Abstract
Vector diseases represent a threat on the islands in the Indian Ocean with the emergence and re-emergence of viral pathologies, as show the recent epidemics of arbovirus disease that have touched them. Little recent information exists to enlighten the local dynamics of the virus and identify vector species and reservoirs. This project will be concentrated to the island of Madagascar, an island characterized by a strong endemic biodiversity, contrasting climate conditions and important alterations of habitats due to growing anthropogenic activities. Ancient as well as recent events of epidemics of arbovirus disease have affected human populations. We will analyze three arbovirus diseases: the Chikungunya virus, the Dengue-fever and the Rift Valley fever, which illustrate the cases of pre-emergence, sporadic epidemics and endemic diseases in mankind. We will study the dispersal and the competences of different species of vector mosquitoes linked with the various examined viruses. We will evaluate the role of lemurs, the only non-human primates present on the island, as potential reservoirs species. In Africa, Simian primates constitute important reservoirs for these viruses. It is conceivable that lemurs, being prosimian primates, might fill this role of reservoir species. This hypothesis deserves to be explored since earlier positive serology studies show upon a potentially frequent contact between the lemurs and these viruses. The project aims to characterize the dynamic of interactions between mosquito communities, lemurs and these three arbovirus diseases, and the spatial-temporal variability of this dynamic with the environmental conditions. Programmed for three years, our study will be carried out in three regions that are characterized by an irregular rainfall pattern (moist to dry). Within each region, habitats differing by their anthropogenic level will be sampled at regular time intervals. The issue will be to, through a multidisciplinary approach associating population biologists, veterinaries, bacteriologists, virologists, entomologists, primatologists, and biometricians: - Characterize the mosquito species present in each region - Evaluate the vector competence of different species in relation with the associated bacterial communities - Identify the infection pattern through serology of different species composing the lemur communities - Determine the major risk factors linked to the behaviour of lemur species and to their probability of encountering different vector species, and their adjustment according to the environment (forest and urban environments in three regions, more or less moist) - Conduct a phylogenetic analysis of circulating viruses using variable markers, among vectors as well as among lemurs - Offer alternative control methods and / or complementary methods for chemical control - Following the results, draw up human risk maps in relation to habitats
France