USUV has been found across Europe.. Wild birds are the main carrier of the virus, and the blackbird is one of the most common UK birds, external.
Andra-Maria Ionescu, of APHA, said: “The detection of Usutu virus in blackbirds in Scotland shows that countries further north are now facing an increased risk of mosquito-borne viruses.
“These findings highlight importance and need for improved, nationwide wild bird and mosquito surveillance to better assess the risks posed to animal and human health.”
Islanders on Arran spotted a cluster of blackbirds displaying unusual neurological behaviour, and found dead birds, during the summer last year.
Prof Heather Ferguson, Mosquito Scotland project lead at the University of Glasgow, said: “Mosquito-borne diseases are increasingly likely to get a foothold in the UK, including in Scotland, as our environment continues to change.”
She added: “When news of suspicious blackbird deaths consistent with Usutu came through, we were able to almost immediately deploy a team of experts to Arran for rapid follow up and investigation.
“This allowed us to confirm the presence of several different mosquito species near the locations where infected birds were found, including several known to be capable of spreading Usutu.”