Abstract Title
Mass Mortality Caused by Highly Pathogenic Avian Influenza H5N1 in Black-legged Kittiwakes in Norway during Breeding Season 2023
Abstract
The black-legged kittiwake (Rissa tridactyla), an endangered species in Norway, experienced an outbreak of Highly Pathogenic Avian Influenza (HPAI) in July 2023, impacting Ekkerøy, the largest kittiwake breeding colony in mainland Norway. Within a month, 15,235 dead birds were collected, representing 50% of the colony. Sheep in direct contact with infected birds exhibited no clinical signs. We describe the outbreak, characterize the disease in kittiwakes, and assess the zoonotic risk to enhance understanding of HPAI in this species and improve future outbreak responses.
Necropsies were performed on ten kittiwakes shortly after death. Swabs and tissue were collected for virus detection and characterization using rRT-PCR and WGS. Phylogenetic analysis and FluMut screening were performed. Pathological investigations and virus receptor studies included histopathology, immunohistochemistry, RNA Scope and lectin staining. In June 2024, we collected sera from 220 likely exposed sheep and screened for Influenza A virus antibodies.
The outbreak was caused by HPAI virus H5N1 clade 2.3.4.4b genotype EA-2022-BB. Viruses were mainly avian-adapted. The kittiwakes displayed neurological signs and had high viral loads in the brain. Pathological findings showed acute fatal systemic viral infection, affecting primarily brain and pancreas. Influenza A receptors were present in vascular endothelium, including in the brain, and gastrointestinal tract and lung epithelium. No Influenza A antibodies were detected in exposed sheep. Movement restrictions and carcass removal were part of the outbreak response.
We encourage further research on the long-term consequences of the HPAI outbreak in the kittiwake population. The outbreak response should follow a One Health approach.
Necropsies were performed on ten kittiwakes shortly after death. Swabs and tissue were collected for virus detection and characterization using rRT-PCR and WGS. Phylogenetic analysis and FluMut screening were performed. Pathological investigations and virus receptor studies included histopathology, immunohistochemistry, RNA Scope and lectin staining. In June 2024, we collected sera from 220 likely exposed sheep and screened for Influenza A virus antibodies.
The outbreak was caused by HPAI virus H5N1 clade 2.3.4.4b genotype EA-2022-BB. Viruses were mainly avian-adapted. The kittiwakes displayed neurological signs and had high viral loads in the brain. Pathological findings showed acute fatal systemic viral infection, affecting primarily brain and pancreas. Influenza A receptors were present in vascular endothelium, including in the brain, and gastrointestinal tract and lung epithelium. No Influenza A antibodies were detected in exposed sheep. Movement restrictions and carcass removal were part of the outbreak response.
We encourage further research on the long-term consequences of the HPAI outbreak in the kittiwake population. The outbreak response should follow a One Health approach.
Co-Author(s)
Grim Rømo1, Caroline Piercey Åkesson1, Tone Kristin Reiertsen3, Johanna Hol Fosse1, Cathrine Arnason Bøe1, Lars Austbø1, Johan Åkerstedt1, Maryam Saghafian1, Kristin Stangeland Soetaert1, Bjørnar Ytrehus1, Kristin Udjus1, Ida Kristin Myhrvold1, Morten Helberg2, Olav Hungnes4, Britt Gjerset1, Silje Granstad1, Gørill Hogseth5, Siri Løtvedt5, Anne Døsen5, Ragnhild Tønnessen1
1Norwegian Veterinary Institute, Ås, Norway
2Birdlife Norway, Trondheim, Norway
3Norwegian Institute of Nature Research, Tromsø, Norway
4Norwegian Institute of Public Health, Oslo, Norway
5Norwegian Food Safety Authority, Brumunddal, Norway
Abstract Category
Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds