Dermatology

Scabies

A contagious infestation by Sarcoptes scabiei causing intense nocturnal itch, burrows and a papular rash; cure requires correct whole-body treatment and simultaneous treatment of relevant close contacts.

Definition

Scabies is a contagious infestation by Sarcoptes scabiei var hominis, in which mites burrow into the stratum corneum and trigger an intensely pruritic hypersensitivity eruption. Transmission is mainly by prolonged close skin-to-skin contact; crusted disease has a much higher mite burden and transmission risk.

First principles

The itch is an immune response and may lag behind infestation

Female mites burrow in the stratum corneum and lay eggs. The host's immune response to mite antigens produces intense itch and rash, often several weeks after a first infestation and sooner after re-infestation. Itch can continue for weeks after the mites have been eradicated, so persistent itch alone is not proof of treatment failure.

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