From the Guidelines
Diagnosing scabies requires a combination of clinical evaluation and microscopic confirmation, with the definitive diagnosis involving scraping the skin at the site of a burrow and examining the sample under a microscope to identify the Sarcoptes scabiei mite, its eggs, or feces 1. To diagnose scabies, a healthcare provider will first examine the skin for characteristic signs, including:
- Intense itching (especially at night)
- A rash with small red bumps or blisters
- Specific patterns of skin lesions in areas like finger webs, wrists, elbows, armpits, belt line, buttocks, and genitals The clinical presentation of scabies infection can be atypical, especially in debilitated patients, who may present only with hyperkeratosis, papules, or vesicles 1.
Diagnostic Approach
The diagnostic approach for scabies involves:
- Clinical evaluation: examining the skin for characteristic signs of scabies
- Microscopic confirmation: scraping the skin at the site of a burrow and examining the sample under a microscope to identify the Sarcoptes scabiei mite, its eggs, or feces
- Dermatoscopy: examining the skin with a special magnifying tool to reveal the mite or its burrows without needing a skin scraping
- Therapeutic trial: using anti-scabies medication and monitoring for improvement to support the diagnosis It's essential to note that scabies is highly contagious, so close contacts should be examined and potentially treated simultaneously to prevent reinfestation 1.
Considerations
In cases where the clinical presentation is highly suggestive but microscopic confirmation isn't possible, a therapeutic trial with anti-scabies medication may be used, and improvement after treatment supports the diagnosis 1. The intense itching of scabies results from a delayed hypersensitivity reaction to the mites, their eggs, and waste products, which is why symptoms can persist for several weeks even after successful treatment 1.
From the Research
Diagnosis of Scabies
To diagnose scabies, the following methods can be used:
- Microscopic demonstration of scabies mites 2
- Dermatoscopic demonstration of scabies mites 2
- Identification of thread-like papules (burrows) on the skin 2
- Presence of new, intense pruritus and dermatitis 2
Clinical Presentation
The clinical presentation of scabies includes:
- Papular rash at typical sites of predilection 3
- Severe itch at typical sites of predilection 3
- Burrows into the skin, producing a papular rash and severe itch 3
Diagnostic Considerations
When diagnosing scabies, the following should be considered:
- Scabies is a contagious infestation transmitted by skin-to-skin contact and sometimes by contact with contaminated material 3
- Scabies can be misdiagnosed or underdiagnosed due to its similarity to other skin conditions 2
- A thorough medical history and physical examination are essential for an accurate diagnosis 2
Laboratory Tests
Laboratory tests can be used to confirm the diagnosis of scabies, including: