DESCRIPTION
Intensely pruritic contagious infestation caused by Sarcoptes scabiei var. hominis mite.

HISTORY

• Patients complain of unremitting itching, cannot stop scratching.
• Uncommon for scabies to present in just one family member. Other members, especially   bed   partners,   also   symptomatic.
• Nodular lesions longest to heal.
• Crusted scabies (thousands of mites) may be source of epidemic scabies, seen in institutionalized patients.
• Persistent itching after adequate treatment due to a prolonged allergic response, presence of residual fecal matter.

PHYSICAL FINDINGS

• Linear burrow is classic lesion. Burrow can be curved or S-shaped, slightly elevated. Inflamed vesicles and papules, 1-2 mm in size, also common features. May also present with scattered inflamed pustules,   papules,  and   even   larger  nodules.
• Individual lesions may be excoriated.
• Typical locations are wrists, web spaces of hands, sides of hands and feet, genital area, warm intertriginous regions, abdomen. In infants, scalp, palms, soles affected more often.
• Secondary lesions (most common) have eczematous reaction pattern or secondary impetigo.
• Unique, advanced clinical variant is crusted (Norwegian) scabies. Patients— usually those with dementia, Down syndrome, immunosuppression—experience thick crusting and eczematous dermatitis, especially on hands, feet. Burrows most likely found in finger webs, wrists, sides of hands and feet, penis, buttocks, scrotum, and palms and soles of infants.
• Can be mis­diagnosed as insect bites, eczema,  impetigo.
• Mites, eggs, feces can be identified in a scabies preparation.

TREATMENT

• Apply permethrin (Elimite, Acticin) or lindane (Kwell) to entire skin surface from neck down, including under fingernails and toenails, and in umbilicus. Wash off in 8-12 hours.
• Head and neck uncommonly affected, but if lesions need treatment, take care to avoid eyes, mouth.
• Wash all clothes, bedclothes at time of application. House fumigation, extermination unnecessary.
• Single dose of oral ivermectin (Stromectol, 6-mg scored tablet)
  (200 jug/kg) also safe and effective for most patients. Repeating dose 2 weeks later may provide higher cure rate.
• Topical steroids may be used to control pruritus and inflammation after treatment with scabicide. Can treat persistent nodular lesions with intralesional steroids.
• Can treat secondary bacterial infections with appropriate antibiotics.
• Even adequately treated scabies may continue to itch for days to weeks after treatment, and does
  not need to be retreated in all cases.