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Su Q, Bauer CXC, Bergquist R, Cao Z, Gao F, Zhang Z, Hu Y. Unraveling trends in schistosomiasis: deep learning insights into national control programs in China. Epidemiol Health 2024; 46:e2024039. [PMID: 38514196 PMCID: PMC11369565 DOI: 10.4178/epih.e2024039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024] Open
Abstract
OBJECTIVES To achieve the ambitious goal of eliminating schistosome infections, the Chinese government has implemented diverse control strategies. This study explored the progress of the 2 most recent national schistosomiasis control programs in an endemic area along the Yangtze River in China. METHODS We obtained village-level parasitological data from cross-sectional surveys combined with environmental data in Anhui Province, China from 1997 to 2015. A convolutional neural network (CNN) based on a hierarchical integro-difference equation (IDE) framework (i.e., CNN-IDE) was used to model spatio-temporal variations in schistosomiasis. Two traditional models were also constructed for comparison with 2 evaluation indicators: the mean-squared prediction error (MSPE) and continuous ranked probability score (CRPS). RESULTS The CNN-IDE model was the optimal model, with the lowest overall average MSPE of 0.04 and the CRPS of 0.19. From 1997 to 2011, the prevalence exhibited a notable trend: it increased steadily until peaking at 1.6 per 1,000 in 2005, then gradually declined, stabilizing at a lower rate of approximately 0.6 per 1,000 in 2006, and approaching zero by 2011. During this period, noticeable geographic disparities in schistosomiasis prevalence were observed; high-risk areas were initially dispersed, followed by contraction. Predictions for the period 2012 to 2015 demonstrated a consistent and uniform decrease. CONCLUSIONS The proposed CNN-IDE model captured the intricate and evolving dynamics of schistosomiasis prevalence, offering a promising alternative for future risk modeling of the disease. The comprehensive strategy is expected to help diminish schistosomiasis infection, emphasizing the necessity to continue implementing this strategy.
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Affiliation(s)
- Qing Su
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Xuhui District Center for Disease Control and Prevention, Shanghai, China
| | - Cici Xi Chen Bauer
- Department of Biostatistics and Data Science, University of Texas Health Science Center at Houston, Houston, TX, USA
| | | | - Zhiguo Cao
- Anhui Institute of Parasitic Diseases, Wuhu, China
| | - Fenghua Gao
- Anhui Institute of Parasitic Diseases, Wuhu, China
| | - Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
| | - Yi Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
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Gong Y, Tong Y, Jiang H, Xu N, Yin J, Wang J, Huang J, Chen Y, Jiang Q, Li S, Zhou Y. Three Gorges Dam: the changing trend of snail density in the Yangtze River basin between 1990 and 2019. Infect Dis Poverty 2023; 12:45. [PMID: 37118831 PMCID: PMC10142781 DOI: 10.1186/s40249-023-01095-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 04/19/2023] [Indexed: 04/30/2023] Open
Abstract
BACKGROUND The area of Oncomelania hupensis snail remains around 3.6 billion m2, with newly emerging and reemergent habitats continuing to appear in recent years. This study aimed to explore the long-term dynamics of snail density before and after the operation of Three Gorges Dam (TGD). METHODS Data of snail survey between 1990 and 2019 were collected from electronic databases and national schistosomiasis surveillance. Meta-analysis was conducted to estimate the snail density. Joinpoint model was used to identify the changing trend and inflection point. Inverse distance weighted interpolation (IDW) was used to determine the spatial distribution of recent snail density. RESULTS A total of 3777 snail survey sites with a precise location of village or beach were identified. For the downstream area, snail density peaked in 1998 (1.635/0.11 m2, 95% CI: 1.220, 2.189) and fluctuated at a relatively high level before 2003, then declined steadily from 2003 to 2012. Snail density maintained lower than 0.150/0.11 m2 between 2012 and 2019. Joinpoint model identified the inflection of 2003, and a significant decreasing trend from 2003 to 2012 with an annual percentage change (APC) being - 20.56% (95% CI: - 24.15, - 16.80). For the upstream area, snail density peaked in 2005 (0.760/0.11 m2, 95% CI: 0.479, 1.207) and was generally greater than 0.300/0.11 m2 before 2005. Snail density was generally lower than 0.150/0.11 m2 after 2011. Snail density showed a significant decreasing trend from 1990 to 2019 with an APC being - 6.05% (95% CI: - 7.97, - 7.09), and no inflection was identified. IDW showed the areas with a high snail density existed in Poyang Lake, Dongting Lake, Jianghan Plain, and the Anhui branch of the Yangtze River between 2015 and 2019. CONCLUSIONS Snail density exhibited a fluctuating downward trend in the Yangtze River basin. In the downstream area, the operation of TGD accelerated the decline of snail density during the first decade period, then snail density fluctuated at a relatively low level. There still exists local areas with a high snail density. Long-term control and monitoring of snails need to be insisted on and strengthened.
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Affiliation(s)
- Yanfeng Gong
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Yixin Tong
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Honglin Jiang
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Ning Xu
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Jiangfan Yin
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Jiamin Wang
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Junhui Huang
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Yue Chen
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON, K1G 5Z3, Canada
| | - Qingwu Jiang
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China
| | - Shizhu Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, 200025, China.
- Chinese Center for Tropical Diseases Research, NHC Key Laboratory of Parasite and Vector Biology, Shanghai, 200025, China.
| | - Yibiao Zhou
- Fudan University School of Public Health, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China.
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China.
- Fudan University Center for Tropical Disease Research, Building 8, 130 Dong'an Road, Xuhui District, Shanghai, 200032, China.
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Oso OG, Sunday JO, Odaibo AB. Models for predicting bulinids species habitats in southwestern Nigeria. Parasite Epidemiol Control 2022; 18:e00256. [PMID: 35712128 PMCID: PMC9194844 DOI: 10.1016/j.parepi.2022.e00256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/27/2021] [Accepted: 05/25/2022] [Indexed: 11/04/2022] Open
Abstract
Background Schistosomiasis prevalence is high in southwestern Nigeria and planorbids of the genus Bulinus had been implicated in the transmission of the disease in the area. The knowledge of species distribution in relation to environmental variables will be auspicious in planning control strategies. Methods Satellite imagery and geographic information system (GIS) were used to develop models for predicting the habitats suitable for bulinid species. Monthly snail sample collection was done in twenty-three randomly selected water contact sites using the standard method for a period of two years. Remotely sensed variables such as Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI) were extracted from Landsat TM, ETM+; Slope and Elevation were obtained from digital elevation model (DEM) while Rainfall was retrieved from European Meteorology Research Program. These environmental factors and snail species were integrated into QGIS to predict the potential habitats of different bulinid species using an exploratory regression model. Results The following environmental variables: flat-moderate slope (0.01–15.83), LST (21.1 °C-23.4 °C), NDVI (0.19–0.52), rainfall (> 1569.34 mm) and elevation (1–278 m) contributed to the model used in predicting habitat suitable for bulinids snail intermediate hosts. Exploratory regression models showed that LST, NDVI and slope were predictors of Bulinus globosus and Bulinus jousseaumei; elevation, LST, rainfall and slope were predictors of Bulinus camerunensis; rainfall, NDVI and slope were predictors of B. senegalensis while NDVI and slope were predictors of Bulinus forskalii in the area. Bulinids in the forskalii group showed clustering in middle belt and south. The predictive risk map of B. jousseaumei was similar to the pattern described for B. globosus, but with a high R-square value of 81%. Conclusion The predictive risk models of bulinid species in this study provided a robust output for the study area which could be used as base-line for other areas in that ecological zone. It will be useful in appropriate allocation of scarces resources in the control of schistosomiasis in that environment.
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Su Q, Bergquist R, Ke Y, Dai J, He Z, Gao F, Zhang Z, Hu Y. A comparison of modelling the spatio-temporal pattern of disease: a case study of schistosomiasis japonica in Anhui Province, China. Trans R Soc Trop Med Hyg 2021; 116:555-563. [PMID: 34893918 DOI: 10.1093/trstmh/trab174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/30/2021] [Accepted: 10/27/2021] [Indexed: 11/15/2022] Open
Abstract
The construction of spatio-temporal models can be either descriptive or dynamic. In this study we aim to evaluate the differences in model fitting between a descriptive model and a dynamic model of the transmission for intestinal schistosomiasis caused by Schistosoma japonicum in Guichi, Anhui Province, China. The parasitological data at the village level from 1991 to 2014 were obtained by cross-sectional surveys. We used the fixed rank kriging (FRK) model, a descriptive model, and the integro-differential equation (IDE) model, a dynamic model, to explore the space-time changes of schistosomiasis japonica. In both models, the average daily precipitation and the normalized difference vegetation index are significantly positively associated with schistosomiasis japonica prevalence, while the distance to water bodies, the hours of daylight and the land surface temperature at daytime were significantly negatively associated. The overall root mean square prediction error of the IDE and FRK models was 0.0035 and 0.0054, respectively, and the correlation reflected by Pearson's correlation coefficient between the predicted and observed values for the IDE model (0.71; p<0.01) was larger than that for the FRK model (0.53; p=0.02). The IDE model fits better in capturing the geographic variation of schistosomiasis japonica. Dynamic spatio-temporal models have the advantage of quantifying the process of disease transmission and may provide more accurate predictions.
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Affiliation(s)
- Qing Su
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, China.,Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, China
| | | | - Yongwen Ke
- Schistosomiasis Station of Prevention and Control in Guichi Distirct, Anhui Province, China
| | - Jianjun Dai
- Schistosomiasis Station of Prevention and Control in Guichi Distirct, Anhui Province, China
| | - Zonggui He
- Schistosomiasis Station of Prevention and Control in Guichi Distirct, Anhui Province, China
| | - Fenghua Gao
- Anhui Provincial Institute of Parasitic Diseases, Hefei, China
| | - Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, China.,Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, China
| | - Yi Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, China.,Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, China
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Xia C, Hu Y, Ward MP, Lynn H, Li S, Zhang J, Hu J, Xiao S, Lu C, Li S, Liu Y, Zhang Z. Identification of high-risk habitats of Oncomelania hupensis, the intermediate host of schistosoma japonium in the Poyang Lake region, China: A spatial and ecological analysis. PLoS Negl Trop Dis 2019; 13:e0007386. [PMID: 31206514 PMCID: PMC6597197 DOI: 10.1371/journal.pntd.0007386] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 06/27/2019] [Accepted: 04/12/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Identifying and eliminating snail habitats is the key measure for schistosomiasis control, critical for the nationwide strategy of eliminating schistosomiasis in China. Here, our aim was to construct a new analytical framework to predict high-risk snail habitats based on a large sample field survey for Oncomelania hupensis, providing guidance for schistosomiasis control and prevention. METHODOLOGY/PRINCIPAL FINDINGS Ten ecological models were constructed based on the occurrence data of Oncomelania hupensis and a range of variables in the Poyang Lake region of China, including four presence-only models (Maximum Entropy Models, Genetic Algorithm for rule-set Production, Bioclim and Domain) and six presence-absence models (Generalized Linear Models, Multivariate Adaptive Regression Splines, Flexible Discriminant Analysis, as well as machine algorithmic models-Random Forest, Classification Tree Analysis, Generalized Boosted Model), to predict high-risk snail habitats. Based on overall predictive performance, we found Presence-absence models outperformed the presence-only models and the models based on machine learning algorithms of classification trees showed the highest accuracy. The highest risk was located in the watershed of the River Fu in Yugan County, as well as the watershed of the River Gan and the River Xiu in Xingzi County, covering an area of 52.3 km2. The other high-risk areas for both snail habitats and schistosomiasis were mainly concentrated at the confluence of Poyang Lake and its five main tributaries. CONCLUSIONS/SIGNIFICANCE This study developed a new distribution map of snail habitats in the Poyang Lake region, and demonstrated the critical role of ecological models in risk assessment to directing local field investigation of Oncomelania hupensis. Moreover, this study could also contribute to the development of effective strategies to prevent further spread of schistosomiasis from endemic areas to non-endemic areas.
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Affiliation(s)
- Congcong Xia
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
- Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, P. R. China
- Department of Infection Control Administration, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P. R. China
| | - Yi Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
- Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, P. R. China
| | - Michael P. Ward
- Sydney School of Veterinary Science, The University of Sydney, Sydney, Australia
| | - Henry Lynn
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
| | - Si Li
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
| | - Jun Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
| | - Jian Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
| | - Shuang Xiao
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
| | - Chengfang Lu
- Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, Nanchang, P. R. China
| | - Shizhu Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, P. R. China
| | - Ying Liu
- Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, Nanchang, P. R. China
| | - Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, P. R. China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, P. R. China
- Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, P. R. China
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Araujo Navas AL, Soares Magalhães RJ, Osei F, Fornillos RJC, Leonardo LR, Stein A. Modelling local areas of exposure to Schistosoma japonicum in a limited survey data environment. Parasit Vectors 2018; 11:465. [PMID: 30103810 PMCID: PMC6090730 DOI: 10.1186/s13071-018-3039-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/27/2018] [Indexed: 01/14/2023] Open
Abstract
Background Spatial modelling studies of schistosomiasis (SCH) are now commonplace. Covariate values are commonly extracted at survey locations, where infection does not always take place, resulting in an unknown positional exposure mismatch. The present research aims to: (i) describe the nature of the positional exposure mismatch in modelling SCH helminth infections; (ii) delineate exposure areas to correct for such positional mismatch; and (iii) validate exposure areas using human positive cases. Methods To delineate exposure areas to Schistosoma japonicum, a spatial Bayesian network (sBN) was constructed. It uses data on exposure risk factors such as: potential sites for snails’ accessibility, geographical distribution of snail infection rate, and cost of the community to access nearby water bodies. Prior and conditional probabilities were obtained from the literature and inserted as weights based on their relative contribution to exposure; these probabilities were then used to calculate joint probabilities of exposure within the sBN. Results High values of probability of S. japonicum exposure correspond to polygons where snails could potentially be present, for instance in wet soils and areas with low slopes, but also where people can easily access water bodies. Low correlation (R2 = 0.3) was found between the percentage of human cases and the delineated probabilities of exposure when validation buffers are generated over the human cases. Conclusions The utility of a probabilistic method for the identification of exposure areas for S. japonicum, with wider application for other water-borne infections, was demonstrated. From a public health perspective, the schistosomiasis exposure sBN developed in this study could be used to guide local schistosomiasis control teams to specific potential areas of exposure, and improve efficiency of mass drug administration campaigns in places where people are likely to be exposed to the infection. Electronic supplementary material The online version of this article (10.1186/s13071-018-3039-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea L Araujo Navas
- Faculty of Geo-information Science and Earth Observation (ITC), University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands.
| | - Ricardo J Soares Magalhães
- UQ Spatial Epidemiology Laboratory, School of Veterinary Science, The University of Queensland, QLD, Gatton, 4343, Australia.,Child Health and Environment Program, Child Health Research Centre, The University of Queensland, QLD, South Brisbane, 4101, Australia
| | - Frank Osei
- Faculty of Geo-information Science and Earth Observation (ITC), University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Raffy Jay C Fornillos
- Institute of Biology, College of Science, University of the Philippines Diliman, 1101, Quezon, Philippines
| | - Lydia R Leonardo
- Department of Parasitology, College of Public Health, University of the Philippines Manila, 1000, Manila, Philippines
| | - Alfred Stein
- Faculty of Geo-information Science and Earth Observation (ITC), University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
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Sun LP, Wang W, Zuo YP, Zhang ZQ, Hong QB, Yang GJ, Zhu HR, Liang YS, Yang HT. An integrated environmental improvement of marshlands: impact on control and elimination of schistosomiasis in marshland regions along the Yangtze River, China. Infect Dis Poverty 2017; 6:72. [PMID: 28330510 PMCID: PMC5361825 DOI: 10.1186/s40249-017-0287-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Schistosomiasis is a global snail-transmitted infectious disease of poverty. Transmission control had been achieved in China in 2015 after the control efforts for over 60 years. Currently, the remaining core regions endemic for Schistosoma japonicum are mainly located in the marshland and lake regions along the Yangtze River basin. METHODS During the period from 2001 through 2015, an integrated environmental improvement of the marshlands was carried out through the implementation of industrial, agricultural and resources development projects in Yizheng County along the Yangtze River. S. japonicum infection in humans, livestock and snails was estimated by serology, stool examination, hatching technique and microscopy during the 15-year study period to evaluate the effect of the integrated environmental improvement on control and elimination of schistosomiasis. RESULTS A 0.05% overall rate of S. japonicum infection was observed in snails during the 15-year study period, and no infected snails were detected since 2012. The overall prevalence of S. japonicum infection was 0.09% in humans during the study period, and no human infection was found since 2012. In addition, only 13 bovines were identified with S. japonicum infection in 2003 during the 15-year study period, and since 2004, no infection was found in livestock. CONCLUSION The results of the present study demonstrate that the implementation of industrial, agricultural and water resources development projects, not only alters snail habitats in marshland regions, and promotes local economic development, which appears a win-to-win strategy to block the transmission of S. japonicum and accelerate socio-economic development along the Yangtze River.
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Affiliation(s)
- Le-Ping Sun
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - Wei Wang
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - Yin-Ping Zuo
- Yangzhou Municipal Center for Disease Control and Prevention, No. 36 Yanfu East Road, Yangzhou City, Jiangsu Province 225000 China
| | - Zheng-Qiu Zhang
- Yizheng County Center for Disease Control and Prevention, NO. 1 Jiankang Road, Yangzhou City, Jiangsu Province 211440 China
| | - Qing-Biao Hong
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - Guo-Jing Yang
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - Hong-Ru Zhu
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - You-Sheng Liang
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
| | - Hai-Tao Yang
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
- Jiangsu Institute of Parasitic Diseases, No. 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064 China
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Mapping Soil Transmitted Helminths and Schistosomiasis under Uncertainty: A Systematic Review and Critical Appraisal of Evidence. PLoS Negl Trop Dis 2016; 10:e0005208. [PMID: 28005901 PMCID: PMC5179027 DOI: 10.1371/journal.pntd.0005208] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/23/2016] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Spatial modelling of STH and schistosomiasis epidemiology is now commonplace. Spatial epidemiological studies help inform decisions regarding the number of people at risk as well as the geographic areas that need to be targeted with mass drug administration; however, limited attention has been given to propagated uncertainties, their interpretation, and consequences for the mapped values. Using currently published literature on the spatial epidemiology of helminth infections we identified: (1) the main uncertainty sources, their definition and quantification and (2) how uncertainty is informative for STH programme managers and scientists working in this domain. METHODOLOGY/PRINCIPAL FINDINGS We performed a systematic literature search using the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) protocol. We searched Web of Knowledge and PubMed using a combination of uncertainty, geographic and disease terms. A total of 73 papers fulfilled the inclusion criteria for the systematic review. Only 9% of the studies did not address any element of uncertainty, while 91% of studies quantified uncertainty in the predicted morbidity indicators and 23% of studies mapped it. In addition, 57% of the studies quantified uncertainty in the regression coefficients but only 7% incorporated it in the regression response variable (morbidity indicator). Fifty percent of the studies discussed uncertainty in the covariates but did not quantify it. Uncertainty was mostly defined as precision, and quantified using credible intervals by means of Bayesian approaches. CONCLUSION/SIGNIFICANCE None of the studies considered adequately all sources of uncertainties. We highlighted the need for uncertainty in the morbidity indicator and predictor variable to be incorporated into the modelling framework. Study design and spatial support require further attention and uncertainty associated with Earth observation data should be quantified. Finally, more attention should be given to mapping and interpreting uncertainty, since they are relevant to inform decisions regarding the number of people at risk as well as the geographic areas that need to be targeted with mass drug administration.
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Hu Y, Li S, Xia C, Chen Y, Lynn H, Zhang T, Xiong C, Chen G, He Z, Zhang Z. Assessment of the national schistosomiasis control program in a typical region along the Yangtze River, China. Int J Parasitol 2016; 47:21-29. [PMID: 27866904 DOI: 10.1016/j.ijpara.2016.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/13/2016] [Accepted: 09/22/2016] [Indexed: 11/19/2022]
Abstract
Schistosomiasis remains a major public health problem in eastern China, particularly along the Yangtze River Basin. The latest national schistosomiasis control program (NSCP) was implemented in 2005 with the main goal of reducing the rate of infection to less than 5% by 2008 and 1% by 2015. To assess the progress, we applied a Bayesian spatio-temporal model to describe dynamics of schistosomiasis in Guichi, Anhui Province, China, using annual parasitological and environmental data collected within 41 sample villages for the period 2005-2011. Predictive maps of schistosomiasis showed that the disease prevalence remains constant and low. Results of uncertainty analysis, in the form of probability contour maps (PCMs), indicated that the first goal of "infection rate less than 5% by 2008" was fully achieved in the study area. More longitudinal data for schistosomiasis are needed for the assessment of the second goal of "infection rate less than 1% by 2015". Compared with the traditional way of mapping uncertainty (e.g., variance or mean-square error), our PCMs provide more realistic information for schistosomiasis control.
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Affiliation(s)
- Yi Hu
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Si Li
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Congcong Xia
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Yue Chen
- School of Epidemiology, Pubic Health and Preventive Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, Ontario, Canada
| | - Henry Lynn
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Tiejun Zhang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Chenglong Xiong
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China
| | - Gengxin Chen
- Schistosomiasis Station of Prevention and Control in Guichi Distirct, Anhui Province, China
| | - Zonggui He
- Schistosomiasis Station of Prevention and Control in Guichi Distirct, Anhui Province, China
| | - Zhijie Zhang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China; Collaborative Innovation Center of Social Risks Governance in Health, School of Public Health, Fudan University, Shanghai, China.
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10
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Zhang Z, Manjourides J, Cohen T, Hu Y, Jiang Q. Spatial measurement errors in the field of spatial epidemiology. Int J Health Geogr 2016; 15:21. [PMID: 27368370 PMCID: PMC4930612 DOI: 10.1186/s12942-016-0049-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 06/15/2016] [Indexed: 11/29/2022] Open
Abstract
Background Spatial epidemiology has been aided by advances in geographic information systems, remote sensing, global positioning systems and the development of new statistical methodologies specifically designed for such data. Given the growing popularity of these studies, we sought to review and analyze the types of spatial measurement errors commonly encountered during spatial epidemiological analysis of spatial data.
Methods Google Scholar, Medline, and Scopus databases were searched using a broad set of terms for papers indexed by a term indicating location (space or geography or location or position) and measurement error (measurement error or measurement inaccuracy or misclassification or uncertainty): we reviewed all papers appearing before December 20, 2014. These papers and their citations were reviewed to identify the relevance to our review. Results We were able to define and classify spatial measurement errors into four groups: (1) pure spatial location measurement errors, including both non-instrumental errors (multiple addresses, geocoding errors, outcome aggregations, and covariate aggregation) and instrumental errors; (2) location-based outcome measurement error (purely outcome measurement errors and missing outcome measurements); (3) location-based covariate measurement errors (address proxies); and (4) Covariate-Outcome spatial misaligned measurement errors. We propose how these four classes of errors can be unified within an integrated theoretical model and possible solutions were discussed. Conclusion Spatial measurement errors are ubiquitous threat to the validity of spatial epidemiological studies. We propose a systematic framework for understanding the various mechanisms which generate spatial measurement errors and present practical examples of such errors.
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Affiliation(s)
- Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, 200032, China. .,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, 200032, China.
| | - Justin Manjourides
- Department of Health Sciences, Northeastern University, Boston, MA, 02115, USA
| | - Ted Cohen
- Department of Epidemiology and the Center for Communicable Disease Dynamics, School of Public Health, Harvard University, Boston, MA, 02115, USA.,Division of Global Health Equity, Brigham and Women's Hospital, Boston, MA, 02115, USA.,Harvard Medical School, Boston, MA, 02115, USA
| | - Yi Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, 200032, China
| | - Qingwu Jiang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, 200032, China
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11
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Hu Y, Li R, Chen Y, Gao F, Wang Q, Zhang S, Zhang Z, Jiang Q. Shifts in the spatiotemporal dynamics of schistosomiasis: a case study in Anhui Province, China. PLoS Negl Trop Dis 2015; 9:e0003715. [PMID: 25881189 PMCID: PMC4400088 DOI: 10.1371/journal.pntd.0003715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 03/20/2015] [Indexed: 11/26/2022] Open
Abstract
Background The Chinese national surveillance system showed that the risk of Schistosoma japonicum infection fluctuated temporally. This dynamical change might indicate periodicity of the disease, and its understanding could significantly improve targeted interventions to reduce the burden of schistosomiasis. The goal of this study was to investigate how the schistosomiasis risk varied temporally and spatially in recent years. Methodology/Principal Findings Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China. A multivariate autoregressive model, combined with principal oscillation pattern (POP) analysis, was used to evaluate the spatio-temporal variation of schistosomiasis risk. Results showed that the temporal changes of schistosomiasis risk in the study area could be decomposed into two sustained damped oscillatory modes with estimated period of approximately 2.5 years. The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation. The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards. Conclusion The POP analysis characterized the variations of schistosomiasis risk over space and time and demonstrated that the disease mainly varied temporally along the Yangtze River. The schistosomiasis risk declined periodically with a temporal fluctuation. Whether it resulted from previous national control strategies on schistosomiasis needs further investigations. We investigated changes in dynamics of schistosomiasis transmission over space and time in Anhui Province of East China. Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997–2010. A multivariate autoregressive model, combined with principal oscillation pattern (POP) analysis, was used to evaluate the spatio-temporal variation of schistosomiasis risk. The schistosomiasis risk changed temporally as a damped oscillatory mode with a fluctuation, indicating that the disease risk declined periodically but with a temporal ascent during the study period. This change might result from national control strategies on schistosomiasis. The POP analysis also demonstrated a shifting spatial pattern of schistosomiasis along the Yangtze River. The POP method is commonly used in geosciences but not in epidemiology. Our analysis based on the approach provided new insights into the research of schistosomiasis transmission. The utility of such methods for addressing epidemiological problems will grow as more large-scale datasets become readily available.
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Affiliation(s)
- Yi Hu
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
| | - Rui Li
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
| | - Yue Chen
- School of Epidemiology, Public Health and Preventive Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Fenghua Gao
- Anhui Institute of Parasitic Diseases, Wuhu, China
| | - Qizhi Wang
- Anhui Institute of Parasitic Diseases, Wuhu, China
| | | | - Zhijie Zhang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
- Biomedical Statistical Center, Fudan University, Shanghai, China
- * E-mail:
| | - Qingwu Jiang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China
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12
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Chen YY, Huang XB, Xiao Y, Jiang Y, Shan XW, Zhang J, Cai SX, Liu JB. Spatial analysis of Schistosomiasis in Hubei Province, China: a GIS-based analysis of Schistosomiasis from 2009 to 2013. PLoS One 2015; 10:e0118362. [PMID: 25849567 PMCID: PMC4388649 DOI: 10.1371/journal.pone.0118362] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/15/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Schistosomiasis remains a major public health problem in China. The major endemic areas are located in the lake and marshland regions of southern China, particularly in areas along the middle and low reach of the Yangtze River. Spatial analytical techniques are often used in epidemiology to identify spatial clusters in disease regions. This study assesses the spatial distribution of schistosomiasis and explores high-risk regions in Hubei Province, China to provide guidance on schistosomiasis control in marshland regions. METHODS In this study, spatial autocorrelation methodologies, including global Moran's I and local Getis-Ord statistics, were utilized to describe and map spatial clusters and areas where human Schistosoma japonicum infection is prevalent at the county level in Hubei province. In addition, linear logistic regression model was used to determine the characteristics of spatial autocorrelation with time. RESULTS The infection rates of S. japonicum decreased from 2009 to 2013. The global autocorrelation analysis results on the infection rate of S. japonicum for five years showed statistical significance (Moran's I > 0, P < 0.01), which suggested that spatial clusters were present in the distribution of S. japonicum infection from 2009 to 2013. Local autocorrelation analysis results showed that the number of highly aggregated areas ranged from eight to eleven within the five-year analysis period. The highly aggregated areas were mainly distributed in eight counties. CONCLUSIONS The spatial distribution of human S. japonicum infections did not exhibit a temporal change at the county level in Hubei Province. The risk factors that influence human S. japonicum transmission may not have changed after achieving the national criterion of infection control. The findings indicated that spatial-temporal surveillance of S. japonicum transmission plays a significant role on schistosomiasis control. Timely and integrated prevention should be continued, especially in the Yangtze River Basin of Jianghan Plain area.
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Affiliation(s)
- Yan-Yan Chen
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Xi-Bao Huang
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Ying Xiao
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Yong Jiang
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Xiao-wei Shan
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Juan Zhang
- Hubei Center for Disease Control and Prevention, Wuhan, China
| | - Shun-Xiang Cai
- Hubei Center for Disease Control and Prevention, Wuhan, China
- * E-mail: (SXC); (JBL)
| | - Jian-Bing Liu
- Hubei Center for Disease Control and Prevention, Wuhan, China
- * E-mail: (SXC); (JBL)
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13
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Spatio-temporal transmission and environmental determinants of Schistosomiasis Japonica in Anhui Province, China. PLoS Negl Trop Dis 2015; 9:e0003470. [PMID: 25659112 PMCID: PMC4319937 DOI: 10.1371/journal.pntd.0003470] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 12/11/2014] [Indexed: 11/16/2022] Open
Abstract
Background Schistosomiasis japonica still remains of public health and economic significance in China, especially in the lake and marshland areas along the Yangtze River Basin, where the control of transmission has proven difficult. In the study, we investigated spatio-temporal variations of S. japonicum infection risk in Anhui Province and assessed the associations of the disease with key environmental factors with the aim of understanding the mechanism of the disease and seeking clues to effective and sustainable schistosomiasis control. Methodology/Principal Findings Infection data of schistosomiasis from annual conventional surveys were obtained at the village level in Anhui Province, China, from 2000 to 2010 and used in combination with environmental data. The spatio-temporal kriging model was used to assess how these environmental factors affected the spatio-temporal pattern of schistosomiasis risk. Our results suggested that seasonal variation of the normalized difference vegetation index (NDVI), seasonal variation of land surface temperature at daytime (LSTD), and distance to the Yangtze River were negatively significantly associated with risk of schistosomiasis. Predictive maps showed that schistosomiasis prevalence remained at a low level and schistosomiasis risk mainly evolved along the Yangtze River. Schistosomiasis risk also followed a focal spatial pattern, fluctuating temporally with a peak (the largest spatial extent) in 2005 and then contracting gradually but with a scattered distribution until 2010. Conclusion The fitted spatio-temporal kriging model can capture variations of schistosomiasis risk over space and time. Combined with techniques of geographic information system (GIS) and remote sensing (RS), this approach facilitates and enriches risk modeling of schistosomiasis, which in turn helps to identify prior areas for effective and sustainable control of schistosomiasis in Anhui Province and perhaps elsewhere in China. Schistosomiasis japonica is one of the most serious parasitic diseases in China. It is estimated that more than 50 million people are still at risk, especially those living in the lake and marshland areas along the Yangtze River Basin. The Chinese government has made great efforts to implement schistosomiasis control programs since 1950s. The latest, major two programs are the 10-year World Bank Loan Project (WBLP) terminated in 2001, which was based on large-scale chemotherapy, and the national integrated control strategy implemented since 2005, which was aimed at reducing the roles of bovines and humans as infection sources. Based on spatio-temporal analyses of the S. japonicum infection prevalence data during 2000–2010 in Anhui Province, we found schistosomiasis prevalence remained at a low level but the spatial distribution of the disease became widely scattered at the later stage of the study period, suggesting that the integrated program could not fully effectively reduce the spatial extent of schistosomiasis risk. To achieve an effective and sustainable control strategy, we emphasize the need to control snail habitats within areas of high schistosomiasis risk.
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14
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Xu JF, Lv S, Wang QY, Qian MB, Liu Q, Bergquist R, Zhou XN. Schistosomiasis japonica: modelling as a tool to explore transmission patterns. Acta Trop 2015; 141:213-22. [PMID: 25004441 DOI: 10.1016/j.actatropica.2014.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 06/22/2014] [Accepted: 06/27/2014] [Indexed: 11/26/2022]
Abstract
Modelling is an important tool for the exploration of Schistosoma japonicum transmission patterns. It provides a general theoretical framework for decision-makers and lends itself specifically to assessing the progress of the national control programme by following the outcome of surveys. The challenge of keeping up with the many changes of social, ecological and environmental factors involved in control activities is greatly facilitated by modelling that can also indicate which activities are critical and which are less important. This review examines the application of modelling tools in the epidemiological study of schistosomiasis japonica during the last 20 years and explores the application of enhanced models for surveillance and response. Updated and timely information for decision-makers in the national elimination programme is provided but, in spite of the new modelling techniques introduced, many questions remain. Issues on application of modelling are discussed with the view to improve the current situation with respect to schistosomiasis japonica.
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15
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Qiu J, Li R, Xu X, Yu C, Xia X, Hong X, Chang B, Yi F, Shi Y. Identifying determinants of Oncomelania hupensis habitats and assessing the effects of environmental control strategies in the plain regions with the waterway network of China at the microscale. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2014; 11:6571-85. [PMID: 25003174 PMCID: PMC4078596 DOI: 10.3390/ijerph110606571] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 11/21/2022]
Abstract
This study aims to identify the landscape ecological determinants related to Oncomelania hupensis distribution, map the potential high risk of O. hupensis habitats at the microscale, and assess the effects of two environmental control strategies. Sampling was performed on 242 snail sites and 726 non-snail sites throughout Qianjiang City, Hubei Province, China. An integrated approach of landscape pattern analysis coupled with multiple logistic regression modeling was applied to investigate the effects of environmental factors on snail habitats. The risk probability of snail habitats positively correlated with patch fractal dimension (FD), paddy farm land proportion, and wetness index but inversely correlated with categorized normalized difference vegetation index (NDVI) and elevation. These findings indicate that FD can identify irregular features (e.g., irrigation ditches) in plain regions and that a moderate NDVI increases the microscale risk probability. Basing on the observed determinants, we predicted a map showing high-risk areas of snail habitats and simulated the effects of conduit hardening and paddy farming land rotation to dry farming land. The two approaches were confirmed effective for snail control. These findings provide an empirical basis for health professionals in local schistosomiasis control stations to identify priority areas and promising environmental control strategies for snail control and prevention.
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Affiliation(s)
- Juan Qiu
- Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China; E-Mails: (J.Q.); (B.C.); (F.Y.); (Y.S.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rendong Li
- Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China; E-Mails: (J.Q.); (B.C.); (F.Y.); (Y.S.)
| | - Xingjian Xu
- Hubei Provincial Center for Disease Control and Prevention, Wuhan 430079, Hubei Province, China; E-Mails: (X.Xu); (X.Xia); (X.H.)
| | - Chuanhua Yu
- School of Public Health & Global Health Institute, Wuhan University, Wuhan 430072, Hubei Province, China; E-Mail:
| | - Xin Xia
- Hubei Provincial Center for Disease Control and Prevention, Wuhan 430079, Hubei Province, China; E-Mails: (X.Xu); (X.Xia); (X.H.)
| | - Xicheng Hong
- Hubei Provincial Center for Disease Control and Prevention, Wuhan 430079, Hubei Province, China; E-Mails: (X.Xu); (X.Xia); (X.H.)
| | - Bianrong Chang
- Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China; E-Mails: (J.Q.); (B.C.); (F.Y.); (Y.S.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fengjia Yi
- Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China; E-Mails: (J.Q.); (B.C.); (F.Y.); (Y.S.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanyuan Shi
- Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China; E-Mails: (J.Q.); (B.C.); (F.Y.); (Y.S.)
- University of Chinese Academy of Sciences, Beijing 100049, China
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Hu Y, Xiong C, Zhang Z, Luo C, Ward M, Gao J, Zhang L, Jiang Q. Dynamics of spatial clustering of schistosomiasis in the Yangtze River Valley at the end of and following the World Bank Loan Project. Parasitol Int 2014; 63:500-5. [PMID: 24530858 DOI: 10.1016/j.parint.2014.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 12/12/2013] [Accepted: 01/28/2014] [Indexed: 01/08/2023]
Abstract
The 10-year (1992-2001) World Bank Loan Project (WBLP) contributed greatly to schistosomiasis control in China. However, the re-emergence of schistosomiasis in recent years challenged the long-term progress of the WBLP strategy. In order to gain insight in the long-term progress of the WBLP, the spatial pattern of the epidemic was investigated in the Yangtze River Valley between 1999-2001 and 2007-2008. Two spatial cluster methods were jointly used to identify spatial clusters of cases. The magnitude and number of clusters varied during 1999-2001. It was found that prevalence of schistosomiasis had been greatly reduced and maintained at a low level during 2007-2008, with little change. Besides, spatial clusters most frequently occurred within 16 counties in the Dongting Lake region and within 5 counties in the Poyang Lake region. These findings precisely pointed out the prior places for future public health planning and resource allocation of schistosomiasis.
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Affiliation(s)
- Yi Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, People's Republic of China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, People's Republic of China
| | - Chenglong Xiong
- Department of Microbiology and Health, School of Public Health, Fudan University, Shanghai, People's Republic of China
| | - Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, People's Republic of China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, People's Republic of China.
| | - Can Luo
- Department of Environmental Art and Architecture, Changsha Environmental Protection Vocational Technical College, Hunan, People's Republic of China
| | - Michael Ward
- Faculty of Veterinary Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Jie Gao
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China
| | - Lijuan Zhang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China
| | - Qingwu Jiang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, People's Republic of China
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17
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Zhang Z, Bergquist R, Chen D, Yao B, Wang Z, Gao J, Jiang Q. Identification of parasite-host habitats in Anxiang county, Hunan Province, China based on multi-temporal China-Brazil earth resources satellite (CBERS) images. PLoS One 2013; 8:e69447. [PMID: 23922712 PMCID: PMC3726693 DOI: 10.1371/journal.pone.0069447] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/08/2013] [Indexed: 11/19/2022] Open
Abstract
Remote sensing is a promising technique for monitoring the distribution and dynamics of various vector-borne diseases. In this study, we used the multi-temporal CBERS images, obtained free of charge, to predict the habitats of the snail Oncomelania hupensis, the sole intermediate host of schistosomiasis japonica, a snail-borne parasitic disease of considerable public health in China. Areas of suitable snail habitats were identified based on the normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI), and the predictive model was tested against sites (snails present or absent) that were surveyed directly for O. hupensis. The model performed well (sensitivity and specificity were 63.64% and 78.09%, respectively), and with further development, we may provide an accurate, inexpensive tool for the broad-scale monitoring and control of schistosomiasis, and other similar vector-borne diseases.
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Affiliation(s)
- Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China.
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Hu Y, Zhang Z, Chen Y, Wang Z, Gao J, Tao B, Jiang Q, Jiang Q. Spatial pattern of schistosomiasis in Xingzi, Jiangxi Province, China: the effects of environmental factors. Parasit Vectors 2013; 6:214. [PMID: 23880253 PMCID: PMC3726341 DOI: 10.1186/1756-3305-6-214] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 07/18/2013] [Indexed: 11/29/2022] Open
Abstract
Background The recent rebounds of schistosomiasis in the middle and lower reaches of the Yangtze River pose a challenge to the current control strategies. In this study, identification of potential high risk snail habitats was proposed, as an alternative sustainable control strategy, in Xingzi County, China. Parasitological data from standardized surveys were available for 36,208 locals (aged between 6–65 years) from 42 sample villages across the county and used in combination with environmental data to investigate the spatial pattern of schistosomiasis risks. Methods Environmental factors measured at village level were examined as possible risk factors by fitting a logistic regression model to schsitosomiasis risk. The approach of ordinary kriging was then used to predict the prevalence of schistosomiasis over the whole county. Results Risk analysis indicated that distance to snail habitat and wetland, rainfall, land surface temperature, hours of daylight, and vegetation are significantly associated with infection and the residual spatial pattern of infection showed no spatial correlation. The predictive map illustrated that high risk regions were located close to Beng Lake, Liaohuachi Lake, and Shixia Lake. Conclusions Those significant environmental factors can perfectly explain spatial variation in infection and the high risk snail habitats delineated by the predicted map of schistosomiasis risks will help local decision-makers to develop a more sustainable control strategy.
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Affiliation(s)
- Yi Hu
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China
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Zhou YB, Liang S, Chen GX, Rea C, Han SM, He ZG, Li YP, Wei JG, Zhao GM, Jiang QW. Spatial-temporal variations of Schistosoma japonicum distribution after an integrated national control strategy: a cohort in a marshland area of China. BMC Public Health 2013; 13:297. [PMID: 23556428 PMCID: PMC3621803 DOI: 10.1186/1471-2458-13-297] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 03/26/2013] [Indexed: 11/25/2022] Open
Abstract
Background Schistosomiasis transmission is typically focal. Understanding spatial variations of Schistosoma infections and their associated factors is important to help to invent site-specific intervention strategies. Methods A five-year longitudinal study was carried out prospectively in 12 natural villages, Guichi district of Anhui province. A GIS-based spatial analysis was conducted to identify geographic distribution patterns of schistosomiasis infections at the household scale. Results The results of the spatial autocorrelation analysis for 2005 showed that there were significant spatial clusters of human infections at the household level, and these results were in agreement with that of the spatial scan statistic. As prevalence of infections in humans decreased over the course of control, the spatial distribution of these infections became less heterogeneous. Conclusions The findings imply that it may be necessary to re-assess risk factors of S. japonicum transmission over the course of control and to adjust accordingly control measures in the communities.
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Affiliation(s)
- Yi-Biao Zhou
- Department of Epidemiology, School of Public Health, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
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Identification of high-risk regions for schistosomiasis in the Guichi region of China: an adaptive kernel density estimation-based approach. Parasitology 2013; 140:868-75. [PMID: 23469774 DOI: 10.1017/s0031182013000048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Identification of high-risk regions of schistosomiasis is important for rational resource allocation and effective control strategies. We conducted the first study to apply the newly developed method of adaptive kernel density estimation (KDE)-based spatial relative risk function (sRRF) to detect the high-risk regions of schistosomiasis in the Guichi region of China and compared it with the fixed KDE-based sRRF. We found that the adaptive KDE-based sRRF had a better ability to depict the heterogeneity of risk regions, but was more sensitive to altering the user-defined smoothing parameters. Specifically, the impact of bandwidths on the estimated risk value and risk significance (P value) was higher for the adaptive KDE-based sRRF, but lower on the estimated risk variation standard error (s.e.) compared with the fixed KDE-based sRRF. Based on this application the adaptive and fixed KDE-based sRRF have their respective advantages and disadvantages and the joint application of the two approaches can warrant the best possible identification of high-risk subregions of diseases.
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Zhang Z, Ward M, Gao J, Wang Z, Yao B, Zhang T, Jiang Q. Remote sensing and disease control in China: past, present and future. Parasit Vectors 2013; 6:11. [PMID: 23311958 PMCID: PMC3558403 DOI: 10.1186/1756-3305-6-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 01/05/2013] [Indexed: 11/28/2022] Open
Abstract
Satellite measurements have distinct advantages over conventional ground measurements because they can collect the information repeatedly and automatically. Since 1970 globally and 1985 in China, the availability of remote sensing (RS) techniques has steadily grown and they are becoming increasingly important to improve our understanding of human health. This paper gives the first detailed overview on the developments of RS applications for disease control in China. The problems, challenges and future directions are also discussed with an aim of guiding prospective studies.
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Affiliation(s)
- Zhijie Zhang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
| | - Michecal Ward
- Faculty of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Jie Gao
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
| | - Zengliang Wang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
| | - Baodong Yao
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
| | - Tiejun Zhang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
| | - Qingwu Jiang
- Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
- Key Laboratory of Public Health Safety, Ministry of Education, Shanghai 200032, People’s Republic of China
- Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai 200032, People’s Republic of China
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Zhang Z, Zhu R, Ward MP, Xu W, Zhang L, Guo J, Zhao F, Jiang Q. Long-term impact of the World Bank Loan Project for schistosomiasis control: a comparison of the spatial distribution of schistosomiasis risk in China. PLoS Negl Trop Dis 2012; 6:e1620. [PMID: 22530073 PMCID: PMC3328430 DOI: 10.1371/journal.pntd.0001620] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/21/2012] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND The World Bank Loan Project (WBLP) for controlling schistosomiasis in China was implemented during 1992-2001. Its short-term impact has been assessed from non-spatial perspective, but its long-term impact remains unclear and a spatial evaluation has not previously been conducted. Here we compared the spatial distribution of schistosomiasis risk using national datasets in the lake and marshland regions from 1999-2001 and 2007-2008 to evaluate the long-term impact of WBLP strategy on China's schistosomiasis burden. METHODOLOGY/PRINCIPAL FINDINGS A hierarchical Poisson regression model was developed in a Bayesian framework with spatially correlated and uncorrelated heterogeneities at the county-level, modeled using a conditional autoregressive prior structure and a spatially unstructured Gaussian distribution, respectively. There were two important findings from this study. The WBLP strategy was found to have a good short-term impact on schistosomiasis control, but its long-term impact was not ideal. It has successfully reduced the morbidity of schistosomiasis to a low level, but can not contribute further to China's schistosomiasis control because of the current low endemic level. A second finding is that the WBLP strategy could not effectively compress the spatial distribution of schistosomiasis risk. To achieve further reductions in schistosomiasis-affected areas, and for sustainable control, focusing on the intermediate host snail should become the next step to interrupt schistosomiasis transmission within the two most affected regions surrounding the Dongting and Poyang Lakes. Furthermore, in the lower reaches of the Yangtze River, the WBLP's morbidity control strategy may need to continue for some time until snails in the upriver provinces have been well controlled. CONCLUSION It is difficult to further reduce morbidity due to schistosomiasis using a chemotherapy-based control strategy in the lake and marshland regions of China because of the current low endemic levels of infection. The future control strategy for schistosomiasis should instead focus on a snail-based integrated control strategy to maintain the program achievements and sustainably reduce the burden of schistosomiasis in China.
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Affiliation(s)
- Zhijie Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China.
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Zhang Z, Chen D, Liu W, Racine JS, Ong S, Chen Y, Zhao G, Jiang Q. Nonparametric evaluation of dynamic disease risk: a spatio-temporal kernel approach. PLoS One 2011; 6:e17381. [PMID: 21423612 PMCID: PMC3057986 DOI: 10.1371/journal.pone.0017381] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 01/31/2011] [Indexed: 11/19/2022] Open
Abstract
Quantifying the distributions of disease risk in space and time jointly is a key element for understanding spatio-temporal phenomena while also having the potential to enhance our understanding of epidemiologic trajectories. However, most studies to date have neglected time dimension and focus instead on the "average" spatial pattern of disease risk, thereby masking time trajectories of disease risk. In this study we propose a new idea titled "spatio-temporal kernel density estimation (stKDE)" that employs hybrid kernel (i.e., weight) functions to evaluate the spatio-temporal disease risks. This approach not only can make full use of sample data but also "borrows" information in a particular manner from neighboring points both in space and time via appropriate choice of kernel functions. Monte Carlo simulations show that the proposed method performs substantially better than the traditional (i.e., frequency-based) kernel density estimation (trKDE) which has been used in applied settings while two illustrative examples demonstrate that the proposed approach can yield superior results compared to the popular trKDE approach. In addition, there exist various possibilities for improving and extending this method.
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Affiliation(s)
- Zhijie Zhang
- Department of Geography, Queen's University, Kingston, Ontario, Canada
- Department of Epidemiology, Fudan University, Shanghai, People's Republic of China
| | - Dongmei Chen
- Department of Geography, Queen's University, Kingston, Ontario, Canada
| | - Wenbao Liu
- Department of Geography, Queen's University, Kingston, Ontario, Canada
| | - Jeffrey S. Racine
- Department of Economics, McMaster University, Hamilton, Ontario, Canada
| | - SengHuat Ong
- Department of Mathematical Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Yue Chen
- Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Genming Zhao
- Department of Epidemiology, Fudan University, Shanghai, People's Republic of China
| | - Qingwu Jiang
- Department of Epidemiology, Fudan University, Shanghai, People's Republic of China
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Schistosomiasis in the People's Republic of China: the era of the Three Gorges Dam. Clin Microbiol Rev 2010; 23:442-66. [PMID: 20375361 DOI: 10.1128/cmr.00044-09] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The potential impact of the Three Gorges Dam (TGD) on schistosomiasis transmission in China has invoked considerable global concern. The TGD will result in changes in the water level and silt deposition downstream, favoring the reproduction of Oncomelania snails. Combined with blockages of the Yangtze River's tributaries, these changes will increase the schistosomiasis transmission season within the marshlands along the middle and lower reaches of the Yangtze River. The changing schistosome transmission dynamics necessitate a comprehensive strategy to control schistosomiasis. This review discusses aspects of the epidemiology and transmission of Schistosoma japonicum in China and considers the pathology, clinical outcomes, diagnosis, treatment, immunobiology, and genetics of schistosomiasis japonica together with an overview of current progress in vaccine development, all of which will have an impact on future control efforts. The use of synchronous praziquantel (PZQ) chemotherapy for humans and domestic animals is only temporarily effective, as schistosome reinfection occurs rapidly. Drug delivery requires a substantial infrastructure to regularly cover all parts of an area of endemicity. This makes chemotherapy expensive and, as compliance is often low, a less than satisfactory control option. There is increasing disquiet about the possibility that PZQ-resistant schistosomes will develop. Consequently, as mathematical modeling predicts, vaccine strategies represent an essential component in the future control of schistosomiasis in China. With the inclusion of focal mollusciciding, improvements in sanitation, and health education into the control scenario, China's target of reducing the level of schistosome infection to less than 1% by 2015 may be achievable.
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Identifying high-risk areas of schistosomiasis and associated risk factors in the Poyang Lake region, China. Parasitology 2010; 137:1099-107. [PMID: 20128946 DOI: 10.1017/s003118200999206x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The epidemiology of schistosomiasis japonicum over small areas remains poorly understood, and this is particularly true in China. We aimed to identify high-risk areas for schistosomiasis and associated risk factors in the Poyang Lake region, China. A cross-sectional study was conducted and 60 of 920 persons (6.5%) were found to be infected with Schistosoma japonicum. Locations of households and snail habitats were determined using a hand-held global positioning system. We mapped the data in a geographical information system and used spatial scan statistics to explore clustering of infection, logistic regression and Bayesian geostatistical models to identify risk factors for each individual's infection status and multinomial logistic regression to identify risk factors for living in a cluster area. The risk of schistosomiasis was spatially clustered and higher in fishermen and males, not in persons who lived in close proximity to snail habitats and infected water sources. This study has demonstrated significant spatial variation in the prevalence of schistosomiasis at a small spatial scale. The results suggest that demographic factors (gender, occupation) rather than the distance to infected water are driving human transmission at small-scale spatial levels. Such information can be used to plan locally targeted interventions based on anthelminthic drug administration, snail control and sanitation improvement.
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Malone JB, Yang GJ, Leonardo L, Zhou XN. Implementing a Geospatial Health Data Infrastructure for Control of Asian Schistosomiasis in the People's Republic of China and the Philippines. ADVANCES IN PARASITOLOGY 2010; 73:71-100. [DOI: 10.1016/s0065-308x(10)73004-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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