Analysis of epidemiological characteristics of four natural-focal diseases in Shandong Province, China in 2009-2017: A descriptive analysis

Natural-focal diseases are serious diseases that endanger human health. They threaten about 100 million people in Shandong Province, and cause illness in thousands of people each year. However, information on the epidemiological characteristics of natural-focal diseases in Shandong Province has been limited. The purpose of the study was to describe and analyze the epidemiological characteristics of natural-focal diseases in Shandong Province, 2009-2017. We describe the incidence and distribution of four natural-focal diseases in Shandong Province using surveillance data from 2009-2017. From 2009-2017, 11123 cases of four natural-focal diseases including 257 deaths were reported in Shandong Province, China. The four natural-focal diseases were severe fever with thrombocytopenia syndrome (SFTS), human granulocytic anaplasmosis (HGA), typhus, and scrub typhus. The high-risk groups of the four diseases were farmers and the elderly. The incidence rate of scrub typhus was significantly higher in females. However, this difference was not seen in the other three diseases. The four diseases were mainly clustered in the middle-southern part of Shandong Province and the Shandong Peninsula. The annual incidence of SFTS and scrub typhus increased, typhus was relatively stable, and HGA declined. However, the range of SFTS expanded, while HGA shrunk, and typhus and scrub typhus were unchanged. The epidemic period of SFTS and HGA was from May to October, typhus was from October to November, and scrub typhus was from September to November. The fatality rates of SFTS, typhus, scrub typhus, and HGA were 9.19%, 0%, 0.01%, and 2.24%, respectively. Our study described and analyzed the prevalence of natural-focal diseases in Shandong Province, and confirmed that age was closely related to the SFTS fatality rate. This study may help to improve the understanding of the prevalence of natural-focal diseases in Shandong Province in recent years and to better develop accurate prevention and control strategies for natural-focal diseases.