Many factors are involved in the latitudinal and altitudinal spread of Ixodes ricinus as well as in changes in the distribution within its known endemic zones. The drivers can be divided into those directly related to climatic change, those related to changes in the distribution of tick hosts or other ecological changes and anthropogenic induced changes. These factors are strongly interlinked and often not well understood or quantified. Better understanding and mapping of the spread of Ixodes ricinus is however essential to assess the risk of the spread of diseases transmitted by this vector species. Enhanced tick surveillance with harmonized approaches for comparison of data enabling the follow-up of trends at EU level will improve the messages on risk related to tick-borne diseases to policy makers, other stake holders and to the general public. (Texte intégral)