National Institute Of Parasitic Diseases,Chinese Center For Disease Control And Prevention

Objective:In order to carry out risk assessment during malaria elimination,county-level malaria risk assessment models are to be set up and applied in six cities in Zhejiang,Hainan,Yunnan Provinces and furthermore their malaria risk is stratified,which is to provide a certain reference for the prevention and control of imported malaria.Methods:Literature review is applied to define the concept of malaria risk,explore factors related or causal to malaria risk and build a theoretical framework for malaria risk assessment during malaria elimination.According to the framework,possible influencing factors of malaria risk are summarized and the preliminary the malaria risk assessment index system is established.The Delphi expert consultation meeting is used to collect expert opinions on the malaria risk assessment index system,select indexes and optimize the malaria risk assessment index system to form the final index system.Principal component analysis and Cronbach coefficient are performed on the index scores to test the reliability and validity of the expert consultation questionnaires.Through questionnaire surveys,site visits and surveys,literature review,public statistical data queries,etc.,data on malaria risk assessment indexes is collected at the county level of two cities in Zhejiang Province,Hainan Province,and Yunnan Province for each,with the time range from 2015 to 2019.Indexes are distinguished as the quantitative and qualitative ones and their values are assigned with certain assignment rules.After the data cleaning and collating,the malaria risk assessment index database is built.The evaluation study is multi-scheme,multi-criterion and without outcome variable.To adapt to the characteristics of evaluation study,several subjective and objective comprehensive evaluation methods such as the Delphi method,entropy weight method(EWM),analytic hierarchy process(AHP),and TOPSIS method are used in some combination strategies,to assign weights and values to the indexes.The weighting method is used to figure out the total score,that is,the total malaria risk value,and the score of the malaria risk value of subdivided risks.Combination evaluation of the results obtained from each method is rank-sum ratio(RSR)method.Results:Based on the Recpetivity-Vulnerarbility theory and the process of malaria re-transmission,malaria risk refers to the possibility of malaria occurrence,re-transmission or even re-epidemic in a region.Malaria risk can be subdivided into risk of high-risk groups getting infected(R1),risk of importation(R2),risk of vector receptivity(R3),risk of delay in case detection(R4),risk of inefficiency in management of cases(R5),risk of incapability of maintaing and guaranteeing capacity to eliminate malaria(R6).The final malaria elimination risk assessment index system is composed of 6 primary indexes and 29 secondary indexes.The indexes cover such aspects as mobile population,vectors,awareness of malaria prevention among the population,health service,health resource allocation.The results of Delphi expert consultation meet the consistency requirements.According to results of malaria risk value under four combination strategies of multiple comprehensive evaluation methods,the ranking results of malaria risk values obtained by the analytic hierarchy process(AHP),AHP-TOPSIS(A-T method)are consistent.The results of Delphi-TOPSIS(D-T method)is relatively close to those of the first two.The results of the first three shows that the malaria risk values of Yiwu,Menglian,and Tengchong are ranking the top three while Qingtian,Danzhou,Wanning are ranking behind.Results of Delphi-EWM(D-E method)is not as close to those of the first two as the D-T method.The D-E method shows that Yiwu,Wanning,and Menglian are ranking in the top three.From the perspective of the study areas,R2,R4,and R6 in Yiwu,R5 in Danzhou and Wanning,R4 in Menglian,and R2 in Tengchong are relatively high.From the perspective of subdivided risks,R1 is not significantly different among cities.The regions with higher R2 are Yiwu and Tengchong,and the regions with higher R3 are Danzhou,Wanzhou and Menglian.The region with higher R4 is Menglian.The regions with higher R5 are Danzhou and Wanning.The region with R6 is Qingtian.The combination evaluation results show that Yiwu,Menglian,and Tengchong are stratified as medium-high risk of malaria,,Danzhou as medium-low risk of malaria and Wanning,and Qingtian as low malaria risk.Conclusion:Malaria risk needs to be assessed by integrating multiple factors.Charateristics of malaria risk varies in cities.Malaria risk in land border areas and non-land areas with active cross-national communication is higher than that in other places.In this study,malaria risk assessment model for malaria elimination can well reflect comparison of malaria risk among regions.