Management

People  with  a  CD4  cell  count  over  200  cells/μL  usually respond  to  a single total body application of  topical  permethrin  (5%)  left on for 8 to 14 hours, and repeated after  1 week. If permethrin is not available, benzyl benzoate 25% emulsion for 24-36 hours. The lotion is usually applied once daily at night on 2 or 3 consecutive days. Sulphur 5-10% in cream or paraffin for 3 consecutive days and repeated in 1 week, may be another alternative option, particularly for neonates.[117][118]  Treatment also involves hot water washing and drying of clothing and linen harbouring the mite. The mite cannot survive longer than 4 days without epidermal contact. Skin lesions and pruritus usually resolve within 6 weeks, the time-frame given before treatment failure is diagnosed.[119]  After that time, re-evaluation of causes of persistent itch should be explored. They include cutaneous irritation secondary to over-treatment (this responds to topical steroids), contact dermatitis from scabicide, treatment failure from low compliance, resistance or relapse (possibly secondary to poor scalp treatment) or delusions.

Treatment failure may also be related to degree of immunosuppression and high mite burden. Repeated applications may be required, especially for patients with crusted scabies. Often, topical treatment does not penetrate the lesions of crusted scabies sufficiently for eradication. Therefore, keratolytic treatment with topical salicylic acid 5-10% or urea 40% can be given concomitantly.[120][121] In adults, systemic therapy of oral ivermectin 200 μg/kg in two doses 2 weeks apart can be given. However, topical permethrin has a faster onset of action in terms of itch control and reducing lesions count.[122]   Prophylactic treatment should be given for all household members and sexual contacts.[123]

Crusted scabies is highly contagious due to the massive number of mites released in the patient’s flakes to the surrounding environment, and the transmission via fomites is common for this type of scabies.[124]