USMLE

Sarcoptes scabiei (Scabies)

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Parasites
  1. Giardia lamblia
  2. Toxoplasma gondii
  3. Entamoeba histolytica
  4. Cryptosporidium
  5. Naegleria fowleri
  6. Trypanosoma brucei
  7. Plasmodium Overview
  8. Plasmodium Disease (Malaria)
  9. Babesia
  10. Trypanosoma cruzi
  11. Leishmania
  12. Trichomonas vaginalis
  13. Enterobius vermicularis (pinworm)
  14. Ascaris lumbricoides (giant roundworm)
  15. Strongyloides stercoralis (threadworm)
  16. Ancyclostoma and Necator
  17. Trichinella spiralis
  18. Trichuris trichiura (whipworm)
  19. Toxocara canis
  20. Onchocerca volvulus
  21. Loa loa
  22. Wuchereria bancrofti
  23. Taenia solium
  24. Diphyllobothrium latum
  25. Echinococcus granulosus
  26. Schistosoma
  27. Clonorchis sinensis
  28. Sarcoptes scabiei (Scabies)
  29. Pediculus humanis and Phthirus pubis (Lice)

Summary

Sarcoptes scabiei is an ectoparasite that causes scabies. The parasite lives on top of the skin and burrows under the skin at flexor surfaces, causing symptoms like pruritic rash and linear burrows. This mite is transmitted mainly by skin-to-skin contact, though it can also be transferred through objects like fabric clothing or bedding. Permethrin in a cream formulation is the first line treatment for scabies.

Key Points

  • Sarcoptes scabiei 
    • Characteristics
      • Ectoparasite (mite)
    • Transmission
      • Direct skin-to-skin contact (most common) or via fomites
    • Presentation: Scabies
      • Pruritic rash
        • Type IV hypersensitivity reaction against mites burrowing into skin
        • May be worse at night
        • Involve flexor surfaces/skin folds of wrist, lateral surfaces of fingers, finger webs, genitals, umbilicus, etc.
      • Linear burrows 
    • Diagnosis
      • Skin scrapings with mineral oil prep
        • Mites, ova, feces identified in microscopy
    • Treatment
      • Permethrin cream