| Objective:To understand the fecal contamination of definitive hosts of Echinococcus and analysis of the influencing factors in Seda County,Ganzi Prefecture,Sichuan Province,as well as the current situation of the prevention and control knowledge of echinococcosis among middle school students in Seda and Daofu Counties of Ganzi Prefecture,so as to provide reference for rational allocation of health resources,formulation of scientific and effective echinococcosis prevention and control strategies.Methods:In October 2020,the questionnaire survey was conducted among the dog owners distributed along the main traffic routes and field grazing routes in Seda County of Ganzi Prefecture.The basic information and deworming information of the domestic dogs were recorded,and the dog feces were collected.At the same time,a survey spot was selected every 1-2 km along the main traffic routes and field grazing routes in Seda County using the method of mechanical sampling.The geographic location of the survey spots,the number of feces,pasture type,terrain type,vegetation type,vegetation coverage,mean grass height,the density of rodents and lagomorphs and definitive hosts feces species were recorded.PCR was used to detect fecal Echinococcus infection.The cluster sampling method was adopted to select the students in the second year of all middle schools in Seda and Daofu Counties of Ganzi Prefecture to conduct a questionnaire survey,and statistics were made on the qualified rate and awareness rate of students about echinococcosis transmission,symptoms,treatment,prevention,harm and preferential policies adopted by the country.Chi-square test,Fisher’s exact probability test,Wilcoxon Two-sample test,Kruskal-Wallis H test,Bonferroni test and Nemenyi test were used to analyze the contamination and distribution characteristics of definitive hosts feces as well as the qualified rate and awareness rate of echinococcosis control knowledge among middle school students.Logistic regression model and Random Forest model were established to explore the influencing factors of fecal contamination of definitive hosts of Echinococcus in the field.Results:1.The Em prevalence of domestic dogs was 1.89%(1/53)in Seda County,Ganzi Prefecture,Sichuan province.There was no significant difference in the Em prevalence among domestic dogs of different genders,different ways of chained and whether to go to summer pasture(P>0.05).The distribution rate of definitive hosts feces and positive feces in survey spots were 85.00%(34/40)and 42.50%(17/40),respectively.The density of feces and positive feces in survey spots were 3.50/10000 m~2(1.00/10000 m~2-8.00/10000 m~2)and 0/10000 m~2(0/10000 m~2-1.00/10000 m~2),respectively.PCR results showed that the definitive hosts’ fecal positive rates of Echinococcus,Es and Em in field were 18.06%(41/227),14.10%(32/227)and 4.85%(11/227),respectively.Two fecal samples were mixed infected with Es and Em.The fecal positive rate of Es in winter pasture was(15.92%,32/201)higher than that in summer pasture(0,0/26)(P<0.05).The definitive hosts’ fecal density of alpine meadow(7.17/10000 m~2)was higher than that of alpine shrub meadow(3.44/10000 m~2)(P<0.05).For rodents and lagomorphs densities,the fecal density of rodents and lagomorphs with the density of 401-600/10000 m~2(12.25/10000 m~2)was higher than that of ≤200/10000 m~2(3.32/10000 m~2)(P=0.006);and the fecal positive rates of Es of rodents and lagomorphs with the density of ≥601/10000 m~2(29.73%,11/37)was higher than that of ≤200/10000 m~2(5.48%,4/73)(P<0.001).The fox fecal positive rate of Echinococcus and Es were 25.95%(34/131)and 22.14%(29/131),respectively,which were higher than that of dog feces(7.45%,7/94;3.19%,3/94)(P<0.001).There was no significant difference in the positive rate of Em between dog feces(5.32%,5/94)and fox feces(4.58%,6/131)(P>0.05).2.The results of multivariate Logistic regression analysis showed that the risk of positive fecal contamination of definitive hosts at the elevation of 3934-4033 m was 0.055 times higher than that at the elevation of ≥4034 m(OR=0.055,95%CI=0.006-0.478).The probability of positive fecal contamination of definitive hosts at the survey spot was increased by 1.167 times for 1 feces increase of definitive hosts.(OR=1.167,95%CI=1.006-1.353).3.The importance analysis of variables in the random forest model showed that the top 3 variables were elevation,number of feces and the density of Ochotona curzoniae.Partial Dependence Plots showed that the probability of positive fecal contamination of definitive hosts decreased with elevation to a minimum of 4000 m,and then increased to high probability;Within the range of feces collected at survey spots,the probability of positive fecal contamination of definitive hosts increased with the fecal quantity;Within the range of O.curzoniae density recorded at survey spots,the probability of positive fecal contamination of definitive hosts increased with the density of O.curzoniae on the whole.4.A total of 1087 questionnaires were assigned to investigate the prevention and control knowledge of echinococcosis among middle school students in Seda and Daofu Counties of Ganzi Prefecture,and 1033 valid questionnaires(95.03%)were collected.The total qualified rate of echinococcosis prevention and control knowledge was 85.87%,and the qualified rate of girls was higher than that of boys(χ~2=11.594,P<0.05).The qualified rate among students of different ages was statistically significant(P<0.05),and the qualified rate increased with age(χ~2 trend=31.691,P<0.01).There was significant difference in the qualified rate among different school students(χ~2=134.680,P<0.01).The total awareness rate of echinococcosis prevention and control knowledge among students was 75.60%,and the awareness rates of source of infection,route of transmission,susceptible groups,symptoms,treatment,prevention,harm and preferential policies adopted by the country were 63.70%,32.43%,81.90%,61.57%,71.73%,58.28%,28.56%and 20.72%,respectively.The total awareness rate of echinococcosis prevention and control knowledge of Daofu and Seda Middle School students was 78.95%and 68.44%,respectively,and the difference was statistically significant(χ~2=287.866,P<0.01).Conclusion:1.The fecal pollution of Echinococcus definitive hosts is serious in the field in Seda county,Ganzi Prefecture,Sichuan Province,fox is the main source of infection in the field,and the positive rate of Em is high in dog feces.The number of feces,elevation,winter pasture,alpine meadow and high density of rodents and lagomorphs are the main influencing factors for fecal contamination of Echinococcus definitive hosts in the field.It is suggested that this kind of area should be regarded as the key surveillance area for echinococcosis in the field.It is necessary not only to further strengthen the deworming and management of domestic dogs,but also to carry out deworming for wild canine animals.The results of this study are of great significance for the formulation of control strategies of echinococcosis sources of infection and the implementation of scientific and effective prevention and control measures in the Tibetan Plateau.2.The echinococcosis prevention and control knowledge among students in Seda and Daofu Counties of Ganzi Prefecture of Sichuan province is generally good,but there is still an epidemic risk of echinococcosis.It is still necessary to carry out targeted health education in combination with the regional reality and the characteristics of the students(boys,young age,etc.),especially focusing on the propaganda and interpretation of misunderstanding knowledge points and weak knowledge points. |
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