Virulence and transmission vary between Usutu virus lineages in Culex pipiens.
Usutu virus (USUV) is a zoonotic arbovirus infecting mainly wild birds.It is transmitted by ornithophilic mosquitoes, mainly of the genus Culex from birds to birds and to several vertebrate dead-end hosts.Several USUV lineages, differing in their virulence have emerged in the last decades and now co-circulate in Europe, impacting human populations.