Epidemiological characteristics of natural focus and vector borne infectious diseases in Zibo City Shandong Province between 2004 and 2015

Objective To analyze the incidence trends and epidemiological characteristics of natural focus and vector borne infectious diseases in Zibo City between 2004 and 2015, and to provide evidence for control and prevention of the diseases. Method Surveillance data of natural focus and vector borne infectious diseases in Zibo City between 2004 and 2015 from "the National Disease Reporting Information System" were analyzed via descriptive epidemiological methods. Results A total of 10 natural foci and vector borne infectious diseases and 3 287 cases including 55 death cases were reported in Zibo City from 2004 to 2015. The average annual incidence was 6.24/100 000 and the case fatality rate was 1.67% (55/3 287). The incidence rate increased in recent years after the lowest rate in 2009 (2.83/100 000), and the rate in 2015 was 8.83/100 000. The top three diseases with higher incidence were hemorrhagic fever with renal syndrome (3.44/100 000), brucellosis (1.48/100 000) and tsutsugamushi fever (0.53/100 000). The top three high-prevalence areas with higher incidence were Yiyuan County (13.22/100 000), Zichuan District (9.73/100 000) and Boshan District (6.13/100 000). The cases mainly occurred from March to May and September, October, which accounting for 27.47% (903/3 287) and 24.64% (810/3 287), respectively of the total. The 40-59 year-old age group was the highest, accounting for 48.13% (1 582/3 287) of the total. And 75.48% (2 481/3 287) of reported cases were farmers. Conclusions The overall incidence of the natural focus and vector borne infectious diseases in Zibo City has a annual increasing trend in recent years, while the incidence of brucellosis and tsutsugamushi fever have continued to rise since 2004. These diseases have showed a significant seasonal distribution and population distribution. It is necessary to conduct targeted prevention and control strategies. Key words: Natural focus diseases; Vector borne infectious diseases; Epidemic characteristics