Spatial distribution of ticks and tick-borne pathogens in central Hokkaido, Japan and associated ecological factors revealed by intensive short-term survey in 2024

Tick-borne pathogens are transmitted by tick bites to cause infectious diseases in humans and domestic animals. To anticipate the occurrence of tick-borne diseases, it is required to understand high resolution distribution of infection risk and associated ecological factors. The aim of the present study is to reveal the spatial distribution of ticks and ticks infected with pathogens in central Hokkaido, Japan. Adult and nymphal ticks were collected with a constant effort at 171 sites from 13 May to 26 June 2024, followed by screening tick-borne pathogens. The potential suitable habitats of seven tick species and the endemic tick-borne pathogens in the study area (i.e. tick-borne encephalitis virus, Yezo virus, Beiji nairovirus, Lyme disease group borreliae, and relapsing fever group borreliae) were predicted using ecological niche modeling. Ixodes persulcatus and Ixodes ovatus were identified as the primary ticks to determine the distributions of all the pathogens. Besides, the predicted suitable habitats were specific to each pathogen/tick species. Among the environmental variables considered for modeling, snow depth appeared to significantly contribute to the distribution differences between ticks and pathogens. The findings of this study expand our understanding of the spatial risk distribution of tick-borne pathogen infections and its ecological context.