How to identify a tick with demodex? - briefly
Examine the specimen microscopically; demodex mites present as elongated, spindle‑shaped organisms attached to the tick’s cuticle. Identification is confirmed by the presence of characteristic chelicerae and dorsal striations.
How to identify a tick with demodex? - in detail
Identifying a tick that carries demodex mites requires a combination of visual inspection, microscopic examination, and, when necessary, molecular analysis. The process begins with the collection of the arthropod from the host or environment, followed by careful handling to preserve any associated microorganisms.
The external morphology of the tick provides initial clues. Focus on the following characteristics:
- Presence of fine, hair‑like structures on the dorsal surface, often mistaken for debris.
- Slightly increased translucency of the cuticle, especially in the ventral region.
- Abnormal coloration or mottling that deviates from typical species patterns.
After visual assessment, the specimen should be placed in a clearing solution (e.g., lactophenol) for a brief period to render internal structures visible. Subsequent slide preparation involves:
- Immobilizing the tick on a microscope slide with a drop of mounting medium.
- Gently pressing a coverslip to spread the cuticle without crushing delicate tissues.
- Examining under a compound microscope at 40–100 × magnification.
Key microscopic indicators of demodex infestation include:
- Elongated, worm‑like organisms situated within hair follicles or sebaceous glands of the tick’s integument.
- Characteristic “cigar‑shaped” bodies measuring 0.2–0.5 mm in length, with distinct anterior and posterior ends.
- Presence of two pairs of short legs near the anterior region, a hallmark of the genus «Demodex».
When morphological identification proves inconclusive, molecular techniques can confirm the presence of demodex DNA. Polymerase chain reaction (PCR) targeting the 18S rRNA gene, followed by sequencing, provides definitive species‑level identification. Sample preparation for PCR involves:
- Homogenizing a portion of the tick’s tissue in a lysis buffer.
- Extracting nucleic acids using a commercial kit or phenol‑chloroform method.
- Amplifying the target region with specific primers and analyzing the product via gel electrophoresis.
Combining these steps—visual cues, microscopic observation, and molecular confirmation—ensures accurate detection of demodex‑infested ticks and supports appropriate epidemiological or clinical responses.