Scabies is an infestation of the skin by the Sarcoptes scabiei mite. It causes generalized intractable pruritus with a characteristic distribution pattern. Risk factors include immunosuppression and crowded living conditions. Scabies is easily transmitted through skin to skin contact. Animal and fomite transmission may also occur.
The Sarcoptes scabiei mite lives in burrowed tunnels in the stratum corneum where it lays its eggs. Burrows are seen as wavy lines on the skin which commonly appear in the digital web spaces, volar wrists, elbows, and genitalia. A rash consisting of papules, nodules, or postules accompanied by eczematous lesions also occurs due to a sensitization reaction against the excreta of the mite. These lesions commonly appear in the digital web spaces, wrists, elbows, axillae, waistline, penis, scrotum, buttocks, and lower extremities.
Treatment consists of topical permethrin or lindane. Oral ivermectin can also successfully treat scabies. The first line treatment is permethrin 5% applied to all areas of the body from the neck down and washed off after 8-12 hours. The symptoms of a scabies infection often persist for several weeks despite effective treatment.