Mathews-Martin et al.
Meteorological and environmental factors associated with the exposure to tick-borne encephalitis virus (TBEV) in cattle, north-eastern France, 2018–2019. Vet Res. 2025;56:157. doi:10.1186/s13567-025-01588-8
Most cases of tick-borne encephalitis (TBE) in France have so far been reported in the Alsace region, located in north-eastern France. More recently, an outbreak occurred in the Ain department (eastern France), involving 43 individuals who became infected after consuming cheese made from unpasteurized goat’s milk (see, e.g., Newsletter May 2022). Between May 2021 and May 2023, approximately 6.5% of autochthonous TBE virus infections in France were suspected to be foodborne.
These incidents have raised concerns about the potential for TBE transmission through alimentary routes in France. In response, a serological survey was conducted in the Alsace-Lorraine region to estimate the level of TBE virus exposure in cattle and to identify meteorological and landscape factors associated with this exposure.
The overall apparent seroprevalence, based on ELISA testing, was 7.5%, with 335 out of 4,483 cattle testing positive. The highest levels of exposure were observed in the eastern Vosges and western Haut-Rhin departments.
Cattle were more likely to be exposed to TBE virus in areas characterized by a mixed forest cover exceeding 28%, a mean annual daytime land surface temperature below 12°C, and a proportion of meadow adjacent to forest greater than 3.5%.
These findings indicate that the TBE virus is widely distributed across several departments in north-eastern France, including areas where no human cases have yet been reported. This suggests the possibility of under-diagnosed human infections and highlights the importance of more systematic testing in patients presenting with compatible symptoms.