Rising Tick-Borne Encephalitis Cases Highlight Growing Health Risk in Sweden

Sweden has seen a significant increase in tick-borne encephalitis (TBE) cases, with 504 reported in 2025 compared to 384 in 2024, according to the Folkhälsomyndigheten. This marks a troubling trend as TBE cases have more than doubled since 2014 when only 178 cases were recorded, and the country experienced a record 596 cases in 2023. Notably, 2025 saw the first occurrence of TBE cases every month of the year, signaling an extended tick activity season and a wider geographic spread of the virus.

The highest risk areas remain in Götaland and southern Svealand, including counties such as Stockholm and Värmland. A recent survey revealed that 26% of Swedes reported experiencing at least one tick bite in the past year. Although half of the population has received at least one dose of the TBE vaccine, only about 50% are following the complete vaccination schedule, which includes three initial doses followed by regular boosters. Katherina Zakikhany-Gilg, senior medical advisor at Pfizer, stressed the importance of completing the vaccination regimen for adequate protection against TBE, which can cause severe complications like encephalitis.

Climate change has contributed to the northerly expansion of tick populations in Sweden. The Swedish National Veterinary Institute (Statens veterinärmedicinska anstalt, SVA) conducted research collecting approximately 1,500 ticks between 2018 and 2019 to screen for 48 different pathogens, including various Borrelia bacteria species responsible for Lyme disease. These findings are essential for updating risk maps, indicating that new areas, particularly in northern Sweden, are facing emerging tick-borne disease risks.

With vaccination being the most effective preventive measure and a growing population at risk due to climate-driven tick expansion, public health officials emphasize increased awareness and adherence to vaccination recommendations. The extended tick season and wider distribution of infected ticks underline the urgent need for comprehensive strategies to manage and mitigate the risks of tick-borne diseases in Sweden.