Scabies
Scabies is an intensely pruritic skin infestation with the mite Sarcoptes scabiei, transmitted by close skin-to-skin contact and classically involving the finger web spaces, wrists, axillae, and genitals while sparing the face and scalp in adults. Diagnosis is clinical, confirmed by mineral oil microscopy when needed, and treatment is topical permethrin or oral ivermectin with simultaneous treatment of contacts.
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What this article covers
- Overview
Scabies is an infestation of the epidermis by the mite Sarcoptes scabiei, producing an intensely pruritic eruption from direct mite burrowing plus a hypersensitivity reaction to the mite, its eggs, and its fecal pellets (scybala).
- Epidemiology
Occurs in patients of all ages, though outbreaks cluster in settings with close, sustained physical contact.
- Risk factors
Close, prolonged skin-to-skin contact with an infested person, including household, institutional, and sexual contact, is the dominant risk factor for classic scabies.
- Pathophysiology
The female mite burrows into the stratum corneum of the epidermis, laying eggs along the burrow track and depositing fecal pellets (scybala) as she moves.
- Clinical features
Intense pruritus, characteristically worse at night and after a hot shower, is the hallmark presenting symptom and often the clue that distinguishes scabies from other pruritic dermatoses even before the rash is fully characterized.
- Differential diagnosis
Atopic dermatitis/eczema: flexural pruritus that overlaps in distribution but lacks burrows and instead has a chronic relapsing course with a personal/family atopic history.
- Diagnosis
Scabies is a clinical diagnosis established by the combination of intense, nocturnally worse pruritus, the classic burrow/papule distribution (web spaces, wrists, axillae, umbilicus, genitals, with…
- Management
Treat every diagnosed patient and, simultaneously, all household members and close physical contacts, regardless of symptoms, because asymptomatic incubating infestation and reinfection from an…
- Complications
Secondary bacterial skin infection (impetigo, cellulitis, or post-streptococcal glomerulonephritis) from scratching-induced breaks in the skin barrier is the most significant complication of ordinary scabies.
- Prognosis
Excellent with appropriate treatment of the patient and close contacts, with mite eradication expected after a properly timed two-dose regimen of permethrin or ivermectin.
- Prevention
Treat all household members and close physical/sexual contacts simultaneously with the index case, even if asymptomatic, since the incubation period before symptomatic itch allows silent transmission.
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