Considerable mortality of blackbirds due to usutu is reoccurring

From July to September 2024 increased disease occurrence and correlating mortality were noticed, especially in blackbirds. Reports to the DWHC and Sovon increased steeply (see also https://dwhc.nl/2024/09/opnieuw-verhoogde-sterfte-onder-merels/).

In this period birds, including blackbirds, were collected to establish cause of death and investigate the presence of usutu virus. The investigation regarding the cause of death of these birds is still ongoing, however, in multiple of these birds usutu virus could be detected via PCR.

In total 99 birds were tested with PCR for usutu virus. Of these 99 birds, 25 were positive for usutu with the majority of these positive cases being blackbirds. Out of the 21 blackbirds tested, 18 were positive for usutu virus.

We are kindly asking you to report any dead songbirds you may find to us.