From the Guidelines
Skin scrapings are a crucial diagnostic method for confirming scabies infestation, and an etiologic diagnosis should be attempted by light microscopic demonstration of mites, eggs, or mite feces on mineral oil preparation from several scrapings of typical scabies “burrows”. To perform this procedure, apply a drop of mineral oil to the suspected area, typically burrows found between fingers, on wrists, elbows, or genital areas. Gently scrape the skin with a #15 scalpel blade to collect material from the burrow, then transfer the sample to a microscope slide with another drop of oil and cover with a slip. Examination under low power microscopy can reveal Sarcoptes scabiei mites, eggs, or fecal pellets, confirming the diagnosis, as recommended by the practice guideline for evaluation of fever and infection in long-term care facilities 1.
Some key points to consider when performing skin scrapings for scabies include:
- The best sites to sample are fresh, non-excoriated burrows, particularly on the wrists, finger webs, and sides of fingers
- Characteristic burrows appear as thin, grayish, thread-like lines about 2-10mm long
- If proper diagnostic equipment is not available and clinical experience with scabies is limited, consider consultation with a dermatologist to inspect or obtain scrapings from suspected persons, as suggested by the guideline 1
- If scabies is confirmed, treatment typically involves permethrin 5% cream or oral ivermectin, and all household members and close contacts should be treated simultaneously to prevent reinfestation.
It is essential to note that the diagnosis of scabies should be based on the demonstration of mites, eggs, or mite feces on mineral oil preparation from several scrapings of typical scabies “burrows”, as stated in the guideline 1.
From the Research
Skin Scrapings for Scabies Diagnosis
- Skin scrapings are a diagnostic method used to confirm scabies infection by identifying the presence of Sarcoptes scabiei mites, eggs, or scybala in the skin 2, 3.
- The laboratory diagnosis of scabies using skin scrapings can be challenging, and the method has a sensitivity of 42.9% compared to standard superficial skin biopsy (SSSB) which has a sensitivity of 57.1% 3.
- Skin scrapings are often used in combination with other diagnostic methods such as dermoscopy, microscopy, and histopathology to confirm the diagnosis of scabies 2, 4.
Comparison with Other Diagnostic Methods
- A study comparing skin scraping and SSSB found that SSSB is an inexpensive and easy-to-apply method with high sensitivity for obtaining skin samples for scabies laboratory diagnosis 3.
- Dermoscopy is also a useful diagnostic tool for scabies, allowing for the visualization of burrows and mites in the skin 2, 5.
- Microscopy and histopathology are also used to diagnose scabies, but these methods require specialized equipment and expertise 4.
Clinical Context and Treatment
- The diagnosis of scabies should be confirmed by laboratory tests such as skin scrapings or other methods before starting treatment 2, 5.
- Treatment of scabies typically involves the use of topical or oral medications such as permethrin, ivermectin, or crotamiton, and may require repeated applications or doses 2, 5, 6.
- It is essential to treat all close contacts simultaneously with the source patient to prevent the spread of the infection 2, 5.