GP - Scabies (patient)

Question 1

What is Scabies?

Answer 1

Scabies is caused by infestation of the skin by the mite Sarcoptes scabiei

• Highly contagious - mainly spreads via skin-to-skin contact
• Typically affects children / young adults
• Mites lay eggs in the stratum corneum of skin (outermost layer of the epidermis)
• Pruritis is due to delayed-type IV hypersensitivity reaction to the mites/eggs (this occurs ~ 30 days after initial infection)

Question 2

What are the features of Scabies?

Answer 2

Features of Scabies:

• Intense pruritis
• Hx of itching in household / close contacts
• Overcrowded living
• Linear erythmatous burrows/papules/nodules
  
  • Found on fingers, flexor aspect of wrist, interdigital web spaces, axillae, abdomen and penis (common in areas of skin folds)
  • Look like grey lines with a small black dot at the end
  • In infants –> face + scalp can be affected
• Secondary complications:
  
  • Infection - due to scratching of infested areas
  • Strep infection can cause –> rheumatic heart disease or post-streptococcal glomerulonephritis

Question 3

How is Scabies managed?

Answer 3

• 1st line = Topical permethrin 5% or Oral Ivermectin
• 2nd line = Topical malathion 0.5%
• Topical advise:
  
  • Apply topical cream to cool, dry skin
  • Apply topical cream to all areas of skin, including face + scalp
  • Pay close attention to between fingers & toes, armpits and creases of skin
  • Allow to dry for 8-12 hrs for permethrin or 24 hrs for malathion –> then wash off
  • Reapply if cream is removed during treatment window e.g. accidentaly wash hands, nappy change etc.
  • May need to repeat treatment 1-2 weeks later
  • Pruritis can persists for 4-6 weeks post eradication

Question 4

Where in the skin do Scabies mites burrow / lay eggs?

Answer 4

Stratum corneum

(outermost layer of epidermis)

Question 5

What advise would you give a patient with Scabies to prevent re-infestation or spread to other people?

Answer 5

1. Avoid close physical contact with others until treatment is complete
2. All household + close physical contacts need to be treated simultaneously
3. Kill mites - Launder + tumble dry + iron all clothing, bedding, towels etc on 1st day of treatment

Question 6

What type of Scabies can immunocompromised patients suffer from?

Answer 6

Crusted (also called Norwegian) Scabies

• Often seen in immunocompromised or immunosuppressed pts (especially HIV)
• Is a highly contagious and severe form of scabies
• Dense erythmatous scaly plaques on extremities + torso
• Dystophic nails (altered nail morphology e.g. misshapen)
• Crusted skin is infested with hundreds of thousands / millions of mites
• Treatment:
  
  • Isolation
  • Topical Permetrhin + Oral Ivermectin