Besides climate change, what is helping ticks spread across Europe?

Details

Many factors shape the spread of the important tick vector Ixodes ricinus (Acari: Ixodidae) across latitudes and altitudes in Europe, as well as changes in its distribution within previously endemic areas. This evidence review draws on published literature and unpublished expert opinion from the VBORNET network to examine evidence for these changes in Europe and discuss climatic, ecological, landscape and human-related drivers.

The review groups the drivers into several types: factors directly related to climate change, contributing to geographic range expansion at altitudinal extremes in central Europe and latitudinal extremes in Scandinavia; changes in the distribution of tick hosts, particularly roe deer and other cervids; other ecological changes, such as habitat connectivity and changes in land management; and other human-induced changes. These factors are strongly interconnected and often not well quantified.

Although climate change plays an important role in certain geographic regions, non-climatic factors are becoming increasingly important across much of Europe. Landscape-scale habitat management and changes in the distribution and abundance of tick hosts are important considerations when assessing and managing the public health risks associated with ticks and tick-borne diseases in 21st-century Europe.

Better understanding and mapping of the spread of I. ricinus, including changes in its abundance, are essential for assessing the risk that infections transmitted by this vector species will spread. Enhanced tick surveillance using harmonized approaches would allow data comparisons and tracking of trends at EU level, improving communication about tick-borne disease risks to policy makers, other stakeholders and the general public.