Scabies



Sarcoptes scabiae - Thank You to NEJM
Scabies burrows often found in finger web spaces

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.


Content by Dr. Íomhar O' Sullivan 14/03/2009. Last review Dr. ÍOS 5/05/15.