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Objective To assess the quantitative relationship between the distribution of Himalayan marmot and its ecological environment,the terrain,the temperature and the precipitation,using remote sensing and geographic information system in Qinghai province.Methods The distribution of Himalayan marmot was located by Google Earth and ArcGIS software and by using field survey data provided by Chinese Center for Disease Control and Prevention.The corresponding ecological environment of marmot including terrain,temperature and precipitation were derived from the spatial information datasets.All results were processed according to the overlay and statistics analysis using ArcGIS software.Results Seventy-seven point twenty-seven percent(153/198) of Himalayan marmot were distributed in the area of elevation between 3000 and 4000 meters.The number of marmot reached the highest when the slope was between 0 and 17 degrees,and aspect range was between 91 and 270 degrees,180 degree was as south direction.During the period with the maximum temperature of the warmest month of 14.3-17.5 ℃,17.6-20.8 ℃ and 20.9-24.0 ℃,the distribution of marmot reached 95％(186/198) of the total area.Meanwhile,most of the marmot were presented in the area with average precipitation of 46-108 mm.Conclusions A quantitative analysis of appropriate ecological environment of Himalayan marmot in a large scope is carried uul successfully using remote sensing and geographic information system.The study indicates that spatial information technology has important applications in plague prevention and control.
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<p><b>OBJECTIVE</b>To analyze the spatial distribution of highly pathogenic avian influenza (HPAI) and to explore environmental factors associated with HPAI using geographic information system (GIS) techniques in Mainland China.</p><p><b>METHODS</b>Databases were set up using the information of HPAI during epidemics in 2004, and linked to digital maps at provincial and county administrative layers in the country through the ArcGIS 8.3 software. Spatial cluster analyses, spatial statistics analyses and tracking analyses on epidemic situation of HPAI were implemented. Environmental factors associated with HPAI were also analyzed on data related to weather, vegetation and migratory birds etc.</p><p><b>RESULTS</b>Findings from spatial cluster analyses showed that high incidence area was centralized in 113.261 degrees ordm; east longitude and 23. 119 degrees ordm; north latitude with a radius of 1090.52 kilometers (relative risk= 2.646, P value= 0.001). Spatial statistical analyses showed that HPAI took place mainly in capital cities of provinces and surrounding areas as well as in the circumference areas of arterial rivers, lakes and seacoasts. Results also showed that HPAI occurrences were associated with low air temperature, high relative humidity and high air pressure as well as with east & central migration routes of migratory birds. The average normalized difference vegetation index was 0.36 +/- 0.11 in epidemic areas of HPAI.</p><p><b>CONCLUSION</b>HPAI was unrandomly distributed and geographically clustered in China.</p>