How to differentiate a tick from an encephalitic one? - briefly
A tick that carries an encephalitis virus cannot be identified by visual characteristics; laboratory testing such as PCR or virus isolation is required. The presence of fever, headache, and neurological signs in the host after a bite indicates encephalitic infection rather than a harmless attachment.
How to differentiate a tick from an encephalitic one? - in detail
Ticks are small, eight‑legged ectoparasites that attach to the skin of mammals, birds, and reptiles. An encephalitis‑carrying tick is a specimen infected with a virus capable of causing inflammation of the brain. Differentiation relies on visual inspection, ecological data, and laboratory confirmation.
Visual inspection focuses on size, coloration, and anatomical details. Typical characteristics of a non‑infected tick include:
- Body length 2–5 mm (larvae) or 5–10 mm (nymphs and adults); enlargement after engorgement may reach 10–20 mm.
- Uniform brown, reddish‑brown, or black coloration; dorsal scutum distinct in males, absent in females.
- Presence of a rectangular or oval capitulum with palps and chelicerae visible under magnification.
Encephalitis‑associated specimens do not differ morphologically from uninfected ticks of the same species; the virus resides in the salivary glands and does not alter external appearance. Consequently, visual cues alone cannot confirm infection status.
Ecological and temporal factors provide indirect clues. Species known to transmit tick‑borne encephalitis (TBE) include Ixodes ricinus, Ixodes persulcatus, and Dermacentor reticulatus. Relevant considerations:
- Geographic distribution: forested, humid regions of Europe and Asia where TBE is endemic.
- Seasonal activity: peak questing activity in spring and early summer; nymphs most active May–June, adults June–July.
- Host preference: small mammals (rodents) serve as reservoirs; frequent attachment to humans during outdoor activities.
Laboratory testing offers definitive discrimination. Recommended procedures:
- Collect the attached tick with sterile tweezers, avoiding crushing the specimen.
- Preserve in 70 % ethanol or RNAlater for molecular analysis.
- Perform reverse transcription polymerase chain reaction (RT‑PCR) targeting the flavivirus envelope gene to detect TBE viral RNA.
- Confirm positive results with sequencing or immunofluorescence assay for viral antigens.
In practice, identification of the tick species combined with knowledge of regional TBE prevalence guides risk assessment. Definitive determination of viral infection requires molecular or serological testing of the specimen.