ICD-11

A highly contagious infestation of the skin by the mite Sarcoptes scabiei var. hominis. It may result in epidemics when introduced into institutions such as schools and nursing homes. The mites burrow into the skin, favouring the extremities, genitalia and, in infants, the axillae. The characteristic widespread intensely pruritic papulovesicular rash results largely from the host response rather than directly to burrowing by mites. Where such a response is absent as in immunosuppressed or debilitated patients, unchecked proliferation of mites results in crusted scabies. Sarcoptic mites from other mammals such as dogs may cause a transient pruritic eruption.

An infestation of the skin by the human scabies mite, Sarcoptes scabiei var. hominis, which is passed from human to human by close skin contact. The mites burrow into the epidermis and thereby excite a host immune response which limits the extent of the infestation but results in a widespread inflammatory eruption of intensely pruritic papules. These frequently become secondarily infected as a result of excoriation. In individuals who fail to mount an immune response, the mites may proliferate unchecked with the formation of extensive crusts containing enormous numbers of mites (crusted scabies).

Crusted scabies results from unchecked proliferation of the human scabies mite in individuals who are unable to mount an adequate immune response to infestation. Extensive thick crusts containing vast numbers of mites form over the skin, particularly of the extremities. Because itching is usually absent, the diagnosis is frequently overlooked. Patients with crusted scabies may serve as the source for widespread outbreaks of scabies in institutions such as hospitals and care homes.