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  • • Suspected Sarcoptes scabiei infestation; the diagnosis should be verified because it is often overdiagnosed.

  • • Glass microscope slide.

    • Mineral oil.

    • Cotton-tipped applicator.

    • Microscope.

    • #15 scalpel blade or other device to scrape skin.

  • • Minimal discomfort and bleeding with vigorous scraping.

  • • Scrape burrows or unexcoriated papules.

    • The highest yield of mites, eggs, or fecal pellets is from the burrows, which are most commonly found on hands or feet.

    • If many family members have lesions, perform the scraping on the parents, who are often more cooperative and less fearful than infants or young children.

    • Treatment includes eradication of the mites on the patient, treatment of associated problems (pruritus, scabietic nodules), treatment of personal contacts, and destruction of the mite in the patient’s surroundings.

  • • Parents and patients should be aware that scraping may cause minimal bleeding and mild discomfort.

  • • Patient should be positioned in good lighting with access to lesion to be tested.

  • • Drop mineral oil on to a sterile blade or the lesion itself with a cotton-tipped applicator.

    • Vigorously scrape the lesion 5–6 times until it is unroofed. This may produce bleeding.

    • Collect material from as many lesions as possible, preferably from burrows.

    • Transfer material from each lesion to the slide, add a few more drops of mineral oil, and cover with the coverslip (Figure 39–1).

Figure 39–1.

Scabies under the microscope.

  • • Scan slide on low-power objective.

    • Diagnosis is made by seeing the mite itself (0.2–0.4 mm in size), mite parts, eggs (oval and one-tenth the size of the mite), egg cases, or golden-brown fecal pellets (scybala).

    • Feces and eggs are easier to find than mites. Feces often occur in clumps.

    • Air bubbles (usually round) are an artifact that can be mistaken for eggs. Gently press on coverslip to dislodge these.

  • • If treated adequately, follow-up is not indicated.

    • Pruritus may persist for weeks or months in patients even after adequate therapy.

Cunningham BB, Wagner AM. Diagnostic and therapeutic procedures. In: Eichenfield LF, Frieden IJ, Esterly NB. Textbook of Neonatal Dermatology. Philadelphia: WB Saunders Company; 2001:77.
Rasmussen JE. Body lice, head lice, pubic lice and scabies. In: Arndt KA, LeBoit P, Robinson JK, Wintroub BU, eds. Cutaneous Medicine and Surgery. Philadelphia: WB Saunders Company; 1996:1195–1199.

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