How does an encephalitic tick bite? - briefly
A tick attaches to the skin, inserts its hypostome, and secretes saliva containing the encephalitis‑causing virus while feeding. Transmission occurs within minutes to hours as the virus moves from the tick’s salivary glands into the host’s bloodstream.
How does an encephalitic tick bite? - in detail
Ticks attach to the skin using their chelicerae and hypostome, which pierce the epidermis and anchor the arthropod. During the initial 24‑48 hours, the tick secretes saliva containing anticoagulants, immunomodulators, and enzymes that facilitate blood ingestion and suppress local host defenses. The encephalitis‑causing virus, typically the tick‑borne encephalitis (TBE) virus, resides in the tick’s salivary glands after replicating within the vector’s midgut following an earlier infectious blood meal.
Transmission occurs when the tick begins to ingest blood and injects saliva into the feeding site. The virus is released in minute quantities, mixing with the host’s interstitial fluid. Because the virus is present in the salivary glands, it can be transferred as soon as the tick’s feeding apparatus penetrates the dermis, but efficient infection usually requires a feeding duration of at least 48 hours. Shorter attachment periods often result in insufficient viral load to establish systemic infection.
Key steps in the process:
- Attachment: Chelicerae cut the skin; hypostome embeds, creating a secure channel.
- Saliva injection: Anticoagulant and immunosuppressive compounds are delivered, maintaining blood flow and reducing inflammation.
- Virus release: TBE virus particles emerge from the salivary glands and enter the host’s tissue.
- Replication phase: After entry, the virus replicates locally in skin cells and migrates to regional lymph nodes, eventually reaching the central nervous system.
Factors influencing transmission risk include:
- Tick species: Ixodes ricinus and Ixodes persulcatus are primary vectors in Europe and Asia.
- Feeding duration: Longer attachment increases viral dose.
- Host immune status: Immunocompromised individuals may acquire infection more readily.
- Seasonal activity: Tick activity peaks in spring and early autumn, correlating with higher incidence of encephalitic cases.
Preventive measures focus on early tick removal, proper clothing, and repellents, which interrupt the feeding cycle before the virus can be transmitted.