Abstract
Highly pathogenic avian influenza viruses (HPAIVs) from the Goose/Guangdong lineage H5 clade 2.3.4.4b have spread globally leading to a rise of infections in mammals.
Between June 2022 and February 2024, six wild red foxes (Vulpes vulpes) were diagnosed with HPAIV infection in Norway: three foxes in 2022 (H5N1), one in 2023 (H5N1) and two foxes in 2024 (H5N5).
Our aim was to enhance understanding of HPAI in red foxes, focusing on the identified viruses and their zoonotic potential. We investigated the pathological effects of HPAIV infection, compared the genetic makeup of viruses in foxes to those in wild birds, and looked for markers of adaptation to mammals.
Whole genome sequencing and phylogenetic analysis revealed that fox detections in 2022 coincided with an outbreak of H5N1 genotype C in northern gannets (Morus bassanus) in the North Sea. The virus from the fox in 2023 was highly similar to H5N1 genotype BB circulating in gulls in Northern Europe the same year. The two viruses from the foxes in 2024 were most similar to H5N5 genotype I viruses that appear to have persisted in Norway since 2022. Mutation analyses identified the PB2-E627K mutation in viruses from two foxes in 2022.
Pathological examination revealed changes consistent with a systemic infection, and was limited to the lungs and brain. PCR analysis confirmed high viral loads in these tissues.
To conclude, our investigations show that HPAI infections in red foxes were spillover events with avian-adapted viruses. More information about the epidemiology of HPAI H5N5 is warranted.
Between June 2022 and February 2024, six wild red foxes (Vulpes vulpes) were diagnosed with HPAIV infection in Norway: three foxes in 2022 (H5N1), one in 2023 (H5N1) and two foxes in 2024 (H5N5).
Our aim was to enhance understanding of HPAI in red foxes, focusing on the identified viruses and their zoonotic potential. We investigated the pathological effects of HPAIV infection, compared the genetic makeup of viruses in foxes to those in wild birds, and looked for markers of adaptation to mammals.
Whole genome sequencing and phylogenetic analysis revealed that fox detections in 2022 coincided with an outbreak of H5N1 genotype C in northern gannets (Morus bassanus) in the North Sea. The virus from the fox in 2023 was highly similar to H5N1 genotype BB circulating in gulls in Northern Europe the same year. The two viruses from the foxes in 2024 were most similar to H5N5 genotype I viruses that appear to have persisted in Norway since 2022. Mutation analyses identified the PB2-E627K mutation in viruses from two foxes in 2022.
Pathological examination revealed changes consistent with a systemic infection, and was limited to the lungs and brain. PCR analysis confirmed high viral loads in these tissues.
To conclude, our investigations show that HPAI infections in red foxes were spillover events with avian-adapted viruses. More information about the epidemiology of HPAI H5N5 is warranted.
Co-Author(s)
Cathrine A. Bøe, Norwegian Veterinary Institute
Line Olsen, Norwegian Veterinary Institute
Silje Granstad, Norwegian Veterinary Institute
Britt Gjerset, Norwegian Veterinary Institute
Maryam Saghafian, Norwegian Veterinary Institute
Olav Hungnes, Norwegian Institute of Public Health
Andreas Rohringer, Norwegian Institute of Public Health
Bjørnar Ytrehus, Norwegian Veterinary Institute
Ragnhild Tønnessen, Norwegian Veterinary Institute
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health