Transmission Routes of Oropouche Virus: Potential Role of European Biting Midges and First Oral Infection Attempt in Wild-Caught Culicoides (Subgenus Avaritia).

Oropouche virus (OROV) is an emerging arbovirus primarily endemic to South America, capable of infecting humans, diverse animals, and multiple vector species. Although its ecology remains poorly understood, increased globalisation and human mobility raise concerns regarding potential introduction into Europe. To evaluate European risk, vector competence trials were conducted using Italian Culicoides obsoletus/scoticus and C. imicola, major vectors of livestock orbiviruses, orally exposed to a 2024 Cuban reassortant OROV strain. Of 260 surviving C. obsoletus/scoticus and 65 C. imicola midges, all samples tested negative for OROV RNA, suggesting limited vector competence. These findings indicate that tested European Culicoides populations are unlikely to support OROV transmission. Nevertheless, the virus's broad host and vector range, reassortment potential, and presence of anthropophilic midges in Europe warrant continued surveillance and vector competence studies. Improved understanding of transmission dynamics, reservoir hosts, and potential vectors is critical for preparedness against Oropouche virus introduction and spread in non-endemic regions.