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Aetiology and Pathogenesis

In common scabies there are few mites probably because of scratching destroys the burrows. In some patients skin anaesthesia secondary to neuropathy or spinal injury obviously do not perceive itch and do not scratch crusted scabies is likely to develop.


Crusted scabies has a predilection for patients with physical debilitation, mental retardation, sensory impairment and immunosuppression.

  1. Clinical Features
    Masses of horny debris accumulate beneath thickened and discoloured nails. Large warty crusts form on the hands and feet, and the palms and soles may be irregularly thickened and fissured. Itching is often absent or slight. It may present as exfoliative dermatitis. Differential diagnoses include hyperkeratotic eczema, psoriasis, Darier's disease and contact dermatitis.
  2. Treatment
    1. There is no single treatment for crusted scabies. The general principle is that multiple treatment is needed and sequential use of several agents may be necessary. The following regimen is suggested with the use of 25% benzyl benzoate emulsion (BBE), Ivermectin, given in a single oral dose, is found to be effective in healthy and HIV subjects in a small study.
    2. 0.5% Malathion is a good alternative which is also effective and causing less irritation. Crotamiton is an alternative to malathion to the area, but is much less effective.
    3. Repeat the above steps for 4 consecutive days at least.
    4. Repeat examination and isolation for mite on day 5. Continue treatment until identification is negative.
    5. Give oral antibiotics for 7-10 days.
  3. Management Of Contacts:
    Adequate treatment of contacts is as important as adequate management of the target patient. Success of treatment depends on an all-inclusive approach: all individuals in the ward and their family members should be treated, and treated simultaneously, no matter whether they are symptomatic or asymptomatic.
  4. Pediculosis Capitis, Pubis & Corporis


intensely pruritic red excoriations, morbilliform rash

  1. scalp lice: nits on hairs
    red excoriated skin with secondary bacterial infection, lymphadenopathy
  2. pubic lice: nits on hairs
    “maculae ceruleae”= bluish macules over buttocks and thighs.


rarely in chronic cases:

grey, pea-sized macules

  1. body lice:
    1. Nits and lice in seams of clothing
    2. Excoriations and secondary infection
    3. Mainly on shoulders, belt-line and buttocks
  1. Treatment
    1. Permethrin 1% cream rinse (ovicidal)
    2. for body lice, washing clothes is essential

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