Leprosy is a chronic granulomatous disease
- mycobacterium leprae = intracellular parasite.
- Incubation period
- tuberculoid = 2-5 years
- lepromatous = 8-11 years
- Spread in nasal discharges to the skin or nose.
- Infectivity is low (<10% those exposed show any signs of infection)
Geographical distribution of disease is patchy with 70% cases in India
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.
- Skin lesions
- Thickenned peripheral nerves.
- 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.
*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