Abstract / Summary
West Nile virus (WNV) is a mosquito-borne zoonotic flavivirus with increasing relevance in Europe, posing a significant risk to both human and equine health. This study aimed to investigate the presence of flaviviruses in mosquito populations at equine facilities in eastern Austria and evaluate the potential circulation of WNV in these regions. Mosquitoes were collected monthly from July to September 2025 at eight locations using BG–Sentinel-2 traps. The captured insects were identified morphologically, pooled by species and sex, and examined using pan-flavivirus RT-PCR targeting the NS5 gene, followed by nested PCR and sequencing. A total of 94 mosquitoes in 40 pools were analysed. The dominant species was Culex pipiens/torrentium (n=76), followed by Culiseta annulata (n=7), Coquillettidia richiardii (n=3) and less common species. The highest numbers were recorded in August. Seven pools tested positive for flaviviruses (17.5%). Six of these positive pools contained Culiseta annulata, one contained Coquillettidia richiardii. Sequence analysis revealed the presence of insect-specific flaviviruses only, including Culex flavivirus, Flavivirus spp. not further identifiable and Flavivirus AV-2011/Spain. The results indicate the active circulation of insect-specific flaviviruses within mosquito populations in eastern Austria, as well as the first detection of these viruses in Coquillettidia richiardii in the country. The absence of WNV in this study may be associated with the limited sample size and the restricted spatial coverage. This study emphasises the importance of ongoing vector surveillance and provides insights into flavivirus ecology and potential interactions between insect-specific flaviviruses and WNV.