Parasitic skin infections
·Caused by Sarcoptes scabiei mite.
·Common at all ages.
·Diagnosis is not easy, so look closely for clues. Classically it causes itchy papular rash with visible burrows affecting finger and toe webs, palms, soles, wrists, groin, axillary folds, buttocks (truncal in infants). Excoriation, eczematization, urticaria, or impetigo may develop.
·Diagnosis is confirmed by microscopy of mite removed from burrow (rarely needed).
• Treat whole household and close contacts simultaneously with 12hr topical application below the head (in children <2yrs old all body except face) with permethrin cream (5%) or 24hr of malathion liquid (0.5%) washed off and then repeated the next day.
• Simultaneously, launder bed linen and underwear in a warm wash.
• Antihistamines or calamine lotion for itch, which may last for 10 days.
• Apply weak topical corticosteroid if scabies nodules are present.
·Infestation with Pediculus capitus (scalp ‘nits’), Pedicularis corporis (body), or Phthirus pubis (pubic area ‘crabs’).
• Common in all ages.
• Localized pruritis, s impetigo or regional lymphadenopathy.
• Lice are difficult to see, but small white eggs (nits) are easily seen attached to hair shafts.
• Treatment Daily thorough combing with fine-toothed comb combined with single shampoo with lotions of carbaryl (0.5%) or malathion (0.5%).
• Other insects Many biting insects (e.g. fleas, midges, bedbugs, mosquitoes) may cause erythematous macular lesions with central punctum or papular urticaria.
• Avoid bites, e.g. treat infested pets.
• Oral antihistamines.
• Topical steroids.
• Antibiotics if there is s bacterial infection.