Geographical distribution and prevalence of tick-borne encephalitis virus in questing Ixodes ricinus ticks and phylogeographic structure of the Ixodes ricinus vector in Norway.

The tick-borne encephalitis virus (TBEV), a zoonotic flaviviral infection, is endemic in large parts of Norway and Eurasia. Humans are mainly infected with TBEV via bites from infected ticks. In Norway, the main geographical distribution of ticks is along the Norwegian coastline from southeast (~59°N) and up to the southern parts of Nordland County (~65°N).

Distribution of Neoehrlichia mikurensis in Ixodes ricinus ticks along the coast of Norway: The western seaboard is a low-prevalence region.

Neoehrlichia mikurensis is a tick-borne pathogen widespread among ticks and rodents in Europe and Asia. A previous study on Ixodes ricinus ticks in Norway suggested that N. mikurensis was scarce or absent on the south-west coast of Norway, but abundant elsewhere.

Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks from three islands in north-western Norway.

Tick-borne encephalitis (TBE) is the most important viral tick-borne disease in Europe and can cause severe disease in humans. In Norway, human cases have been reported only from the southern coast. The aim of this study was to investigate the prevalence of tick-borne encephalitis virus (TBEV) in questing Ixodes ricinus ticks from the north-western part of Norway.