The region is a transitional region epidemic area, the transmission host is Rattus norvegiacus and Cricetulus triton, the transmission vector is Leptotrombidium scutellare.

• 90%25,疫区属过度地带疫源地,传播宿主为褐家鼠和大仓鼠,传播媒介为小板纤恙螨,小板纤恙螨的季节消长与发病时间一致。