Objective To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. Methods A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area , and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situa?tions of various water levels,a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. Results The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m,and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1,vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m,one transverse ditch was efficient. Otherwise,more transverse ditches should be set with the intervals of 300 m. Conclusions The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches,vertical ditch and levee toe will en?sure the effects and security of the project.

Objective To understand the epidemiological characteristics of patients with advanced schistosomiasis in Hunan Province,so as to provide the evidence for formulating the advanced schistosomiasis prevention strategies and measures. Meth-ods The data of advanced schistosomiasis patients were collected and analyzed retrospectively with the cross section research method and description method in Hunan Province,2012. Results There were 5 722 advanced schistosomiasis patients in Hu-nan Province,and among them,4 112 patients were male(71.86%),and 1 610 were female(28.14%). Totally 5 311 patients came from the schistosomiasis endemic areas(92.82%)and 411 patients from non-schistosomiasis endemic areas(7.18%). The prevalence rate of advanced schistosomiasis was 8.46/10 000. The mean age of advanced schistosomiasis patients was 60.30 ± 11.63 years,and the youngest was 17 years old and the oldest 92 years old. In the age composition of advanced schistosomiasis pa-tients,the greatest number of cases was in the 60-70 years age group (32.72%). There were 3 595 cases of ascites type (62.83%),2107 cases of splenomegaly type(36.82%),11 cases of dwarf type(0.16%),and 11 cases of colon proliferation type (0.35%). Conclusion The prevalence rate of advanced schistosomiasis is relatively stable in Hunan Province,and the age of the patients showed an old aging trend. The salvation of advanced schistosomiasis patients in non-endemic areas should be strength-ened.

Objective To understand the Oncomelania hupensis snail distribution in the working areas of Yangtze River hy?drologic agencies located in the middle and lower reaches of the Yangtze River in 2016,so as to provide the evidence for assess?ing the risk of schistosome infection of hydrological workers and establishing the control strategies. Methods The suspicious en?vironments with O. hupensis snails in the above working areas were selected as study areas,and the snail situation was surveyed by the system sampling method combined with the environmental sampling method. The survey data were collected and analyzed statistically. Results Totally 19 working areas from 17 hydrological agencies were selected as the investigation sites,among which,10 working areas from 9 agencies were found with O. hupensis snail distribution. The constituent ratio of the areas with snails reached to 38.81%of the investigation areas,the occurrence rate of frames with snails was 3.08%,and the average densi?ty of living snails was 0.07/0.1 m2. By comparison,the average density of living snails and occurrence rate of frames with snails in hydrological agencies under the jurisdiction of the Middle Reaches Administrative Bureau were the most serious among three administrative bureaus of the Yangtze River Water Resources Commission. Conclusions There are various degrees of O. hupen?sis breeding in the working areas of hydrological agencies located in the middle and lower reaches of the Yangtze River ,and the hydrological workers are facing with the risk of schistosome infection.

Objective To explore the spatial-temporal characteristics and changing regularities of Schistosoma japonicum in-fections among human from 2004 to 2011. Methods The township level spatial databases of schistosomiasis in Hunan Province from 2004 to 2011 were established,and the related spatial analysis was performed by SPSS 17.0,ArcGIS 10.1 and SaTScan 7.03. Results The schistosome infection rate among human in Hunan Province sharply decreased from 3.0％in 2004 to 0.8％in 2011. However,the rate among residents in parts of some townships in 2011 was still hovering at a higher level (P90=2.12％),and the higher rate was distributed along the Oncomelania hupensis snail ridden areas outside embankment. The auto-correlation analysis showed that the global Moran's I for schistosome infection rate among human was 0.34 to 0.53 from 2004 to 2011,and was higher than the expected value(Z>8.71,P<0.05). The local G statistics indicated that the positive hotspot high-high clustering areas were mainly near the coast of Dongting Lake from 2004 to 2011,and the number of townships with schistosomiasis endemic in the clustering areas reached 30 to 70. The spatial scan analysis showed that the number of townships in the clustering areas ran up to 145 to 183 from 2004 to 2011. Conclusions The schistosome infection rate among human de-creased significantly in Hunan Province from 2004 to 2011. However,the rate in parts of some townships still remains at a com-paratively high level,and there are positive spatial correlation and spatial agglomerations in the schistosome infection rate among human,suggesting that the prevention and control work on schistosomiasis in these areas should be strengthened in the fu-ture.

Objective To understand the dynamic rules of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission controlled or transmission interrupted,so as to provide the evidence for improving schis-tosomiasis control. Methods Wuling District,Xihu District and Linli County were selected and investigated retrospectively to collect the schistosomiasis epidemiological information 10 years before they reached the criteria of transmission controlled and the subsequent years until 2008. A database of retrospective investigation was established for analyzing the trends and rules of changes of the Oncomelania hupensis snail status and infection status of cattle and human. Results In Wuling District,the en-demic situation was declining,and no schistosome infection persons,animals and snails were found after 1974. There was no re-bound until 2008. In Xihu District,the endemic situation reached the criteria of transmission controlled in 1997,and the endem-ic situation was stable. The human infection rate was positively correlated with the area of infection snails(r=0.584,P<0.05). In Linli County,there were no snails,no infected persons and cattle twice,but 2 endemic rebounds,and there were positive corre-lations between the densities of living snails and the infection rates of human and animal during the endemic rebound period. Conclusion The snail status is an important indicator of schistosomiasis endemic rebound. Therefore,the snail control is one of the most important schistosomiasis control measures.