Taiga tick species carrying severe disease found in Norway but not yet established

A tick species capable of transmitting more severe forms of tick-borne encephalitis (TBE) was detected in Norway in 2023 but has not yet established a permanent population, according to the Norwegian Institute of Public Health (FHI).

The Ixodes persulcatus tick, also known as the taiga tick, was first identified in Norway in 2023 during a study published in Science Direct. Researchers found four specimens—one female, two males, and one nymph—among 62 ticks collected near Brønnøysund in Nordland county. Unlike Norway’s common wood tick, the taiga tick can carry Siberian and Far Eastern TBE virus variants, which cause more severe illness than the European strain currently present in Norway.

Senior researcher Åshild Andreassen of FHI told Dagbladet that no further taiga ticks have been found in the same areas in 2024 or 2025. “We don’t believe there is an established population in Norway yet, but we are closely monitoring northern regions to detect any potential spread,” she said. The taiga tick has already established populations in Finland and Sweden.

TBE typically progresses in two phases: initial flu-like symptoms, followed by a fever-free interval before roughly 30% of patients develop encephalitis. The European TBE strain has a fatality rate below 1% in Western Europe. Existing TBE vaccines are effective against all three virus variants.

Andreassen advised heightened vigilance in the Brønnøysund area, where the milder climate may favor tick survival. FHI recommends protective clothing, insect repellent, and thorough body checks after outdoor activities to reduce tick exposure.