Aedes albopictus
USUV's host range includes primarily "Culex" mosquitoes and birds. The main bird hosts are blackbirds ("Turdus merula"), magpies ("Pica pica") and owls, including the great grey owl ("Strix nebulosa"). In addition to humans, the virus has been isolated from "Pipistrellus" bats, and anti-USUV antibodies have been found in horses, dogs, deer, wild boar, rodents and shrews. Humans and horses are dead-end hosts. The vector is one of several mosquitoes that bite birds, in Europe particularly "Culex pipiens". For example, a 2008–2009 survey of mosquitoes and birds in the Emilia-Romagna region of Italy detected USUV in 89 "C. pipiens" pools and in 2 "Aedes albopictus" pools, suggesting the possible involvement of "A. albopictus" in the virus cycle. The virus was also found in twelve wild birds, primarily Eurasian magpies ("P. pica"), hooded crows ("Corvus cornix"), and Eurasian jays ("Garrulus glandarius"). In Africa multiple "Culex" species are involved, as well as several species of "Aedes" and other mosquitoes.