03071nas a2200385   4500000000100000008004100001653001500042653001200057653002900069653002000098653001500118653001900133653002400152653001500176653001900191653001100210653003500221653001600256653001300272653002100285653002300306653002100329653001200350653001800362653001200380653001600392100002000408700001500428700001400443245012200457300001100579490000700590520207400597022001402671       2005                            d10aSimuliidae10aSeasons10aSatellite Communications10aRisk Assessment10aPrevalence10aonchocerciasis10aModels, Theoretical10aIvermectin10aInsect Vectors10aHumans10aGeographic Information Systems10aForecasting10aEthiopia10aEndemic Diseases10aDatabases, Factual10aCluster Analysis10aClimate10aAnthelmintics10aAnimals10aAgriculture1 aGebre-Michael T1 aMalone J B1 aMcNally K00aUse of geographic information systems in the development of prediction models for onchocerciasis control in Ethiopia.  a135-440 v473 a<p>A risk assessment model was developed for onchocerciasis distribution and its control in Ethiopia using Geographic Information System (GIS) methods. GIS data analysis was done to generate 3 separate risk models using selected environmental features of (1) earth observing satellite data on Normalized Difference Vegetation Index (NDVI) and midday Land Surface Temperature (LST) prepared from AVHRR sensor data of the Global land 1-km project for the years 1992 and 1995, (2) FAO agroclimatic databases from the Crop Production System Zone (CPSZ) of the Intergovernmental Authority on Development (IGAD) sub-region of East Africa, and (3) a climate-based forecast index based on the growing degree days (GDD) and water budget concepts. Parasitological data used for the analysis were published and unpublished reports of onchocerciasis surveillance made between 1969 and 2000 in various parts of the country. Analysis of queries based on 1992 and 1995 annual wet and dry season data of the Global land 1-km project resulted in a predictive value of 95.1%, 94.0% and 96.3%, respectively, using data values extracted from buffers centered on sites above 5% prevalence. The model based on CPSZ data predicted an endemic area that best fit the distribution of sites over 5% prevalence; the query was based on CPSZ values of average altitude (442-2134 m), annual mean temperature (18-28 degrees C), annual rainfall (822-1980 mm), annual potential evapotranspiration (1264-1938 mm), rain minus potential evapotranspiration (-124 - 792 mm), average NDVI x 100 (2000-5000) and average terrain percent slope (9-34). The climate-based model based on GDD and water-budget predicted high risk to severe risk areas in the western and southwestern parts of the country. All three of the models predicted suitable areas for the transmission of onchocerciasis outside known endemic areas, suggesting the need for ground-based validation and potential application to current community-directed treatment programs with ivermectin (CDTI) for control of onchocerciasis in Ethiopia.</p>
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