Objective To evaluate the impact of the project diverting the Yangtze River water to the Northern Jiangsu on transmission towards the north of Oncomelania hupensis snails, in order to provide the scientific basis for the South-North Water Diversion Project (east route). Methods The running situation of the water diversion project, the data on hydrology of the waterway and the distribution of snails and schistosomiasis were investigated with the methods of epidemiology、hydrology and field test. Results There was no significant correlation between the region of waterhead and water supply on the change of snail areas. There was no significant correlation between the snail areas of the region of water supply and the volume of water diversion, either. The snail habitat was stable at the Gaoyou segment along the Grand Canal. The snail habitat in the natural place of the north of 33?15′ north latitude on the east route has not been discovered yet. Conclusion There is no sign of transmission towards north on the snail habitat at the Gaoyou segment along the Grand Canal since the project was constructed in 1961. There is no evidence that the project leads to the spread of snails and schistosomiasis, either.

Objective To design the Internet geographic information system (GIS) on schistosomiasis of Jiangsu Province using the technology of WebGIS. Methods Based on the GIS database of schistosomiasis, the active model of WebGIS on schistosomiasis was developed with the software of ArcIMS. Results The WebGIS of schistosomiasis has been developed and it has been running on the intranet of Jiangsu Institute of Parasitic Diseases. The system would manage the geographic database and attribute material database, and it would provide the function of query, display, analysis, statistics, export, etc. Conclusion It is feasible to design the WebGIS of schistosomiasis, which provides the basics of developing the Management Decision Systems of Schistosomiasis of Jiangsu Province.

Objective To observe hibernation phenomena of Oncomelanai hupensis and explore the way of inducing the hibernation in laboratory. \ Methods\ Snails, O\^hupensis hupensis, were collected from marshland of Jiangsu. The snail hibernation was induced by the way of cultivation at a mimic natural environment in the laboratory with gradually changing temperature. The amount of oxygen consumed by snails was tested by iodine titration, and their hibernation was tested by pin puncture followed by warm water. \ Results \ There was no significant difference on the rate of snail \{hibernation\} when the temperature was reduced by 1 ℃ per 24 hrs and by 1 ℃ per 48 hrs. The hibernation rate \{increased\} with the decreasing temperature. There was a significant regression relationship between hibernation rate and temperature with R\+2=0\^967 (F=207\^72, P

Objective To explore the aestivation and lethal hyperthermy temperature of Oncomelania hupensis in summer,which is one of important ecology indexes,in order to understand the potential impact of global warming on the distribution of Oncomelania snail in mainland China. Methods Oncomelania hupensis hupensis snails were collected from the marshland region in Jiangsu Province and the aestivation and lethal hyperthermy temperature were examined by increasing temperature gradually in laboratory. Results The lethal hyperthermy temperatures of 50% Oncomelamia snails in dry and wet environment was 40.01℃ ( 95% of confidence interval from 39.76-40.27℃) and 42.13℃( 95% of confidence interval from 41.59-42.68℃), respectively. The logistic regression equations between temperature and mortality were d=101/(1+e 61.402269-1.535058X) (F=69.997,P

Objective To determine the effective accumulated temperature of Oncomelania hu-pensis during the period of development of generations in the natural environment. Methods The snails, Oncumelania hupensis, were raised in natural breeding site, the developing duration and accumulated temperature for .snails' development from eggs to adult that began to lay eggs were estimated based on the formula T=?(Ti-C). Results The average developing duration was (334.22?7. 52) days, average accumulated temperature was (5 821.38?70.05) day degree, and average effective accumulated temperature was (3 846.28?32. 59) day degree. Conclusion The method to estimate the effective accumulated temperature is quite accuracy, which provides theoretical parameters in developing the prediction model on transmission of schistosomiasis japonica affected by weather warming.

Objective To evaluate the molluscicidal effect and the using value of qiangluocide powder by dusting in the fields. Methods The two different ways of dusting with qiangluocide and spraying with luomiecide for controlling snails were compared in the fields, and the cost-effectiveness was analysed. Results The corrected mortalities and the reduced rates for density of snails were 88.48%, 96.26%, 96.96%, 95.67%, and 87.58%, 95.40%, 96.14%, 96.67%, respectively, on the marshland in Longtan, Nanjing, 73. 65% , 98. 31% , 99. 22% , 99. 26% and 69. 30% , 98.14%, 98.84%, 98. 60% , respectively, on the marshland in Yizheng, Yangzhou, on 1 d, 3d, 7 d, 15 d after dusting with qiangliocide power; and those on 1d, 3d, 7d, 15d after the spraying with luomiecide were 69.15%, 88.01%, 86.46%, 85.56% and 75.27%, 84.99%, 87.50%, 87.96% on the marshland in Longtan, Nanjing, 18.70%, 63.11%, 1.25%, 12.60% and 34. 88% , 89. 02% , 45.37% , 46. 59% , respectively, on the marshland in Yizheng, Yangzhou. The st of dusting with qiangluocide powder was 0. 20 yuan/m2, and that of spraying with luomiecide as 0. 21 yuan/m2 for snail control in the fields. The costs of reduced one percentage for the cor rected mortalities and the density of snail were 6. 27-10. 07 yuan and 6. 21-10. 14 yuan, respectively, on 15 d after dusting with qiangluocide power and those on 15 d after spraying with luomiecide were 7. 36-83. 33 yuan and 7. 16-22. 54 yuan , respectively. Conclusion The dusting with qiangluocide powder is a promising new formulation, which is suitable for the areas without water resource and possessed of high effectiveness against snails. The method ofdusting with qian-gluocide powder for controlling snails is simple, convenient, cheap and easy to be carried out for the inspection and quality control.

Objective To explore the spatial distribution of schistosomiasis cases and Oncomelania snails in the provinces of Jiangsu, Anhui and Jiangxi with the assistance of geographic information systems (GIS). Methods Epidemiological data of schistosomiasis in recent 20 years were collected, and the relevant GIS databases were established. The spatial autocorrelation analysis was carried out with ArcView 3\^x, S\|Plus, and Spatial Statistics software. Results Except for schistosomiasis cases in Jiangsu, the spatial distribution of schistosomiasis cases and Oncomelania snails in the three provinces were fitted to the spatial autocorrelation at a certain degree. Generally the autocorrelation coefficients (Moran′s I) in Oncomelania snails were higher than that in schistosomiasis cases. Conclusion Spatial autocorrelation analysis can be used to estimate the value of one variable in different spatial position, and it is a good way to find out the spatial cluster distribution in different stages.

Objective To study the expression of nitric oxide synthase (NOS)mRNA in the gonad of Oncamelania hu-pensis in different temperature. Methods The snails were cultured at temperature of 0℃ , 15 ℃and 25℃for 1 month. The total RNA of each group was extracted with the RNA extraction kit. A pair of degenerate primers was designed from conserved regions of mammalian NOSs, and the expression of NOS mRNA in the gonad was measured by means of reverse transcription polymerase chain reaction (RT-PCR). Results The target genes of NOS were detected in the gonad of snails. The level of expression of snail NOS mRNA in 25℃ group and 0℃group was significantly higher than that in the control group( P 0.05). Conclusion The designation of primers of the snails was validated. The impact of temperature on the expression of snail NOS mRNA was determined, which suggested that NO plays an important role in the physiological and pathological modulation.

Objective To study the impact of environmental temperature on the development of Schistosoma japonicum larvae within the Oncomelania hupensis. Methods Oncomelania snails, collected from the field and free of S. japonicum infection, were exposed to miracidiae of S. japonicum in a ratio of 1∶20 and raised at 30 ℃, 27 ℃, 24 ℃, 21 ℃ and 18 ℃, respectively. The prepatent period of larvae within the Oncomelania hupensis and the developmental velocity were determined, of which the relationship with the temperature was analysed. Results The average prepatent period of cercariae in snail was (128.89?16.05) d,(95.00?21.03) d,(71.93?12.74) d and (62.74?14.19) d at 21 ℃, 24 ℃, 27 ℃, 30 ℃, respectively. The regression formulation between prepatent period and temperature was y =730.68x -0.8918 (r=0.9976, P

Objective To understand the impact of environmental temperature on the infection of miracidia of Schistosoma japonicum to Oncomelania snails, and to estimate the lowest critical temperature for infection of snails with miracidia. Methods Oncomelania snails free of S.japonicum were collected from field,and exposed to miracidia at the ratio of 1∶20 under the different temperatures, such as 5,6,8,10,15,20℃.Snails were dissected to check if infected after exposured and kept in 25℃ for another 70 days. Results The infection rate of snails were 0,0.92,1.43,2.40,8.96,17.39% under the temperature of 5,6,8,10,15,20℃, respectively. The relationship between snail infection rate and temperature for infection was showed in the regression formulation of y=0.0622x 2-0.4035x+0.6703 (r=0.9988,P