UK mosquitoes are competent to transmit Usutu virus at native temperatures

Abstract

AbstractUsutu virus (USUV) is an emerging zoonotic virus transmitted primarily byCulexmosquitoes. Since its introduction into Europe from Africa during the late 20thcentury, it has caused mortality within populations of passerine birds and captive owls, and can on occasion lead to disease in humans. USUV was first detected in the UK in 2020 and has become endemic, having been detected in either birds and/or mosquitoes every subsequent year. Importantly, the vector competence of indigenous mosquitoes for the circulating UK (London) USUV strain at representative regional temperatures is still to be elucidated. This study assessed the vector competence of five field-caught mosquito species/biotypes,Culex pipiensbiotypemolestus,Culex pipiensbiotypepipiens,Culex torrentium,Culiseta annulataandAedes detritusfor the London USUV strain, with infection rates (IR) and transmission rates (TR) evaluated between 7 to 28 days post-infection. Infection and transmission were observed in all species/biotypes aside fromAe. detritusandCx. torrentium. ForCx. pipiensbiotypemolestus, transmission potential suggests these populations should be monitored further for their role in transmission to humans. Furthermore, bothCx. pipiensbiotypepipiensandCs. annulatawere shown to be competent vectors at 19°C indicating the potential for geographical spread of the virus to other UK regions.