Scabies

Introduction

Scabies is an intensely itchy skin condition, especially at night, caused by the mite Sarcoptes scabiei. The diagnostic burrows are small (0.5-1.5 cm grey irregular tracks) and scratching often makes them difficult to see.

  • The mite is transmitted by direct physical contact (e.g. holding hands, hugging, or sexual contact), although transmission through casual contact like shaking hands is unlikely.
  • Occasionally, scabies is acquired via bedding or furnishings.

Scabies typically affects the finger webs, sides of the fingers and wrists.

  • In adults, it rarely affects the scalp and face, but in children aged 2 years or under and the elderly, the head is more common affected, especially the area behind the ear.

Scabies Scabies



Management

All household members and close contacts of the affected individual should be treated simultaneously, even in the absence of symptoms.

The efficacy and safety of scabicidal agents are difficult to determine due to limited trial data. Options include benzyl benzoate 10-25%, crotamiton, permethrin 5%, malathion 0.5% and 2-10% precipitated sulphur ointment, gamma benzene hexachloride 1% and oral ivermectin.

  • Permethrin 5% is the drug of choice for patients ≥2 months old due to its low toxicity and high efficacy and is generally well tolerated.
  • Oral ivermectin (not registered in Malaysia and off-label use for scabies) is another first-line recommended regimen, however only for patients weighing more than 15 kg.
  • Gamma benzene hexachloride (Lindane) has been associated with neurotoxicity concerns and classified as carcinogenic to humans. The use is banned in California, United Kingdom and Australia.
  • Malathion has been classified as probably carcinogenic to humans.

Topical treatments should be applied to the entire body, including the neck, face, scalp and ears in adults.

  • Particular attention should be paid to the webs of fingers, soles of the feet and under the ends of the fingernails and toenails.

NOTE: Permethrin 1% is not appropriate for scabies.



Counseling Points

The scabies mite can survive up to 36 hours off from human skin.

Soft toys, bed linen and clothing that has been in contact with the person in the previous 48-72 hours should be washed and dried on hot machine settings (at >60°C) the morning after each treatment.

  • Alternatively, store them in tightly sealed plastic bags for several days to a week (at least 3 days).

School leave or medical leave to patients for proper administration of medication should be given (as patients remains infectious 24 hours after application).

  • The school should be notified of the case, and parents of other children who may have been exposed to scabies should be notified by letter from the school.

The itch and eczema of scabies can persist for 2-4 weeks after completing treatment.

  • Further treatment of pruritus and eczema may be required (e.g. crotamiton cream, antihistamines, corticosteroids and emollients).
  • However, persistent symptoms suggest that scabies eradication was not successful.



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