Spatiotemporal heterogeneity of schistosomiasis in China's Mainland:Evidence from a multi-stage continuous downscaling sentinel monitoring

Objective:To determine the spatiotemporal distribution of Schistosoma(S.)japonicum infections in humans,livestock,and Oncomelania(O.)hupensis across the endemic foci of China.Methods:Based on multi-stage continuous downscaling of sentinel monitoring,county-based schistosomiasis surveillance data were captured from the national schistosomiasis surveillance sites of China from 2005 to 2019.The data included S.japonicum infections in humans,livestock,and O.hupensis.The spatiotemporal trends for schistosomiasis were detected using a Joinpoint regression model,with a standard deviational ellipse(SDE)tool,which determined the central tendency and dispersion in the spatial distribution of schistosomiasis.Further,more spatiotemporal clusters of S.japonicum infections in humans,livestock,and O.hupensis were evaluated by the Poisson model.Results:The prevalence of S.japonicum human infections decreased from 2.06%to zero based on data of the national schistosomiasis surveillance sites of China from 2005 to 2019,with a reduction from 9.42%to zero for the prevalence of S.japonicum infections in livestock,and from 0.26%to zero for the prevalence of S.japonicum infections in O.hupensis.Analysis using an SDE tool showed that schistosomiasis-affected regions were reduced yearly from 2005 to 2014 in the endemic provinces of Hunan,Hubei,Jiangxi,and Anhui,as well as in the Poyang and Dongting Lake regions.Poisson model revealed 11 clusters of S.japonicum human infections,six clusters of S.japonicum infections in livestock,and nine clusters of S.japonicum infections in O.hupensis.The clusters of human infection were highly consistent with clusters of S.japonicum infections in livestock and O.hupensis.They were in the 5 provinces of Hunan,Hubei,Jiangxi,Anhui,and Jiangsu,as well as along the middle and lower reaches of the Yangtze River.Humans,livestock,and O.hupensis infections with S.japonicum were mainly concentrated in the north of the Hunan Province,south of the Hubei Province,north of the Jiangxi Province,and southwestern portion of Anhui Province.In the 2 mountainous provinces of Sichuan and Yunnan,human,livestock,and O.hupensis infections with S.japonicum were mainly concentrated in the northwestern portion of the Yunnan Province,the Daliangshan area in the south of Sichuan Province,and the hilly regions in the middle of Sichuan Province.Conclusions:A remarkable decline in the disease prevalence of S.japonicum infection was observed in endemic schistosomiasis in China between 2005 and 2019.However,there remains a long-term risk of transmission in local areas,with the highest-risk areas primarily in Poyang Lake and Dongting Lake regions,requiring to focus on vigilance against the rebound of the epidemic.Development of high-sensitivity detection methods and integrating the transmission links such as human and livestock infection,wild animal infection,and O.hupensis into the surveillance-response system will ensure the elimination of schistosomiasis in China by 2030.

Establishment of an indicator framework for the transmission risk of the mountain-type zoonotic visceral leishmaniasis based on the Delphi-entropy weight method

Background: Visceral leishmaniasis (VL) is one of the most important neglected tropical diseases. Although VL was controlled in several regions of China during the last century, the mountain-type zoonotic visceral leishmaniasis (MT-ZVL) has reemerged in the hilly areas of China in recent decades. The purpose of this study was to construct an indicator framework for assessing the risk of the MT-ZVL in China, and to provide guidance for preventing disease.Methods: Based on a literature review and expert interview, a 3-level indicator framework was initially established in November 2021, and 28 experts were selected to perform two rounds of consultation using the Delphi method. The comprehensive weight of the tertiary indicators was determined by the Delphi and the entropy weight methods.Results: Two rounds of Delphi consultation were conducted. Four primary indicators, 11 secondary indicators, and 35 tertiary indicators were identified. The Delphi-entropy weight method was performed to calculate the comprehensive weight of the tertiary indicators. The normalized weights of the primary indicators were 0.268, 0.261, 0.242, and 0.229, respectively, for biological factors, interventions, environmental factors, and social factors. The normalized weights of the top four secondary indicators were 0.122, 0.120, 0.098, and 0.096, respectively, for climatic features, geographical features, sandflies, and dogs. Among the tertiary indicators, the top four normalized comprehensive weights were the population density of sandflies (0.076), topography (0.057), the population density of dogs, including tethering (0.056), and use of bed nets or other protective measures (0.056).Conclusions: An indicator framework of transmission risk assessment for MT-ZVL was established using the Delphientropy weight method. The framework provides a practical tool to evaluate transmission risk in endemic areas.