Spatial heterogeneity and temporal evolution of malaria transmission risk in Dakar, Senegal, according to remotely sensed environmental data

Malaria Journal

Research

Cécile Vignolles¹  Libasse Gadiaga²  Abdoulaye Gaye²  Cheikh Sokhna²  Jean-François Trape²  Jean-Pierre Lacaux³  Frédéric Pagès⁴  Christophe Rogier⁵  Vanessa Machault⁶ 

[1] Centre National d'Etudes Spatiales, Service Applications et Valorisation, 18 avenue Edouard Belin, 31401, Toulouse Cedex 9, France;Institut de Recherche pour le Développement, UMR198 "Paludisme et maladies émergentes en Afrique de l'Ouest: détection, épidémiologie et lutte"/Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes - URMITE, Route des Pères Maristes, BP 1386, 18524, Dakar, Sénégal;Observatoire Midi-Pyrénées, Université Paul Sabatier, 14 avenue Edouard Belin, 31400, Toulouse, France;Unité d'entomologie médicale, Equipe 7 "Maladies émergentes et moustiques"/Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes - URMITE - UMR6236, Institut de Recherche Biomédicale des Armées, Allée du Médecin colonel Jamot, BP60109, Parc du Pharo, 13262, Marseille cedex 07, France;Unité de recherche en biologie et épidémiologie parasitaires, Equipe 7 "Maladies émergentes et moustiques"/Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes - URMITE - UMR6236, Institut de Recherche Biomédicale des Armées, Allée du Médecin colonel Jamot, Parc du Pharo, BP60109, 13262, Marseille cedex 07, France;Unité de recherche en biologie et épidémiologie parasitaires, Equipe 7 "Maladies émergentes et moustiques"/Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes - URMITE - UMR6236, Institut de Recherche Biomédicale des Armées, Allée du Médecin colonel Jamot, Parc du Pharo, BP60109, 13262, Marseille cedex 07, France;Unité d'entomologie médicale, Equipe 7 "Maladies émergentes et moustiques"/Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes - URMITE - UMR6236, Institut de Recherche Biomédicale des Armées, Allée du Médecin colonel Jamot, BP60109, Parc du Pharo, 13262, Marseille cedex 07, France;Centre National d'Etudes Spatiales, Service Applications et Valorisation, 18 avenue Edouard Belin, 31401, Toulouse Cedex 9, France;Observatoire Midi-Pyrénées, Université Paul Sabatier, 14 avenue Edouard Belin, 31400, Toulouse, France;

关键词: Malaria;    Geographic Information System;    Malaria Transmission;    Malaria Risk;    Human Landing Catch;   

DOI  :  10.1186/1475-2875-9-252

 received in 2010-05-21, accepted in 2010-09-03,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundThe United Nations forecasts that by 2050, more than 60% of the African population will live in cities. Thus, urban malaria is considered an important emerging health problem in that continent. Remote sensing (RS) and geographic information systems (GIS) are useful tools for addressing the challenge of assessing, understanding and spatially focusing malaria control activities. The objectives of the present study were to use high spatial resolution SPOT (Satellite Pour l'Observation de la Terre) satellite images to identify some urban environmental factors in Dakar associated with Anopheles arabiensis densities, to assess the persistence of these associations and to describe spatial changes in at-risk environments using a decadal time scale.MethodsTwo SPOT images from the 1996 and 2007 rainy seasons in Dakar were processed to extract environmental factors, using supervised classification of land use and land cover, and a calculation of NDVI (Normalized Difference Vegetation Index) and distance to vegetation. Linear regressions were fitted to identify the ecological factors associated with An. arabiensis aggressiveness measured in 1994-97 in the South and centre districts of Dakar. Risk maps for populated areas were computed and compared for 1996 and 2007 using the results of the statistical models.ResultsAlmost 60% of the variability in anopheline aggressiveness measured in 1994-97 was explained with only one variable: the built-up area in a 300-m radius buffer around the catching points. This association remained stable between 1996 and 2007. Risk maps were drawn by inverting the statistical association. The total increase of the built-up areas in Dakar was about 30% between 1996 and 2007. In proportion to the total population of the city, the population at high risk for malaria fell from 32% to 20%, whereas the low-risk population rose from 29 to 41%.ConclusionsEnvironmental data retrieved from high spatial resolution SPOT satellite images were associated with An. arabiensis densities in Dakar urban setting, which allowed to generate malaria transmission risk maps. The evolution of the risk was quantified, and the results indicated there are benefits of urbanization in Dakar, since the proportion of the low risk population increased while urbanization progressed.

【 授权许可】

CC BY   
© Machault et al; licensee BioMed Central Ltd. 2010