The South-to-North Water Diversion Project: effect of the water diversion pattern on transmission of Oncomelania hupensis, the intermediate host of Schistosoma japonicum in China

Abstract

BackgroundThe South-to-North Water Diversion Project (SNWDP) is the largest national water conservancy project in China. However, the Eastern Route Project (ERP) of SNWDP will refer to the habitats of Oncomelania hupensis, the intermediate host of Schistosoma japonicum. The present study was aimed at investigating the effects of some factors relating to the water diversion pattern on the spread north of O. hupensis and transmission of S. japonicum.MethodsMarked snails were attached to the floating debris, and then placed on the water surface, the passage of snails through water pumps was observed. Some marked living adult snails were placed under water in the 5 spots, 15, 30, 60, 90 and 120 days later, their survival and transfer under water were investigated. 2, 4, 8, 16, 32, 64 and 128 juvenile snails, with a male: female ratio of about 1, were caged, 1 year later, their reproductions were calculated.ResultsThe snails attached on the floating debris at 100-, 50- and 20-cm-distance from the inlet pipe of the big pump (with a diameter of 80 cm), could be absorbed into the pumps, with passing rates of 2.45%, 3.93% and 43.46%, respectively, compared with 72.07% and 91.00% for the snails at 20 cm and 10 cm-distance from the inlet pipe of the small pump (with a diameter of 20 cm). A total of 36,600 marked living snails were put into 5 ponds and ditches, with the water depths of 1-1.6 m, 15-120 days later, no marked ones were found along the ponds and ditches or in the straw packages. The juvenile snails did not reproduce until their density reached up to 8 snails (ratio of male: female of 1)/0.16 m2.ConclusionsDuring the construction of ERP of SNWDP, the risk of northward spread of schistosomiasis japonica will be decreased or eliminated as long as long-term reliable interventions for snail control are implemented.

Novel DGT method with tri-metal oxide adsorbent for in situ spatiotemporal flux measurement of fluoride in waters and sediments

“…1); a national 245 scheme that aims to deliver water to the drought prone regions in Northern China, by 246 redirecting supplies from the southern watersheds (Liang et al, 2012).…”

The influence of natural factors on the spatio-temporal distribution of Oncomelania hupensis

“…However, in this study, the space-time differences in the effect that NDVI had on snails were not caused by spatio-temporal variability itself. Based on this situation, we should consider the influence of not only other natural factors but also changes in the local environment related to snail survival caused by human activities (Liang et al, 2012;Xie et al, 2014). For example, the impoundment of the Three Gorges project and the South to North Water Diversion Project have changed the wetland pattern of Dongting Lake in recent years, thereby affecting the distributions of snails there (Hu et al, 2015a,b;Liu et al, 2016).…”

Opportunities and challenges of interbasin water transfers: a literature review with bibliometric analysis

“…Its total annual water diversion capacity of three routes would be 44.8 billion m 3 (Zhang 2009). This vast project led to many multi-disciplinary studies, such as those on construction management of the project (Liu et al 2006;Zhong et al 2005), the environmental geology of its Middle Route Project (Wang and Ma 1999), the protection of cultural relics along its Middle Route (Shang et al 2003), water conservation and water purification , regional water security (Chen et al 2013a, b), impact of the project on groundwater resources , pricing and water resource allocation scheme and policy for the project (Chen et al 2013a, b;Jia et al 2013), and the effect on transmission of Oncomelania hupensis, the intermediate host of Schistosoma japonicum in China (Liang et al 2012;Wang et al 2009). The risk of water pollution in its water source areas and main canals is the main concern about the South-to-North Water Transfer/Diversion Project (Shen et al 2015;Tang et al 2014;Xie et al 2011).…”