Scabies / Itch Mite

Snapshot

image 298
  • A 2-year-old girl is brought in by her parents due to a rash on her armpit and belly for 2 weeks. Her major complaint is itching. The lesions are so itchy that she cannot sleep at night and scratches her rashes constantly. She goes to daycare 3 days a week. Skin exam reveals multiple polymorphous scaly papules on her hands, in the axilla, and around the umbilicus. A skin scraping with mineral oil prep reveals mites under microscopy.

Introduction

  • Superficial skin infection caused by arthropod Sarcoptes scabiei (mite)
  • Severe itching at night
  • Too small to be seen by naked eye
  • Pathognomonic sign
    • burrows, linear markings in skin due to mites’ movements
  • Risk factors
  • close contacts with scabies

Presentation

  • Symptoms
    • hallmark feature
      • itching worse at night
  • Physical exam
    • adults
      • burrows, especially in between finger web spaces
      • linear markings in skin with some scale
      • erythematous, inflamed pustules and papules
      • commonly on wrist, finger webs, axillae, chest, umbilicus, genital area
    • children
      • generalized pruritic rash
  • scalp may also be involved

Evaluation

image 299
  • Diagnosis based on clinical exam and history
  • Diagnosis confirmed with simple office procedure
    • skin scraping with mineral oil prep
  • can see mites under microscopy

Differential Diagnosis

  • Chiggers 
  • Bedbugs 
  • Contact dermatitis

Treatment

  • Topical permethrin 
  • Sterilize laundry
  • wash/dry all clothing with high heat or throw away

Prognosis, Prevention, and Complications

  • Prognosis
    • very good
  • Prevention
    • avoid those with known scabies
    • treat all known contacts