| Objective:Focusing on the scientific question,namely the mechanism of transmission behavior and corresponding intervention strategy of clonorchiasis in highly endemic areas in China,this study aimed to explore the transmission intensity,mechanism of transmission behavior and behavioral intervention strategy of clonorchiasis,which is expected to provide the theoretical evidences and practical approaches to control the transmission of clonorchiasis in China.Methods:This study included seven chapters grouped into three parts.Part 1:The epidemiological data of clonorchiasis between 2015 and 2017 in China were collected,based on which the number of persons examined and infected with Clonorchis sinensis at town level by genders and age groups was calculated.High resolution data for important variables were collected from open access resources.Based on the available data at town level,Bayesian geostatistical models were established,which included the selected variables and spatial random effects.Then,such parameters as median and 95%Bayesian credible intervals(95%BCI)were provided for prevalence and estimated population under infection at national and provincial levels.Chapter 1 in Part 2:Totally,17 counties were selected from four clonorchiasis high endemic provinces(namely Guangxi,Guangdong,Heilongjiang and Jilin)based on results from Part 1.About 1000 habitants were surveyed in each county,including the infection status with C.sinensis and practice in eating raw freshwater fish.The linear relationship between the proportion in eating raw freshwater fish and prevalence of clonorchiasis was analyzed by counties,genders and age groups,and the parameter of coefficient of determination(R2)was provided.Then,relative risk(RR)and 95%confidential intervals(95%CI)was calculated for those with raw-eating practice compared to those without the practice.Subsequently,attributable risk per cent(ARP)and population attributable risk per cent(PARP)was analyzed.Chapter 2 in Part 1:One high school with 6 classes,5 middle schools with 15 classes and 5 primary schools with 15 classes were selected from each of the 17 counties mentioned above.The knowledge on clonorchiasis,practice in eating raw freshwater fish,and belief not to eat in future in students,as well as their parents'raw-eating practice were collected through questionnaire.Students were classified into four groups,namely Group 0(neither parents eating),Group 1(only father eating),Group 2(only mother eating)and Group 3(both parents eating).Linear regression was applied to capture the changing trends of variables by ages.Univariate and multivariate logistic regression models were employed to capture the risk factors related to practice and belief of students,in which odds ratio(OR)was provided.Both binomial distribution and ?-binomial distribution were used to detect the familial aggregation in raw-eating practice.Clustering coefficient(?)was provided to demonstrate the aggregation degree,and linear regression was adopted to show the changing trends of? by students' ages,and paired t test was employed to compare ? in different genders by ages.The interaction between fathers'and mothers' practice in eating raw freshwater fish was also explored.Chapter 3 in Part 2:A decision tree model was employed to explore the mechanism which drives the belief not to eat raw freshwater fish in future,based on the data in Chapter 2.All the factors were enrolled including genders,ages,knowledge,raw-eating practice of the students,as well as their parents' raw-eating practice.Chapter 1 in Part 3:Experts' brainstorming and Delphi methods were used to establish the evaluation system for health education products on helminthiases including clonorchiasis.Health education products were collected around the country,which were then assessed through the established evaluation system.The characteristics of collected and awarded products were analyzed.Chapter 2 in Part 3:Because no products targeting clonorchiasis met the need for intervention,a cartoon product aiming to change the behavior of students was designed and produced.The key knowledge for control on clonorchiasis was extracted from Part 2 and literature review.Then,a story was conceived,and the script was developed integrating the key knowledge.A cartoon named "A changing life of live fluke" was finally produced based on the script.Chapter 3 in Part 3:A parallel control trial was implemented to verify the behavioral intervention strategy on transmission of clonorchiasis in primary school students.One school in high endemic area was set as intervention group,while another as control.In intervention group,diverse behavioral interventions were implemented,including demonstration of the cartoon,distribution of foldout and erection of board to show the knowledge on clonorchiasis.Then,a drawing competition in Grade 1-3 and writing competition in Grade 4-6 was carried out.By comparing the data between baseline and evaluation surveys and intervention and control groups,effectiveness of this behavioral intervention strategy was assessed through such indicators as knowledge,practice and belief.Results:Part 1:The median of national prevalence of clonorchiasis in China in 2015 was 0.84%(95%BCI:0.63%-1.14%)and an estimated number of 10.82 million(95%BCI:8.04 million-14.71 million)was infected.High prevalence was detected in Guangxi(9.85%,95%BCI:6.43%-16.15%),Guangdong(4.59%,95%BCI:3.19%-7.14%),Heilongjiang(1.73%,95%BCI:1.28%-2.62%)and Jilin(0.72%,95%BCI:0.57%-1.05%).The number under infection was 4.92 million in Guangdong,4.06 million in Guangxi,0.66 million in Heilongjiang and 0.20 million in Jilin.Chapter 1 in Part 2:A total of 16230 participants enrolled from 16 counties were included for analysis.The proportion in eating raw freshwater fish was 26.46%(4295)and prevalence of clonorchiasis was 10.76%(1747).There existed a positive linear trend between them by counties(R2=0.44,P<0.01).There existed positive linear trends between the proportion of raw-eating practice and prevalence by age groups in both genders(R2=0.96,P<0.01 in male and R2= 0.99,P<0.001 in female).Compared to those without raw-eating practice,the probability(RR)infected with C.sinensis in those with the practice reached 12.93(95%CI:11.36-14.72).The ARP was 92.27%and PARP was 75.95%.Chapter 2 in Part 2:Totally,23222 students aged 9-18 years old from 15 counties were eligible for analysis.The proportion of Group 0,Group 1,Group 2 and Group 3 was 68.59%,17.20%,1.32%and 12.88%,respectively.The percentage in raw-eating practice was higher in boys(19.77%)compared to that in girls(12.30%)(?2?241.15,P<0.001).Following the increase by ages,the proportion increased linearly.The proportion increased by 115.40%in girls and 145.86%in boys from 9 to 18 years old,namely a yearly increasing rate by 8.90%and 10.51%,respectively.Compared to Group 0,the adjusted OR in practice was 10.50(95%CI:9.40-11.72)in Group 1,33.58(95%CI:26.29-42.90)in Group 2 and 47.10(95%Cl:42.02-52.81)in Group 3.The percentage on the belief not to eat raw freshwater fish in future was 77.61%in boys and 86.18%in girls(?2=287.64,P<0.001).Increased by ages,the proportion declined linearly.From 9 to 18,the proportion decreased by 7.03%in girls and 15.75%in boys,with a yearly decreasing rate by 0.81%and 1.89%,respectively.Compared to Group 0,the adjusted OR in belief was 0.78(95%CI:0.71-0.86)in Group 1,0.67(95%CI:0.52-0.88)in Group 2 and 0.69(95%CI:0.62-0.78)in Group 3.The raw-eating practice met 0-binomial distribution(?2=0.76,P>0.05)other than binomial distribution(?2=19553.23,P<0.001).The 0 was 0.87,and increased by ages of students(R2=0.82,P<0.001).Overall,0 was higher in those families with boys compared to those with girls(t=-4.09,P<0.01).When fathers ate raw fish,the RR of mothers' raw-eating practice was 22.64(95%CI:20.03-25.59).The ARP was 95.58%and PARP was 86.69%.When mothers ate raw fish,the RR of fathers'eating was 4.52(95%CI:4.00-5.11).The ARP was 77.89%and PARP was 33.35%.Chapter 3 in Part 2:In the decision tree model,when students didn't eat raw freshwater fish,they would have the belief not to do in future.When the attributes were girls,ages(?13),with knowledge on carcinogenicity,without mothers' raw-eating practice,with knowledge on transmission route,with knowledge on complications and ages(?16),students would have the belief not to do in future.In the decision tree,the knowledge was all in low nodes,and the proportion of the branch with the knowledge in all branches at the same level was small.Chapter 1 in Part 3:Totally,96 education products were collected from 53 organizations.Among them,67 focused on single helminthiasis,of which only 5 aimed to control clonorchiasis.All five products on clonorchiasis targeted general population.Totally,34 products were awarded,but no products targeting clonorchiasis were awarded.Chapter 2 in Part 3:Ten key pieces of knowledge on control of clonorchiasis were extracted,which was then embed into the cartoon,namely "A changing life of liver fluke".Chapter 3 in Part 3:The percentage in intervention group in baseline and evaluation surveys with knowledge on transmission route,early symptoms,complications and carcinogenicity was 15.14%and 92.43%(P<0.001),6.77%and 43.43%(P<0.001),4.78%and 94.82%(P<0.001),and 4.78%and 57.77%(P<0.001),respectively.The corresponding percentage in control was 9.15%and 56.86%(P<0.001),0.65%and 33.33%(P<0.001),2.61%and 42.48%(P<0.001),and 2.61%and 20.92%(P<0.001).The knowledge increased more in intervention school.In intervention school,16 pupils had eaten raw freshwater fish during past 1 year in baseline.However,none among them had eaten during past 6 months in evaluation.In control,35 pupils had eaten raw freshwater fish during past 1 year in baseline,out of which 20 had not eaten during past 6 months in evaluation.The difference between two groups was significant(Fisher's exact test,P<0.01).Among 235 pupils without eating raw freshwater fish during past 1 year in baseline in intervention group,1 had eaten raw freshwater fish during past 6 months in evaluation,namely a proportion of 0.43%(1/235).However,the proportion in control group was 5.08%(6/118).The difference between two groups was significant(Fisher's exact test,P<0.01).As to the belief not to eat raw freshwater fish in future in intervention group,the composition of yes,no and uncertain was 71.31%,17.13%and 11.55%in baseline and 97.21%,1.99%and 0.80%in evaluation(W=60.80,P<0.01).In control group,the corresponding composition was 79.74%,4.58%and 15.69%in baseline and 83.01%,2.61%and 14.38%in evaluation(W=2.73,P>0.05).Conclusions:This study illuminates the transmission characteristics and intensity of clonorchiasis in China and there exist four high transmission provinces in southern and northeastern areas.Then,this study demonstrates the "familial assimilation" in the practice of eating raw freshwater fish,which leads to the establishment of novel intervention theory.Finally,this study verifies the effectiveness of the novel theory in control of clonorchiasis,namely the behavioral intervention strategy targeting children. |
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