Leprosy is a chronic granulomatous disease

Organism

  • mycobacterium leprae = intracellular parasite.
  • Incubation period
    • tuberculoid = 2-5 years
    • lepromatous = 8-11 years

 

Transmission

  • Spread in nasal discharges to the skin or nose.
  • Infectivity is low (<10% those exposed show any signs of infection)

Epidemiology

Geographical distribution of disease is patchy with 70% cases in India

Pathogenesis

Bacilli enter through the respiratory tract (usually) and multiply in peripheral Schwann cells (limbs and face)

  • Form of disease determined by level of cell mediated immunity:
  • High levels- tuberculoid disease
  • No/few skin/nerve lesions appear followed by spont. healing.
  • Absent-lepromatous diease
  • Other tissues also become involved (eyes, testes, kidneys, smooth
  • Muscle, reticuloendothelia system and vascular endothelium.

 

Clinical features

  • Skin lesions
  • Parasthesia
  • Thickenned peripheral nerves.

Complications

  • Often thought to cause loss of limbs (“skin falling off”) but in recent times this is less of an issue.
  • Loss of sensation produces loss of protective reactions àresulting in injuryàinfection can develop and in the past (when not caught early) could result in the need for amputation.

Diagnosis

*Early diagnosis is essential in preventing disability*

  • Clinical findings of one or more cardinal signs.
  • Biopsy of skin lesion or nerve.
  • AFBs on slit skin smears

 

Treatment

Multi-drug regimen

  • Rifampicin
  • Dapsone
  • Clofazimine

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