Climate change influences on the potential geographic distribution of Ixodes ricinus, vector of Lyme borreliosis and tick-borne encephalitis virus

Abstract

Abstract Background: Ixodes ricinus is a hard tick vector species that transmits many diseases in Europe and North Africa, including borreliosis (Lyme disease) and tick borne encephalitis (TBE). Climate change has altered distributions and transmission patterns of many vectors and vector-borne diseases, but such effects on I. ricinus have received little attention. In this study, we assessed the potential distribution of I. ricinus under both current and future climate conditions to understand possible changes in pathogen transmission patterns in coming decades. Method: We integrated occurrence datasets and relevant environmental variables to generate ecological niche models to estimate the current distribution of I. ricinus with respect to climate, and then assessed its future potential distribution under different climate change scenarios. Future projections were based on 17 general circulation models (GCMs) and 2 representative concentration pathways (RCPs), for 2050 and 2070. Result: The present potential distribution of the species showed broad agreement with future distributional predictions, including most of western and central Europe, a narrow zone in eastern and northern Europe, and a narrow fringe of North Africa. Potential expansions were observed in northern and Eastern Europe. These results indicate that I. ricinus could emerge in presently non-endemic areas, posing increasing risks to human health in these areas. Keywords: Climate change, ecological niche modeling, Maxent, future projection, Lyme disease, tick-borne encephalitis, Europe, North Africa, Middle East.