First Detection of Usutu Virus (USUV) in Scotland

¨   Usutu virus (USUV), a mosquito-borne flavivirus, was detected in blackbirds in Scotland for the first time during summer 2025.

¨ The detection was publicly announced on 1 April 2026 after the virus was confirmed on the Isle of Arran.

¨ Usutu virus belongs to the genus Flavivirus and is transmitted mainly by mosquitoes.

¨     The virus was first identified in Africa and has since spread to several European countries.

¨     It primarily infects wild birds, especially blackbirds.

¨     In rare cases, the virus can also infect humans.

¨     Residents on the Isle of Arran reported dead blackbirds and birds showing neurological symptoms.

¨     The Animal and Plant Health Agency (APHA) confirmed USUV RNA in two blackbirds using Reverse Transcription–PCR (RT-PCR) under its National Passive Wild Avian Surveillance Programme.

¨     The investigation involved collaboration between APHA’s Vector-Borne Disease Group, SRUC Veterinary Services, and the Mosquito Scotland Research Programme at the University of Glasgow.

¨     Phylogenetic analysis classified the Scottish samples under the Usutu virus Africa 3.2 lineage.

¨     The findings suggest that the virus spread from existing UK infections rather than through a new introduction.

¨     Usutu virus has caused declines in blackbird populations in several parts of Europe.

¨  The virus has been circulating in south-east England for the past six years, where mosquito-borne transmission in wild birds has been confirmed.

¨     Passive surveillance of dead or sick birds is a standard method used in the United Kingdom to monitor avian diseases.