From where does a tick acquire encephalitis? - briefly
Tick‑borne encephalitis virus is obtained by ticks during blood meals from infected small mammals, especially rodents such as the bank vole. The pathogen remains in the tick through its developmental stages, allowing transmission to later hosts.
From where does a tick acquire encephalitis? - in detail
Ticks become carriers of the encephalitis‑causing virus through the intake of infected blood from vertebrate hosts that serve as natural reservoirs. The principal reservoirs are small mammals such as rodents (e.g., bank voles, wood mice) and certain bird species that maintain viral circulation in endemic areas. When a larval or nymphal tick attaches to one of these hosts, the virus is ingested and replicates in the midgut epithelium, subsequently spreading to the salivary glands. This process enables transmission to the next host during subsequent feedings.
Key mechanisms of acquisition include:
- Transstadial maintenance: the virus persists as the tick develops from larva to nymph and from nymph to adult, ensuring continuity of infection across life stages.
- Co‑feeding transmission: adjacent ticks feeding simultaneously on the same host can exchange virus without the host developing a systemic infection, reinforcing local spread.
- Vertical transmission: infected females can pass the virus to their offspring, though this route contributes less to overall prevalence.
The most common vectors are members of the genus Ixodes, chiefly Ixodes ricinus in Central and Western Europe and Ixodes persulcatus in Eastern Europe and Siberia. These species inhabit forested and grassland habitats where reservoir hosts are abundant, creating a stable enzootic focus. Human infection occurs when an infected tick attaches and injects virus‑laden saliva during a blood meal.
Understanding the ecological link between reservoir hosts, tick vectors, and environmental conditions is essential for assessing risk areas and implementing preventive measures.