Diagnosis: Scabies
Scabies on a teenager's hand.. Clinical photograph sourced from Wikimedia Commons (CC BY-SA 4.0). Attribution: Gzzz.
Intensely pruritic papules, vesicles, and linear burrows in characteristic distribution: interdigital web spaces, wrists, elbows, axillae, periumbilical area, genitalia. Crusted (Norwegian) scabies in immunocompromised patients shows thick hyperkeratotic plaques.
Pruritus worse at night (mite activity increases with warmth). Close contacts often symptomatic. Institutional settings at higher risk. Symptoms develop 2-6 weeks after primary infestation, within 1-3 days with re-infestation.
First-line: permethrin 5% cream (apply neck-down, wash off 8-14 hours). Alternative: oral ivermectin (200 mcg/kg, repeat day 8-15). Treat all household contacts simultaneously. Launder bedding/clothing in hot water. Crusted scabies: combined topical + oral treatment.
Atopic dermatitis, Contact dermatitis, Dermatitis herpetiformis, Insect bites, Folliculitis, Prurigo nodularis
Mineral oil scraping of a burrow confirms diagnosis with mite, eggs, or scybala visualization. Post-scabetic itch can persist 2-4 weeks after successful treatment. Treat all contacts regardless of symptoms to prevent re-infestation.
Tags: scabies, infestation, parasitic, pruritic, mite