Detection and monitoring of mosquito flaviviruses in Spain between 2001 and 2005

Between the years 2001 and 2005, a total of 72,895 female mosquitoes were trapped during their season of abundance, and analyzed. They were sorted into 4,723 pools belonging to 20 Culicidae species from the Anopheles, Aedes, Ochlerotatus, Culex, Culiseta, Coquillettidia, and Uranotaenia genera. The aim was to detect arboviral RNA directly from mosquito homogenates for the genera Alphavirus, Flavivirus, and Phlebovirus. The study formed part of general arbovirus transmission research in four of the most important wetlands in Spain; in the provinces of Girona, Barcelona, Tarragona, and Huelva. The mosquitoes were collected using human bait, CO(2) traps, or light traps, and they were pooled according to date of collection, location, and species. No arboviral RNA from known pathogenic arboviruses was found. However, 111 pools tested positive for unknown mosquito Flavivirus, the only genus detected. The Flavivirus sequences identified were different from all known Flavivirus mosquito viruses, but very close to Kamiti River virus or cell fusing agent virus. The maximum likelihood estimation infection rate (MLE) was calculated for all regions and species. Aedes albopictus had the highest MLE at 47.14, followed by Ae. vexans with 43.67 (over the entire area). These species were followed by Culiseta annulata, with 36.00. The most common species, Ochlerotatus caspius and Culex pipiens, had low MLE values-0.94 and 0.38, respectively-over the area as a whole.