Scabies

Background

• Sacoptes scabiae var. hominis
• Female burrows through skin (finger webs, elbows, wrists)
• 2-3 eggs per day in burrow (for up to 2 months!)
• Larvae emerge 3 days later
• Live cycle complete in 10-14 days. Mites live circa 30 days
• Incubation period (1st) 2-4 weeks - allergic reaction develops to mite faeces

Clinical

• Itch , rash, papules
• Scratching and eventual lichenification
• Hands,(finger webs), wrists, elbows, male genitalia, buttocks, axillae.
  • ( In contrast allergic Rxn usually midriff, inside thighs axillae, legs)

Diagnosis

• Hx often very persuasive!
• ID burrow with mite at one end (good light, magnifying glass)
• Crusted ("Norwegian") scabies found in elderly, alcoholics, Down's syndrome, AIDS, immunosuppressed

Treatment

• Oral antihistamines (itch) if required
• Permethrin (or malathion)
• Household contacts treated AT SAME TIME
• Two treatments, one week apart
• Asymptomatic contacts (> 10 minutes contact) need one treatment

Notes

• Anybody else at home got itch?
• 80% of males have genital involvement
• No head / neck involvement as too cold
• Don’t look for burrows treat on Hx alone. GP to refer dermatology if fails

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