A common skin infection, scabies results from infestation with Sarcoptes scabiei var. hominis (itch mite), which provokes a sensitivity reaction. It’s transmitted through skin or sexual contact.
Mites can live their entire life cycles in the skin of humans, causing chronic infection. (The adult mite can survive without a human host for only 2 or 3 days.) The female mite burrows into the skin to lay her eggs, from which larvae emerge to copulate and then reburrow under the skin. (See Scabies: Cause and effect, page 1242.)
Scabies occurs worldwide, primarily in environments marked by overcrowding and poor hygiene, and can be endemic.
Typically, scabies causes itching, which intensifies at night. Characteristic lesions are usually excoriated and may appear as erythematous nodules. These threadlike lesions are approximately 1 cm long and generally occur between fingers, on flexor surfaces of the wrists, on elbows, in axillary folds, at the waistline, on nipples and buttocks in females, and on genitalia in males. In infants, the burrows (lesions) may appear on the head and neck.
Intense scratching can lead to severe excoriation and secondary bacterial infection. Itching may become generalized secondary to sensitization.
Generally, treatment for scabies consists of application of a pediculicide — permethrin, lindane cream, or crotamiton — in a thin layer over the entire skin surface from the neck down. Lindane and permethrin are left on the skin for 8 to 12 hours. Crotamiton is applied nightly for 2 consecutive nights and washed off 24 hours after the second application. To make certain that all areas have been treated, this application should be repeated in approximately 1 week.
Lindane is an effective scabicide and when used properly may be applied safely to children, but shouldn’t be used in children younger than age 2 or pregnant or nursing mothers because of potential neurologic toxicity. It also shouldn’t be applied immediately after a shower. A 6% to 10% solution of sulfur in petrolatum may be used if patients object to using lindane, but they should be advised that sulfur is messy and odorous.
Persistent pruritus (due to mite sensitization or contact dermatitis) may develop from repeated use of pediculicides rather than from continued infection. An antipruritic emollient, topical steroid, or oral antihistamine can reduce itching; intralesional steroids may resolve erythematous nodules.
❑ Instruct the patient to apply permethrin, crotamiton, or lindane cream or lotion from the neck down, covering his entire body. He must wait 15 minutes before dressing and avoid bathing for 8 to 12 hours or longer, depending on the treatment used. Contaminated clothing and linens must be washed in hot water or dry cleaned.
❑ Tell the patient not to apply lindane cream if his skin is raw or inflamed. Advise him that if skin irritation or hypersensitivity reaction develops, he should notify the physician immediately, discontinue using the drug, and thoroughly wash it off his skin.
❑ Suggest to the patient that his family members and other close personal be checked for possible symptoms.
❑ If a hospitalized patient has scabies, prevent transmission to other patients: Practice good hand-washing technique or wear gloves when touching the patient; observe wound and skin precautions for 24 hours after treatment with a pediculicide; gas autoclave blood pressure cuffs before using them on other patients; isolate linens until the patient is noninfectious; and thoroughly disinfect the patient’s room after discharge.
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Title: Professional Guide to Diseases (Eighth Edition)
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2005
ISBN: 1-58255-370-X
» Next page: Scabies (Handbook of Diseases)
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