad Live dormant in macrophages but alive Transmitted from person to person through nose, skin lesions of the infected persons. Affect mainly PNS, NS, Skin and various tissues 4
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  6. 6. Bacteria Resides in Cooler Parts of the Body Skin Peripheral Nerves 6
  7. 7. Mode of infection: Leprosy is slow communicable disease and uncubation period is between first exposure and appearance of signs of disease. Direct contact: Prolonged close contact of susceptible individuals to an open case of leprosy (damaged skin, nasal secretions, mucous membrane contact). Materno- foetal transmission. Transmission from milk from mother to infant. 7
  8. 8. Transmission   Nasal/oral Droplets Dermal Inoculations 8
  9. 9. Armadillo They transmit leprosy  They act as animal model along with monkey, mice and rabbit  9
  10. 10. Incidence At highest risk are those living in endemic areas (hot and moist) with poor conditions such as inadequate bedding, contaminated water, and insufficient diet, or other diseases that compromise immune function.  Acc to WHO- India, Brazil, Indonesia, Myanmar and Nigeria are with the most cases.  10
  11. 11. Classification Main 2 types:  Tuberculoid type: high resistance.  Lepromatous or low resistance  Cass not falling in these 2 are considered as borderline leprosy.  11
  12. 12. Classification Based on the clinical, bacteriologic, immunologic and histopathologic features, leprosy is classified into main types: 1. Paucibacillary example: (Tuberculoid leprosy) (TL) (with scanty or absent bacilli) - Skin lesions, loss of sensation. 2. Multibacillary (Border line) (with numerous bacilli)---numerous skin lesions, loss of sensation, can go to 3. Multibacillary (lepromatous leprosy) (LL). Nodules and plaques, thickened dermis, loss of sensation, neuronal damage, nasal congestion, epistaxis. 12
  13. 13. Symptoms Leprosy attacks the nervous system, particularly the nerves of the hands, feet and face.  In tuberculoid leprosy, skin lesions typically develop in areas of nerve damage. Skin becomes pale, may develop a reddish copper colour.  Lepromatous leprosy: Loss of sensation to pinprick or light touch. Starts at the fingers and toes, affect a small patch of skin to begin with, but as time passes many skin lesions and nodules develop. Organ deformaties  13
  14. 14. Tuberculoid Leprosy The bacilli are usually absent in slit-skin smears. The histopathology shows tuberculoid granulomas composed of epithelioid cells surrounded by a zone of lymphocytes. Lepromin test is strongly positive. 14
  15. 15. Tuberculoid Leprosy 15
  16. 16. Lepromatous Laprosy Cutaneous lesions consist of macules, papules, infiltration or nodules (lepromas). They are numerous, bilateral, symmetrical, ill-defined with shiny surface. The sites commonly affected are the face, arms, legs and buttocks, but may be anywhere. 16
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  18. 18. Diagnosis 1-Clinical symptom diagnosis: (anesthesia, nerve enlargement, and characteristic skin lesions). 2-Slit-skin smears: Ziehl Neelson staining of skin smear. 3-Skin biopsy. 4-Nerve biopsy. 5-Lepromin test. 18
  19. 19. 1. Clinical symptom diagnosis 19
  20. 20. 2. Skin Smear Tests Ziehl Neelsen Carbol Fuchsin Stain (ZNCF) Absence of bacteria in smear: Paucibacillary Presence of bacteria in smear: Multibacillary 20
  21. 21. 3. Lepromin test It is an immunologic test indicative of host resistance to M. leprae. A sample of inactivated (unable to cause infection) leprosy-causing bacteria is injected just under the skin, usually on the forearm Tuberculoid: The immune system recognizes and produces allergic reaction: Positive Lepromatous: The immune system does not recognizes Negative 21
  22. 22. Mechanism of Nerve Damage Entry Through Blood Vessels Inflammatory Response Demyelination 22
  23. 23. Outcomes of Nerve Damage  Sensory Loss  Paralysis  Deformities 23
  24. 24. Classification of Drugs Sulfones: Dapsone (weak bactericidal) MDT: Dapsone + Clofazimine + Rifampicin  Antibiotics: Ofloxacin, Clarithromycin, Minocyclin 24
  25. 25. 1995: WHO Distributes MDT Drugs for Free to Worldwide Patients World leprosy day January 30 in remembrance of 25
  26. 26. 26