Detection and genetic characterization of arboviruses and other viruses from mosquitoes collected in southeastern and central Senegal, October 2022

The knowledge of the distribution of viruses and their associated mosquito species is still incomplete in Senegal. Additionally, data on the genetic characterization of these viruses are limited. The aim was to update knowledge on the diversity, distribution and genetic relationships of mosquito-associated viruses in Senegal through entomological and molecular surveillance. Mosquitoes were collected in October 2022 across 10 districts in Senegal. Samples were identified morphologically and processed for virome characterization using qRT-PCR and next-generation sequencing. The most common species were Culex cinereus Theobald, 1901, Culex quinquefasciatus Say, 1823, Culex neavei Theobald, 1904, and Culex poicilipes Theobald, 1904 (Diptera: Culicidae). The number of mosquitoes collected varied by habitat and district. We detected 42 isolates of 7 viruses, including Bagaza (BAGV), Barkedji, Sindbis (SINV), Usutu (USUV), Dezidougou, Densovirus and Pestivirus A (PESVA), in 6 mosquito species (Mansonia uniformis, Cx. neavei Theobald, 1901, Anopheles coustani, Cx. cinereus Laveran, 1900, Aedes aegypti Linnaeus, 1762 and Aedes vexans Meigen, 1830) (Diptera: Culicidae). The viruses were mainly detected in mosquitoes collected near ponds (92.9%). BAGV and SINV were detected for the first time in southeastern Senegal. This is also the first association of PESVA with mosquitoes in the field. Phylogenetic analyses revealed that PESVA clustered with strains from Asia and Egypt, BAGV with strains from Senegal and Spain, USUV with strains from Senegal and SINV with strains from Spain and Kenya. This study expands the understanding of mosquito-virus associations in Senegal, revealing new geographic distributions and vectors for several viruses, with implications for arbovirus emergence and surveillance strategies.