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Abstract
Crusted scabies is a rare form of infestation with Sarcoptes scabiei, leading to thickening of the horny layer of the epidermis colonised by mites. This condition, originally described by Danielssen and Boeck in 1848 in Norwegian patients with Hansen's disease, is also known as Norwegian scabies. The term crusted scabies is more useful than Norwegian scabies since there is no association with Norway. This condition has been described in patients with mental illness.1 Down's syndrome is a recognised association. It is unclear whether absence of pruritus, immobility, or impaired cellmediated immune response is responsible for the hyperkeratotic changes. Crusted scabies, in contrast to ordinary scabies, occurs more frequently in immunosuppressed individuals. It has been found in people with AIDS(2) and in human T-cell lymphotropic virus type 1 (HTLV-1) seropositive patients who developed adult T-cells leukaemia or lymphoma.3 Druginduced immunosuppression,1 renal transplant recipients,4 or prolonged topical treatment with steroids,5 are associated with a higher incidence of crusted scabies.