title: Long-term impact of the World Bank Loan Project for schistosomiasis control: a comparison of the spatial distribution of schistosomiasis risk in China.
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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Fudan University, Shanghai, People's Republic of China. epistat@gmail.com
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Zhang
authors.forename: Rong
authors.initials: R
authors.lastname: Zhu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Ward
authors.forename: Wanghong
authors.initials: W
authors.lastname: Xu
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.forename: Jiagang
authors.initials: J
authors.lastname: Guo
authors.forename: Fei
authors.initials: F
authors.lastname: Zhao
authors.forename: Qingwu
authors.initials: Q
authors.lastname: Jiang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003140:Communicable Disease Control / Q000191:economics / Q000379:methods*; D019353:Endemic Diseases; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D018570:Risk Assessment; D012552:Schistosomiasis / Q000453:epidemiology* / Q000517:prevention & control*; D019371:Topography, Medical / Q000191:economics / Q000706:statistics & numerical data*; D014480:United Nations; D055815:Young Adult