A SPATIAL CLUSTERING APPROACH TO IDENTIFY RISK AREAS OF DENGUE INFECTION AFTER INSECTICIDE SPRAYING

This study aims to demonstrate a spatial clustering approach for identifying risk households of dengue virus infection during the period of insecticide spraying-ultra low volume (ULV). All households located within 100 m radius of spraying area were recorded with geographic coordinates and divide into three groups of spraying (unsprayed, only outdoor and indoor plus outdoor sprayed house). A total of 45 households with geographic coordinates, were randomly selected to monitor ovitrap index, the percentage of positive ovitraps and the number of eggs per trap, in pre-and post-ULV spraying. Application of spatial analyst tools and spatial statistics tools in ArcGIS 10.1 were used to determine mosquito density and identify risk households using ovitrap index. The prediction maps of Aedes aegypti vector abundance were illustrated by kriging technique. Base on the results, the cluster of Ae. aegypti populations were detected on four day after the spraying. This finding shows the significant spatial pattern of dengue vector populations which may cause high risk areas of dengue virus infection after insecticide treatment. This methodological framework could be used for improving the strategy of dengue vector and outbreak control. The spatial association between dengue vector and the coverage of space spraying requires further study.