| ObjectiveTo understand the epidemiological characteristics of tsutsugamushi disease in Guangzhou,to explore the risk factors closely related to the disease,and to clarify the main epidemic genotypes of tsutsugamushi disease in the Oriental tsutsugamushi and the evolutionary relationship with surrounding areas and countries,so as to provide scientific basis for the prevention and control of disease and the evolution of Oriental tsutsugamushi.MethodsFrom January 1,2015 to December 31,2016,blood samples,eschars,rat blood and organs,chigger mites and other specimens of patients with tsutsugamushi disease were collected in Guangzhou.The epidemiological characteristics of tsutsugamushi disease in Guangzhou were analyzed by descriptive analysis,and the potential risk factors were discussed by case-control study.The seasonal characteristics were analyzed by using the method of circular distribution and concentration.Descriptive statistical method was used to analyze the distribution characteristics of main genotypes and the population structure of rodents,and maximum likelihood method was used to construct the phylogenetic tree for homology analysis.Statistical software used include RStudio 1.0.1,SPSS 20.0,EpiData 3.1,Sequencher 5.1,BioEdit 7.0.9,MEGA 5.0,etc.Results1.A total of 1105 questionnaires were collected,including 646 cases and 459 control.The age group with the most cases was 60~69,followed by 50~59.Among the occupational distribution,farmers account for the highest 59.28%,followed by domestic workers or unemployed.Primary school accounts for 36.69%,followed by junior high school 25.23%.The risk factors of tsutsugamushi disease in Guangzhou include: travel history(OR = 2.889,95% CI: 1.842-4.351),sitting and lying ongrassland(OR = 3.247,95% CI: 1.502-7.042),overgrowth of weeds(OR = 2.092,95% CI: 1.290-3.390),stacking of weeds or crops(OR = 1.959,95% CI: 1.246-3.080),and rat activity.2.The incidence of tsutsugamushi disease in Guangzhou has certain seasonal characteristics.The peak day is August 1,and the peak period is from May 25 to October 8 every year.3.The incidence of tsutsugamushi disease in districts in Guangzhou is unbalanced.In the central urban areas,such as Tianhe,Yuexiu,Huangpu and Liwan,the number of cases is less than 30.The district with more cases were mainly in the surrounding areas,such as Conghua,Panyu and Zengcheng,the number of cases was over 100.Conclusion4.A total of 646 cases blood samples and 600 rat blood samples were collected during the study period.154 cases blood samples were positive for scrub typhus,with a positive rate of 23.84%.The detected types were 99 strains of Karp,30 strains of Gilliam,16 strains of Kato and 9 strains of TA763,accounting for 64.29%,19.48%,10.39% and 5.84%,respectively.Nine rat blood samples were positive,with a positive rate of 1.50%.The detected types were 1 TA763,2 Kato,3 Karp and 3 Gilliam,respectively.Karp were the main endemic strains in Guangzhou,and the distribution of genotypes in different regions was uneven.5.The Oriental tsutsugamushi type in Guangzhou is closely related to Taiwan,Thailand,New Guinea,Japan,Malaysia,etc.6.A total of 1215 rodents were captured in rural and urban areas,covering 6species.Rattus noricus was the dominant species,with a total of 959 species,accounting for 78.93%.Conclusion1.The risk factors of tsutsugamushi disease in Guangzhou include traveling,sitting and lying on grass,weeds on the ground of the house,stacking of weeds or crops in the house,and rat activity in the community.2.Guangzhou is a natural epidemic focus of scrub typhus,and the peak is from May to November every year.3.The incidence of tsutsugamushi disease in Guangzhou is unbalanced,with the majority in the surrounding areas.4.The epidemic strains of tsutsugamushi disease in Guangzhou showed diversity,mainly type are Karp,Gilliam,Kato and TA763.5.Homologous analysis showed that the Oriental tsutsugamushi in Guangzhou was closely related to Taiwan province,Japan,Thailand,Korea and Malaysia. |
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