Scabies

Aim

To guide PCH ED staff with the assessment and management of scabies.

Definition

Scabies is a skin condition resulting from the infestation of Sarcoptes scabiei scabies mites. 

Assessment⁶

• Diagnosis is usually clinical
• The clinical picture of pruritus and primary lesions (burrows, papules, vesicles and pustules) develops at 4-6 weeks after first infestation but within days of subsequent infestations. 
• Burrows (long tracks) are not commonly seen in children
• Pruritus is worse at night, and may manifest as irritability in infants
• Distribution:
  • Facial involvement is uncommon
  • Infants – usually palms, soles, axillae and scalp.  Can involve the entire body.
  • Children - usually involve web spaces of fingers and toes, flexor surfaces of arms / wrists / axillae and waistline
• Persistent lesions at 1 month after treatment suggest reinfection or persistent infection
• Secondary excoriation and bacterial infection is frequent
• Lichenification may occur with chronic infection.

Management

Permethrin 5%⁶

• Mainstay of treatment is topical anti-parasitic (permethrin 5% cream) applied to the entire body surface (see box) and left on for at least 8 hours. 
• A second treatment with permethrin 5% should be repeated 1 week after initial treatment.
• Treatment failure is relatively common and may be due to incompletely applied topical therapy, failure of contacts to be treated or non-compliance.
• Contact Infectious Diseases Consultant to discuss treatment in infants less than 2 months old. 
• Asymptomatic household members and close contacts (babysitters, grandparents) should be treated at the same time. *Note that PCH pharmacy will fill scripts for contacts of paediatric patients.

Application⁴

Adults and children > 2 years: apply the cream to the whole body but not the face and neck.

Infants and children < 2 years: apply the cream to the whole body including the neck, face, ears and scalp (avoid the area around the mouth and eyes, hands may be covered to avoid the cream being sucked off)

• Apply the cream to clean, dry and cool skin paying careful attention to web spaces of fingers and toes, soles of feet, under nails, body creases, armpits, genitals, buttocks, joints and joint creases.
• Apply to entire body surface, not just the lesions.
• Cream disappears when rubbed gently into skin.
• Reapply to hands if washed within 8 hours of application.
• Rinse after 8-14 hours with warm soapy water.
• Repeat application to whole body again after 7 days.
• Most lesions clear after a single application, but second treatment still needed.
• May cause a mild, transient stinging sensation.

Amount⁴

• 6-12 months up to 1/8 30g tube
• 1-5 years up to 1⁄4 30g tube
• 5-12 years up to 1⁄2 30g tube
• Adults and children >12 years apply up to one 30g tube (adults may occasionally require an additional tube, but do not apply more than 2 x 30g tubes)

Safety

• Safe for use in pregnancy⁵
• Australian product information recommends use in infants 6 months or older, however, the equivalent US information confirms both safety and efficacy in infants 2 months of age and older. Safety and efficacy below this age is not established. Discuss with Infectious Diseases team if scabies is diagnosed in children under 2 months age.

Further management⁶

• Pruritus frequently takes one week or longer to resolve after treatment.
  • Calamine lotion (available without prescription) may be indicated to control itch until symptoms resolve.
  • Antihistamines may help to control itching
• Look for and provide treatment of secondary bacterial infection (impetigo): Mupirocin 2% ointment can be used to treat a small number (<3) of localised lesions or refer to the Skin and Soft Tissue Infections - ChAMP guideline if oral antibiotics are required for extensive infection.
• Bed linen and clothing should be washed in hot water and sun dried.
• For items where this is not possible, they should be ironed or stored in a sealed plastic bag for 72 hours.

Nursing

• Contact precautions - gloves and long sleeve gowns.
• Place all linen in a plastic bag and then into the usual laundry bag.

References

1. National Healthy Skin Guideline: national-healthy-skin-guideline---1st-ed.-2018.pdf (thekids.org.au)
2. Australian Medication Handbook Children's Dosing Companion, Australian Medicines Handbook Pty Ltd, 2021. Mupirocin. Modified July 2021. Cited 4 November 2021. Available from: Mupirocin - AMH Children's Dosing Companion (health.wa.gov.au)
3. Australian Medication Handbook Children's Dosing Companion, Australian Medicines Handbook Pty Ltd, 2021. Permethrin. Modified July 2021. Cited 4 November 2021. Available from: Permethrin - AMH Children's Dosing Companion (health.wa.gov.au)
4. Lyclear® patient information leaflet, Johnson & Johnson Pacific Pty Limited.
5. Rossi S, Pharmaceutical Society of Australia, Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists, Royal Australian College of General Practitioners. Australian Medicines Handbook 2021. Available from: https://amhonline-amh-net-au.pklibresources.health.wa.gov.au/chapters/dermatological-drugs/scabicides-pediculicides/permethrin
6. Chandler DJ & Fuller LC, A Review of Scabies: An Infestation More than Skin Deep. Dermatology 2019;235:79–90

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