Research On Distribution Regulatities Of Oncomelania In Miju River System

[Objectives]To describe and analyze the temporal and spacial distribution characteristics andtheir change rules of Oncomelania in main stream and chief tributary of Miju riversystem by GIS, GPS technology and epidemiological principle and method; and toprovide reasonable suggestion for Oncomelania extermination and diseasesprevention in hill and mountain areas.[Materials]1. Collect data related Oncomelania of140natural villages from24administrativevillages along Miju river systems from2005to2011.2. Collect electronic map （1:50000） of Dali autonomous prefecture.3. Download SRTM-DEM （Digital Elevation Model） data of Yunnan province, mapof Miju river system, topographic map and satellite map.[Methods]1. Build database of geographic information system （GIS）: Input Oncomelania datato excel tables to establish attribute database, then combine it with the longitudeand latitude data of villages and DEM data to establish GIS database.2. The descriptive analysis: Using ArcGIS10.0and Excel2003, describe thetemporal and spacial distribution characteristics of Oncomelania in villages alongMiju river system from2005to2011.3. General statistic analysis: By ArcGIS10.0and Spss16, do statistic analysis to thetemporal and spacial distribution characteristics and distribution rules ofOncomelania in villages along Miju river system.4. Geographic statistic analysis: On the basis of principle of geographic statistics,analyze relevance between the indexes of Oncomelania data and the spacialstructure of Miju river system by ArcGIS10.0, and analyze relevance inside eachindex and each other by ArcGIS10.0.[Results]1. The distribution of Oncomelania along Miju river system was more widely.During2005²011，the areas with Oncomelania were sustained decreasing, thelarger decline is in2005²008. The constituent ratio of the areas withOncomelania in the environment such as fields and trenchs was most large, up to98.27%in2011. The indexes including occurrence of Oncomelania box, average density of living Oncomelania, density of positive Oncomelania, natural infectionrates generally accorded with variation tendency of the areas with Oncomelania.2. The result of spacial analysis indicated that there exited5focal areas of highdensity living Oncomelania: â… Haixihai area of Niujie township; â…¡Miju river areaof Sanying township; â…¢ The south regional of the inlet and outlet of Cibi lake; â…£near the village of Zhongsuo;â…¤near the village of Qingsuo. There werecorrelativity between the density of Oncomelania and the geographic position ofnatural village and river net. There were not discrete clustering phenomenon in therange of0.01⁰.09°（1048.16⁹433.42meters）. The spacial clustering andautocorrelation of the average density of living Oncomelania（2009）, the density ofpositive Oncomelania （2005and2006）, the natural infection rate（2006） isprominant.3. Distance analysis showed that87.86%of natural villages were in the range of600meteres near Miju river,84.05%of the areas with Oncomelania were within thescope of600meters.4. Elevation analysis showed that Oncomelania distributed at an altitude of1966-1992meters or2054-2164meters areas.5. Build an equation with statistic significance Y=-0.287+0.000153X₁（F=10.721，P=0.001，R²=0.072）,Y is the occurrence of Oncomelania box, X₁is elevation.Build the second equation with statistic significance Y=-0.964+0.000503X₁+13.399X₂（F=4.181，P=0.017，R²=0.058）,Y is the densityof living Oncomelania, X₁is elevation, X₂is the distance to Miju river system.The indexes such as density of positive Oncomelania and natural infection ratedidn’t have obvious correlativity with elevation, the distance to the source, thedistance to nozzle in and out of Cibi lake, the distance to estuary.6. Obtained analysis figure of Oncomelania density of the natural village in Mijuriver system, trend surface figure, hot issues figure, buffer figure with four circlesof Miju river system.[Conclusion]1. During2005²011, all indexes of Oncomelania in the village near Miju riversystem had been sustained decreased significantly, and Oncomelania had beeneffectively controlled.2. The key areas of the Oncomelania checking is the irrigation canals and ditches.3. The distribution of Oncomelania has its aggregation,such as the area of â… Haixihaiarea of Niujie township; â…¡Miju river area of Sanying township; â…¢ The southregional of the inlet and outlet of Cibi lake; â…£ near the village of Zhongsuo;â…¤nearthe village of Qingsuo are the key areas of the Oncomelania checking.4. Within600meters of Miju river system is Oncomelania’s main distribution and it is also the key areas of the Oncomelania checking.5. The combination of classical statistical method and geographic statistical methodcan describe the distribution and change of Oncomelania preferably. This will provide abasis for prevention and control of Schistosomiasis and for decision making effectivelyin large scale and scope.