Study on tick fauna and factors causing SFTS patients in Fukuoka Prefecture, Japan

: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne diseases caused by the SFTS virus (SFTSV). In recent years, with the expansion of wildlife habitat, the chances of ticks invading a human living area have increased, accompanied by an increased risk of SFTSV infection. Here, we investigated the tick fauna and distribution of SFTSV in Fukuoka Prefecture and analyzed the factors associated with the occurrence of SFTS. A total of 1307 ticks were collected by flagging on vegetation between March and November during the study period from May 2017 to August 2019. Using cluster analysis based on the proportion of tick species at the collection points, we roughly classified the tick fauna in the prefecture into three clusters (Clusters 1 ‒ 3). The proportion of Haemaphysalis longicornis was extremely high in Cluster 1, and we detected SFTSV in one of the samples. We identified patients in the area of Cluster 1 ̶ the habitat of deer ̶ the main host of ticks, which was geographically consistent with the area of Cluster 1. These results suggest that deer habitat, with its high population density of H. longicornis , is implicated in the cluster of patients occurring in Cluster 1 area in with