Abstract
According to the 2015 WHO report, almost half of the world population is exposed to malaria, with the largest number of reported cases in sub-Saharan Africa. Madagascar is one of the countries where malaria is still endemic because of its geographical location. As a matter of fact, the geography and climate of the island gives a specific epidemiological stratification of malaria. There are five malaria epidemiological zones: East, West, South, Highlands and Fringe. The highest incidence is observed on coastal areas, while the lowest incidence is observed on the Central Highlands. This study aims to provide a better understanding of the epidemiology of malaria and to measure the impact of human mobility on transmission from high transmission areas to low transmission areas in order to help better target control actions by public health actors. This study proposes an alternative approach to assess the spatiotemporal dynamics of malaria, quantify the circulation of malaria infection and take into account the mobility of the population to identify the main source and sink areas of malaria. Firstly, through a retrospective analysis of incidence data, this work showed a clear heterogeneity in each stratum, and an increase the Highlands and the Fringe areas. Secondly, regardless of the population density, we have shown that the Highlands and especially the capital of Madagascar, Antananarivo, was a zone at high risk of the importation of malaria. The source areas were mainly in the eastern and the western part of the country. Finally, our field survey highlighted the importance of low inter-district mobility and high intra-district or even intra-communal mobility which should be taken into consideration when assessing the spreading of malaria infection. This study revealed that malaria is very dynamic in Madagascar with a different degree of intensity even if such areas belong to the same stratum. This observation should translate into an adaptation of control strategies. Finally, human mobility plays a leading part in the transmission. At a time when mobile telephony has spread widely in Madagascar, its use to estimate the mobility of populations is becoming a relevant tool to help guide disease control.