Anticipating Culex-borne DISease Emergences in the MEDiterranean basin: improved knowledge on the circulation dynamic and transmission of Culex-transmitted arboviruses.

Arboviruses are responsible for zoonoses that originally operate in a wild cycle involving animals and zoophilic vectors. Human infections occur via direct spillovers from enzootic cycles, and transmission from animals to humans occurs through the bite of anthropo-zoophilic vectors. Traditionally confined to tropical regions, arboviruses, such as West Nile virus (WNV) and Usutu (USUV) virus, are increasingly detected in temperate areas, including countries from the Mediterranean Basin. In recent decades, regions from the Mediterranean basin such as the Maghreb, the Middle-Est region and South Europe have been subjected to repeated incursions of WNV and USUV, both transmitted by Culex pipiens and Culex perexiguus mosquitoes. Whether WNV and USUV circulations in these regions result from repeated introductions of novel virus genotypes by migratory birds, and/or from locally established viral reservoirs, is poorly understood. In addition, how global warming, a major public health issue in this region, could influence the transmission of these two arboviruses is understudied. In the current project, we will investigate the circulation dynamics of WNV and USUV by tracking these viruses in their animal hosts and local vectors. The objectives are to: (i) Determine the seasonal circulation dynamics of Culex spp. and identify the virus taxa in these vectors, (ii) Estimate and compare Culex perexiguus and Culex pipiens vector competence for WNV, USUV (iii) Investigate Culex-borne viruses infections in migratory and native-wild birds using virus RNA and antibodies detections, and (iv) Establish risk mapping and predictive modelling of arboviral transmission in the Mediterranean basin in a context of global warming. Fulfilling these objectives will provide valuable data enabling health authorities to develop evidence-based targeted control strategies and enhance early warning systems for arboviral outbreaks in the concerned countries and the Mediterranean basin.