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.

  • Because the incubation period of the scabies mites is 3 weeks and the itch of scabies may take up to 8 weeks to develop, people may be infested but symptomless.

The efficacy and safety of scabicidal agents are difficult to determine due to limited trial data.

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.
In the past, topical treatment was applied after a hot bath. This is not necessary and there is even evidence that a hot bath may increase absorption into the blood, removing treatment from its site of action on the skin.
  • The treatment should be applied to cool, dry skin immediately before bedtime and allowing time for the cream to be absorbed or the lotion to dry.
  • Because the hands are likely to be affected by scabies, it is important not to wash the hands after application of the treatment and to reapply the preparation if the hands are washed within the treatment period.

NOTE: Permethrin 1% is not appropriate for scabies.



Counselling 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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