Spatially targeting <it>Culex quinquefasciatus </it>aquatic habitats on modified land cover for implementing an Integrated Vector Management (IVM) program in three villages within the Mwea Rice Scheme, Kenya

• Main Authors: Githure John, Funes Jose, Muriu Simon M, Mwangangi Joseph M, Muturi Ephantus J, Shililu Josephat, Jacob Benjamin G, Regens James L, Novak Robert J
• Format: Article
• Language: English
• Published: BMC 2006-05-01
• Series: International Journal of Health Geographics
• Online Access: http://www.ij-healthgeographics.com/content/5/1/18

<p>Abstract</p> <p>Background</p> <p>Continuous land cover modification is an important part of spatial epidemiology because it can help identify environmental factors and <it>Culex </it>mosquitoes associated with arbovirus transmission and thus guide control intervention. The aim of this study was to determine whether remotely sensed data could be used to identify rice-related <it>Culex quinquefasciatus </it>breeding habitats in three rice-villages within the Mwea Rice Scheme, Kenya. We examined whether a land use land cover (LULC) classification based on two scenes, IKONOS at 4 m and Landsat Thematic Mapper at 30 m could be used to map different land uses and rice planted at different times (cohorts), and to infer which LULC change were correlated to high density <it>Cx. quinquefasciatus </it>aquatic habitats. We performed a maximum likelihood unsupervised classification in Erdas <it>Imagine </it>V8.7^®and generated three land cover classifications, rice field, fallow and built environment. Differentially corrected global positioning systems (DGPS) ground coordinates of <it>Cx. quinquefasciatus </it>aquatic habitats were overlaid onto the LULC maps generated in ArcInfo 9.1^®. Grid cells were stratified by levels of irrigation (well-irrigated and poorly-irrigated) and varied according to size of the paddy.</p> <p>Results</p> <p>Total LULC change between 1988–2005 was 42.1 % in Kangichiri, 52.8 % in Kiuria and and 50.6 % Rurumi. The most frequent LULC changes was rice field to fallow and fallow to rice field. The proportion of aquatic habitats positive for <it>Culex </it>larvae in LULC change sites was 77.5% in Kangichiri, 72.9% in Kiuria and 73.7% in Rurumi. Poorly – irrigated grid cells displayed 63.3% of aquatic habitats among all LULC change sites.</p> <p>Conclusion</p> <p>We demonstrate that optical remote sensing can identify rice cultivation LULC sites associated with high <it>Culex </it>oviposition. We argue that the regions of higher <it>Culex </it>abundance based on oviposition surveillance sites reflect underlying differences in abundance of larval habitats which is where limited control resources could be concentrated to reduce vector larval abundance.</p>