In which regions are encephalitic ticks found? - briefly
Encephalitis‑transmitting ticks are found across temperate Eurasia (including Central and Eastern Europe, Russia, and parts of China), in the northeastern United States and southeastern Canada, and in regions of Africa and the Middle East where Hyalomma species occur. The main vectors are Ixodes ricinus, I. persulcatus, I. scapularis, and Hyalomma marginatum, each linked to its respective geographic zone.
In which regions are encephalitic ticks found? - in detail
Encephalitis‑transmitting ixodid ticks are concentrated in specific temperate and sub‑tropical zones where their vertebrate hosts thrive and climatic conditions support their life cycle.
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Western Europe – the principal vector, Ixodes ricinus, is widespread from the British Isles through Scandinavia to the Mediterranean foothills. Human cases of tick‑borne encephalitis (TBE) are reported in the United Kingdom, Germany, Austria, Switzerland, the Czech Republic, Poland and the Baltic states.
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Eastern Europe and the Baltic region – high‑incidence areas include Estonia, Latvia, Lithuania, Russia’s western districts, and the Czech‑Slovak border zone. Ixodes persulcatus predominates in forested and mixed‑wood habitats.
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Northern Asia – Siberian and Far‑Eastern Russian territories host I. persulcatus and I. pavlovskyi. Incidence peaks in the Ural Mountains, the Altai region, and the Primorsky Krai, extending into northern Kazakhstan and Mongolia.
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Central and Southern Asia – Haemaphysalis spp. and Dermacentor spp. act as vectors in the Himalayas, northern India, Pakistan, and parts of China (Heilongjiang, Jilin, Xinjiang). Tick‑borne encephalitis foci are documented in the Tibetan Plateau and the Korean Peninsula.
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Northern Africa and the Middle East – Hyalomma and Rhipicephalus ticks transmit viral encephalitis agents in Morocco, Algeria, Tunisia, Turkey, Iran and Iraq, especially in semi‑arid steppe and scrubland zones.
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North America – Ixodes scapularis and I. pacificus carry Powassan virus, a flavivirus causing encephalitis. Endemic zones cover the northeastern United States, the Great Lakes region, and the Pacific Northwest.
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Japan and the Korean archipelago – Ixodes ovatus and Haemaphysalis longicornis are associated with TBE‑like viruses in Hokkaido, Honshu and the Korean islands.
The distribution reflects the overlap of suitable climate (moderate temperature, high humidity), host availability (small mammals, birds), and vegetation (deciduous and mixed forests, grasslands). Surveillance data indicate expanding borders in several regions due to climate change and altered land use, leading to new foci in previously non‑endemic areas.