| Objective:The objective of this study is to estimate the disease burden of schistosomiasis and assess the cost effectiveness of the integrated control strategy at different control stages for schistosomiasis control in a lake setting,to provide reference for rational allocation of resources and objective evaluation of schistosomiasis prevention and control strategies or measures.Methods:Taking Jiangling County as an example,we collected the epidemiological data related to schistosomiasis from August to December in 2020 from Jiangling station for schistosomiasis control,including snail infested area,area with infected snails,snail infection rate,positive rate of blood test in population,fecal positive rate in population,general information of patients such as gender and age etc.,in Jiangling County spanned from 2009 to 2019.The years lived with disability(YLDs),years of life lost(YLLs)and disability-adjusted life years(DALYs)were calculated with the life quality method based on disability weight(DW)got from cases’ life quality assessment.The temporal trends of DALYs,YLDs,and YLLs of schistosomiasis patients classified by gender and age and the schistosomiasis epidemic situation were estimated by the Annual Percent Change(APC)method through the Joinpoint software.In addition,the annual economic costs of integrated control interventions,including the costs of agricultural,forestry,water conservancy,transportation,land modification projects in Jiangling County from 2009 to 2019,were collected from the perspectives of schistosomiasis control program implementers.All costs from 2009-2019 were calculated and provided in constant 2009 CNY at a discount rate of 3%.Taking "incremental cost/DALYs averted" as the incremental cost effectiveness ratio(ICER),we analyzed the cost effectiveness of the integrated control strategy for schistosomiasis based on county and township level respectively.Results:The epidemic situation of schistosomiasis in Jiangling County had a significant downward trend from 2009 to 2019.The area of snail habitats in the county had dropped from 30.30 million m2 in 2009 to 27.18 million m2 in 2019.No infected snail had been detected since 2012.At present,no acute schistosomiasis case occurs in Jiangling County.The existing cases were caused due to chronic schistosomiasis and advanced schistosomiasis.Furthermore,the proportion of advanced schistosomiasis cases showed an upward trend(trend χ2=2960.60,P<0.001).In addition,the fecal positive rate in the population and adjusted infection rate had declined to zero since 2016,while the cattle infection rate had declined to zero since 2013.The positive rate of blood test and the morbidity rate of schistosomiasis in population had dropped from 14.99%and 4.62%in 2009 to 5.62%and 0.86%in 2019 respectively,showing a downward trend as a whole(trend χ2=7506.00,P<0.001;trend χ2=18737.27,P<0.001).The epidemic situation of schistosomiasis in Jiangling County had reached the lowest level in history.The overall trend of YLDs and DALYs of schistosomiasis in Jiangling County presented a downward trend by gender and age group strata from 2009 to 2019,but the constituent ratio of disease burden caused by advanced schistosomiasis had showed an upward trend(APC=10.6%,P<0.05).At present,the disease burden was mainly caused by advanced schistosomiasis especially in the age group of>60 years old,followed by the 45-59 age groups.Males overloaded higher disease burden of schistosomiasis than females.The disease burden of schistosomiasis in four major epidemic towns including Xionghe,Baimasi,Shagang and Puji town,accounted for 75.51%of the schistosomiasis disease burden in Jiangling County by the end of 2019.In addition,the constituent ratio of DALYs and YLDs showed an upward trend in the age group of≥60 years old(APC>0,P<0.05)and presented a downward trend in the groups of 15-44 and 45-59 years old(APC<0,P<0.05).The constituent ratio of YLLs had no temporal trend among different genders and age groups,with no difference detected.The overall expenditure for schistosomiasis control in Jiangling County from 2009 to 2019 was CNY 603.23 million.Classified by expenditure items,the costs from the land resources department for schistosomiasis control accounted for the largest proportion(about CNY 322.74 million,53.50%),followed by the costs of health activities for schistosomiasis control(about CNY123.12 million,20.41%).In the costs of health department,the costs of mollusciciding accounted for the highest proportion(CNY 36.89 million,29.97%),followed by the costs of livestock disposal and management(CNY 24.09 million,19.57%)and the costs of case treatment(CNY 23.81 million,19.34%),while the costs of health education accounted for the lowest proportion(CNY1.00 million,0.81%).Calculating the costs by the disease control stage,the costs at the stage of infection control(2009-2012),transmission control(2013-2016),and transmission interruption(2017-2019)were approximate CNY 183.51 million,CNY 346.28 million and CNY 73.44 million respectively.The annual investment in the integrated control strategy for schistosomiasis was the least after the county reached the criteria of transmission interruption.Taking the infection control stage as the control,we found that the integrated control strategy at the transmission interruption stage(ICER:CNY-17828.08 per DALY averted,CNY-2977.25 per case averted)was more cost-effective than that at the transmission control stage(ICER:CNY 36851.76 per DALY averted,CNY 7174.50 per case averted).Since 2012,among four townships including Shagang,Baimasi,Puji and Xionghe which were classified as high disease burden group,Xionghe town presented the highest ICER.In middle disease burden group with Haoxue,Zishi,Qinshi and Majiazhai,Haoxue town had the lowest ICER.In addition,among the left towns of the low disease burden group,the ICER presented from low to high successively in Liuheyuan management Area,Sanhu and then Jiangbei farm.Conclusion:The implementation of the integrated control strategy for schistosomiasis had effectively reduced the endemicity of schistosomiasis in Jiangling County.The disease burden caused by schistosomiasis declined annually.However,the constituent ratio of the disease burden caused by advanced schistosomiasis showed an increasing trend,mainly in the age group of 60 years old and above.Interventions and management of the advanced schistosomiasis cases should be strengthened,especially for the elder population with advanced schistosomiasis.With the decline of the schistosomiasis epidemic situation,the integrated control strategy for schistosomiasis had become more cost-effective.To consolidate the achievements obtained and accelerate the process of schistosomiasis elimination,continuous and stable interventions and investments are still required. |
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