Ito et al.
Spatial distribution of ticks and tick-borne pathogens in central Hokkaido, Japan and associated ecological factors revealed by intensive short-term survey in 2024. PLoS One. 2026;21:e0349386. doi:10.1371/journal.pone.0349386.
Tick-borne pathogens associated with ixodid ticks are generally maintained in the field by ticks and wild animals and infect humans and domestic animals via tick bites, causing disease. Each tick-borne pathogen has its own vector species and preferential animal host species. The circulation of tick-borne pathogens is affected by environmental factors such as landscape, climate, and topography. The distribution of ticks, tick-borne pathogens, and environmental factors was examined in central Hokkaido, Japan.
In May and June 2024, a total of 9,908 ticks (4,608 adults and 5,300 nymphs) were collected by flagging at 171 sites in central Hokkaido around Sapporo. Nine species of adult ticks were identified: Ixodes ovatus, I. persulcatus, I. pavlovskyi, I. tanuki, Haemaphysalis megaspinosa, H. longicornis, H. flava, H. japonica, and H. concinna. A total of 9,745 ticks were pooled and analyzed for pathogens. Tick-borne encephalitis (TBE) virus, Yezo virus, Beiji nairovirus, Lyme disease group borreliae, and relapsing fever group borreliae were detected in the tick samples. TBE virus was detected in I. ovatus, I. persulcatus, and Haemaphysalis spp.
The predicted suitable habitats differed among pathogen and vector species. Among the environmental variables considered for modeling, snow depth appeared to contribute significantly to the differences in distribution among tick species and their associated pathogens.
The authors suggested that I. persulcatus is an important vector for the transmission of tick-borne pathogens to humans in this region. However, a higher proportion of I. ovatus ticks was infected with TBE virus. Therefore, I. ovatus should also be carefully monitored to help prevent disease occurrence and further spread of these pathogens.