Abstract
Highly pathogenic avian influenza (HPAI) in wild birds is a major emerging disease, and a cause of increased mortality during outbreaks. The Common buzzard (Buteo buteo) has a considerable chance of acquiring the infection and therefore may function as bio-sentinel for the presence of virus in wildlife. This study aimed to determine the virus distribution and associated pathological changes in the tissues of Common buzzards that died with HPAI H5 virus infection during the 2020–2021 epizootic. Eleven freshly dead, HPAI H5 virus-positive Common buzzards were necropsied. Based on RT-PCR, all birds were systemically infected with HPAI H5N8 virus, as viral RNA was detected in cloacal and pharyngeal swabs and in all 10 selected tissues of the birds, with mean Ct values per tissue ranging from 22 for heart to 32 for jejunum. Based on histology and immunohistochemistry, the most common virus-associated pathological changes were necrotizing encephalitis (9/11 birds) and necrotizing myocarditis (7/11 birds). The proventriculus of two birds showed virus-associated necrosis, indicating tropism of this virus for the digestive tract. Our advice is to collect at least a miniset of samples including brain, heart, liver, and spleen, as these tissues were positive both by RT-PCR and for virus-antigen-associated lesions.
Highlights
Pathogenic avian influenza (HPAI) in wild birds is a major emerging disease, and a cause of increased mortality during outbreaks
Surveillance showed that the first incursions in Europe of the Highly pathogenic avian influenza (HPAI) H5N8 virus occurred in the fall of 2020; the epizootic season extended into winter–spring–summer of 2021, with the outbreaks mainly clustered in two peaks: in November 2020 and March 20214
These analyses showed that the main lesions were HPAI virus-associated inflammation and necrosis in multiple tissues including brain and heart, confirming HPAI as cause of death or severe disease
Summary
Pathogenic avian influenza (HPAI) in wild birds is a major emerging disease, and a cause of increased mortality during outbreaks. The second highest number of detections occurred in raptors (orders Accipitriformes, Strigiformes, and Falconiformes); nine different raptor species were found positive, and Common buzzard (Buteo buteo, order Accipitriformes) accounted for the highest number of detections in r aptors[4]. These birds are infected predominantly by ingesting infected prey. isease[10,11] In this context, the investigation of Common buzzard mortality for HPAI virus could be used in addition to waterfowl mortality as a passive-surveillance system for early warning and duration of the presence of the virus in wild bird populations
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