Mosquito habitats, land use, and malaria risk in Belize from satellite imagery

Satellite imagery of northern Belize is used to examine the relationship between land use and habitats of the malaria vector, the Anopheles mosquito. A land cover classification based on multispectral Systeme Probatoire d'Observation de la Terra (SPOT) and multitemporal Radarsat images identified I I land cover classes, including agricultural, forest, and marsh types. Two of the land cover types, Typha domingensis marsh and flooded forest, are habitats of immature Anopheles vestitipennis, and one, Eleocharis spp. marsh, is the habitat for immature Anopheles albimanus. Geographic information systems (GIS) analyses of land cover demonstrate that the amount of Typha domingensis in a marsh is positively correlated with the amount of agricultural land in the adjacent upland and negatively correlated with the amount of adjacent forest. This finding, coupled with field studies documenting higher soil phosphorus in wetlands adjacent to agricultural fields, supports the hypothesis that nutrient runoff is the cause of higher densities of Typha domingensis in marshes adjacent to fields in northern Belize. Thus, agricultural activities can potentially increase Anopheles vestitipennis habitat and thereby increase malaria risk across a broad region where Anopheles vestitipennis is a malaria vector.