How can a skin mite be identified? - briefly
Identification is achieved by examining skin scrapings under a microscope, where the mite’s oval body and eight legs are visible. Confirmation can be obtained with dermatoscopic observation of burrows or molecular assays detecting mite DNA.
How can a skin mite be identified? - in detail
Skin mites are diagnosed through a systematic approach that combines clinical observation, specimen collection, and laboratory analysis. The process begins with a thorough patient history and visual examination of lesions. Typical signs include intense itching, erythema, papules, vesicles, or burrows that follow the mite’s movement pattern. Distribution often involves the webs of the fingers, wrists, elbows, or the genital region, depending on the species.
Specimen collection
- Skin scrapings: Gently scrape the affected area with a sterile blade, collecting material from the active border of a lesion. Use a clean slide for transport.
- Tape impressions: Apply clear adhesive tape to the skin, press gently, then transfer the tape onto a microscope slide. Effective for detecting mites in superficial layers.
- Dermoscopy: Employ a handheld dermatoscope to visualize live mites and their tracks without invasive sampling.
Microscopic examination
- Light microscopy at 10–40× magnification reveals whole mites, eggs, and fecal pellets. Identify key morphological traits:
- Body shape: elongated, oval, with a dorsal shield.
- Leg count: four pairs of short legs on the anterior half.
- Gnathosoma: mouthparts positioned ventrally.
- Size: typically 0.2–0.4 mm, distinguishable from other ectoparasites.
- Phase-contrast or dark-field illumination enhances contrast, allowing observation of movement in fresh specimens.
- Staining (e.g., lactophenol cotton blue) clarifies internal structures for species-level identification.
Molecular techniques
- DNA extraction from collected material followed by polymerase chain reaction (PCR) targeting mitochondrial COI or 18S rRNA genes confirms species identity, especially in ambiguous cases.
- Real-time PCR provides quantitative data on mite load, useful for monitoring treatment efficacy.
Differential diagnosis
Compare findings with other dermatological conditions such as bacterial folliculitis, fungal infections, or allergic dermatitis. The presence of live mites or characteristic eggs differentiates mite infestation from these alternatives.
Interpretation and reporting
Document the number of mites per high-power field, note the developmental stage (adult, nymph, egg), and indicate any coexisting pathogens. Include recommendations for topical acaricides, oral antiparasitic agents, and environmental decontamination when appropriate.
By adhering to this structured protocol, clinicians can reliably detect and differentiate skin mites, ensuring accurate diagnosis and targeted therapy.