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A Vectorial Capacity Product to Monitor Changing Malaria Transmission Potential in Epidemic Regions of Africa

DOI: 10.1155/2012/595948

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Rainfall and temperature are two of the major factors triggering malaria epidemics in warm semi-arid (desert-fringe) and high altitude (highland-fringe) epidemic risk areas. The ability of the mosquitoes to transmit Plasmodium spp. is dependent upon a series of biological features generally referred to as vectorial capacity. In this study, the vectorial capacity model (VCAP) was expanded to include the influence of rainfall and temperature variables on malaria transmission potential. Data from two remote sensing products were used to monitor rainfall and temperature and were integrated into the VCAP model. The expanded model was tested in Eritrea and Madagascar to check the viability of the approach. The analysis of VCAP in relation to rainfall, temperature and malaria incidence data in these regions shows that the expanded VCAP correctly tracks the risk of malaria both in regions where rainfall is the limiting factor and in regions where temperature is the limiting factor. The VCAP maps are currently offered as an experimental resource for testing within Malaria Early Warning applications in epidemic prone regions of sub-Saharan Africa. User feedback is currently being collected in preparation for further evaluation and refinement of the VCAP model. 1. Introduction Malaria is a major public health threat to the African continent and its control is critical to achieving the Millennium Development Goals in this region [1]. Although considerable progress has been made to reduce the malaria burden in sub-Saharan Africa by introducing control measures such as the provision of insecticide-treated mosquito nets, indoor residual spraying, and easier access to effective antimalarial drugs [2], malaria epidemics continue to occur. Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic-prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups [3]. The impact of epidemics could be minimized through prediction, improved prevention through timely vector control, and deployment of appropriate control measures. The implementation of a Malaria Early Warning System enables regional health ministries to focus on epidemiological surveillance and be better prepared to take necessary actions. Rainfall and temperature anomalies are two of the major environmental factors triggering epidemics in warm semi-arid and altitude areas. Increases in epidemics often occur in these regions after excessive rains or increases in temperature [4, 5]. The ability

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