| Schistosomiasis is a disease having a close relationship with geographic environment factors. The distribution of schistosome is depended on the snail's distribution , the single intermediate host of schistosomiasis.The study is to explore the relationship between the climate factors (including temperature, rainfall and sunshine time) and the density of snail in army station at Jiangning County . Investigating the snail density and the climate data supervised by Jiangning weather station from 1989 to 2000, including the average temperature, rainfall and sunshine time every month, the correlation of the snail density and these climate data was explored using the correlation analysis and multivariable liner regression. This study indicate that the distribution of snail was influenced by the climate factors and the difference climate factors play variable roles in different micro-environment at which snail survive. Results indicated that the snail density of marshland correlated positively with the average temperature of January (P <0.05) and the snail density of mountain related negatively to the sunshine time of March and October (P <0.05). By the multivariable regression , we established the equation for marshland: r=-1.752+0.392f;+0.274/7 (R2=0.724), and for mountain: 7=0.707-0.00375^ (R2=0.565). (Y is the snail density , /yand t2 are the average temperature of January and February every year. $3 is the sunshine tune of March every year).For farther analysising the relationship between the geographic environment factors with the distribution of snail , the geographic information system (GIS) for snail's distribution in army station at Jiangning country was established and the preliminary space analysis was carried out . First the cluster analysis wereperformed based on the density of snail .The analysis demonstrated that 2 significant spatial clusters for alive snail in marshland and 4 in mountain areas. The significant spatial clusters of snail indicated that there are some potential factors suitable for the survival of snails at these areas . The study also found that the soil type of different endemic area of snail is different. The marshland-model areas' is fluvo-aquic soil mostly , and on the other hand ,the mountain-model areas' is diversify . when the layer of the spots of mountain-model snail habitat was combined with the aspect map of Jiangning country, the result shows that the most of the sports locate at the areas with enough sunshine .which direct at east, south or are flat. Moreover, the study of distances of the spots of snail habitat to waterside indicates that most of the of spots of snail habitat lie within the distance of 500 meters to waterside (85.7% ) and the snail density of the spots within 100 meters to waterside is significantly high than the spot's which exceed 500 meters to waterside (P < 0.05 ) .This study devoted to synthetically analysis the relationship between the environment factors and the distribution of snail ,and the establishment of GIS of snail's distribution at Jiangning country is also helpful for production of the predicted model and map of schistosomiasis, which is very useful for the further research of the risk factors and for carrying out of the anti-snail strategies. |
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