Malaria and environment : Search for specific landscape indicators of its distribution in the village of Grande Comore
Résumé
Malaria has long been endemic in the Union of Comoros. Grande Comore has experienced the highest rates of malaria among the Comorian islands for 90 years. Between 2010 and 2016, more than 82% of reported malaria cases were reported to the Grande Comore. Maintaining a high incidence rate of malaria on the island of Grande Comore, unlike the remaining islands, intrigues malaria control leaders in the Union of the Comoros. This study aims at describing the spatial patterns of the epidemiology of malaria and at identifying environmental indicators through a geographical approach in Grande Comore. Monthly cases, as reported by the ?Programme National de lutte Contre le paludisme? (PNLP) in 2016, were geo-referenced in the island of Grande Comore, at two different scales: by health district and villages. Using SPOT 5 satellite images of Grande Comore, we described and classified the land use by an Object-Based Image Analysis (OBIA) method. We used this classification to calculate landscape metrics within 1km, 1.5km and 2km radius of each village (percentage of surface area covered by each land use class, the patch and edge densities). We realized statistical and spatial analyses to show the relationships between malaria and environmental information. We applied the Global Moran's I and the Anselin Local Moran's I to test spatial correlation of malaria incidence between villages. In 2016, 1,372 malaria cases were recorded in 116 villages. The average incidence of all the villages was 301 cases per 100,000 inhabitants. We observed significant and positive correlation between malaria incidence with grassland (RR=0.03, p