Sudhakar S, Srinivas T, Palit A, Kar S K, Battacharya S K
National Remote Sensing Agency, Department of Space, Hyderabad, India.
J Vector Borne Dis. 2006 Sep;43(3):115-22.
BACKGROUND & OBJECTIVES: The kala-azar fever (Visceral leishmaniasis) is continuing unabated in India for over a century, now being largely confined to the eastern part of India mainly in Bihar state and to some extent in its bordering states like West Bengal and Uttar Pradesh. Two study sites namely Patepur block in Vaishali district with high endemicity in northern part and Lohardagga block in Lohardagga district with absolute non-endemicity in southern part of Bihar were selected for the study with the following objectives : (i) to study the macro-ecosystem in relation to distribution of vector -Phlebotomus argentipes; (ii) to identify/map the risk prone areas or villages in a block for quick remedial measures; and (iii) to make use of satellite remote sensing and GIS to demonstrate the utility for rapid assessment of landuse/landcover and their relation with the incidence of kalaazar leading to the mapping of risk prone areas.
Indian Remote Sensing (IRS)-1D LISS III satellite data for the periods of March and November 2000 were analysed in Silicon graphic image processing system using ERDAS software. False color composites (FCC) were generated and landuse/landcover was assessed using Maximum likelihood supervised classification techniques based on ground truth training sets. During the study the GIS functions are used to quantify the remotely sensed landscape proportions of 5 km2 buffer surrounding each known group of villages of high occurrence of sandflies in endemic and nonendemic study sites. Instead of traditional ground based survey methods to vector surveillance, the present study used a combination of remote sensing (RS) and geographical information system (GIS) approach to develop landscape predictors of sandfly abundance-an indicator of human vector contact and as a measure of risk prone areas.
Statistical analysis using the remotely sensed landscape variables showed that rural villages surrounded by higher proportion of transitional swamps with soft stemmed edible plants and banana, sugarcane plantations had higher sandfly abundance and would, therefore, be at higher risk prone areas for man-vector contact.
INTERPRETATION & CONCLUSION: The present study clearly brought out the usefulness of satellite remote sensing technology in generating the crucial information on spatial distribution of landuse/landcover classes with special emphasis on indicator landcover classes thereby helping in prioritising the area to identify risk prone areas of kala-azar through GIS application tools.
黑热病（内脏利什曼病）在印度持续肆虐已达一个多世纪，目前主要集中在印度东部，主要是比哈尔邦，在一定程度上也存在于其接壤的邦，如西孟加拉邦和北方邦。本研究选取了比哈尔邦北部高流行率的瓦伊沙利区帕特布尔街区和南部绝对无流行的洛哈达加区洛哈达加街区这两个研究地点，目标如下：（i）研究与媒介白蛉分布相关的宏观生态系统；（ii）识别/绘制街区内易发生风险的区域或村庄，以便迅速采取补救措施；（iii）利用卫星遥感和地理信息系统展示其在快速评估土地利用/土地覆盖及其与黑热病发病率的关系以绘制易发生风险区域方面的效用。
在使用ERDAS软件的硅图形图像处理系统中分析了2000年3月和11月的印度遥感（IRS）-1D LISS III卫星数据。生成了假彩色合成图像（FCC），并基于地面真值训练集使用最大似然监督分类技术评估了土地利用/土地覆盖情况。在研究过程中，地理信息系统功能用于量化流行和非流行研究地点中每个已知白蛉高发村庄群周围5平方公里缓冲区的遥感景观比例。本研究并非采用传统的地面媒介监测调查方法，而是使用遥感（RS）和地理信息系统（GIS）方法相结合来开发白蛉丰度的景观预测指标——人类与媒介接触的一个指标，也是易发生风险区域的一种衡量标准。
使用遥感景观变量进行的统计分析表明，被比例更高的过渡性沼泽包围、有软茎食用植物以及香蕉、甘蔗种植园的乡村白蛉丰度更高，因此，这些区域人类与媒介接触的风险也更高。
本研究清楚地表明了卫星遥感技术在生成关于土地利用/土地覆盖类别空间分布的关键信息方面的有用性，特别强调了指示性土地覆盖类别，从而有助于通过地理信息系统应用工具确定优先区域，以识别黑热病的易发生风险区域。
