Integrated vector and arbovirus surveillance in Cyprus: first reports of Usutu virus and Culex pipiens bioform diversity highlight potential for zoonotic arbovirus transmission

Abstract Background Anthropogenic pressures, including urbanisation, globalisation and climate change, have facilitated an increased risk for emergence or re-emergence of mosquito-borne diseases into regions such as the Eastern Mediterranean and Middle East. Cyprus is a major stop-over site for migratory birds and has previously experienced outbreaks of West Nile virus (WNV). The island has native mosquito vector populations; however, it has also seen the recent establishment of invasive Aedes albopictus and Ae. aegypti mosquitoes. Given the dynamic climatic conditions and the shifting ecological and epidemiological landscapes in the region, the need for routine vector and pathogen surveillance has never been more critical. Methods Herein, we present the results from localised adult mosquito surveillance that were conducted in two cities of Cyprus between 2019 and 2022. Mosquito taxa were identified through morphological analysis, and molecular techniques were used to further characterise the Culex pipiens bioforms. Engorged mosquito midguts were analysed to determine host blood meals. Metagenomic next-generation sequencing was employed to screen mosquito pools for arboviruses. Results Our results provide the first report of Usutu virus in Cx. pipiens mosquitoes in Cyprus. Blood meal analysis identified multiple vertebrate hosts, including Cetti’s warbler, a bird species previously reported to be seropositive for WNV on the island. Additionally, we report the presence of both Cx. pipiens pipiens and Cx. pipiens molestus, an ornithophilic and a mammophilic bioform, respectively, as well as their hybrids. Conclusions Our findings highlight the urgent need for enhanced mosquito surveillance strategies where mosquito populations will be regularly screened for pathogens to mitigate emerging risks of arbovirus transmission in Cyprus. Graphical abstract