Detection and spread of high pathogenicity avian influenza virus H5N1 in the Antarctic Region

Abstract

AbstractThe Antarctic is the only major geographical region in which high pathogenicity avian influenza virus (HPAIV) has never previously been detected. The current panzootic of H5N1 HPAIV has decimated wild bird populations across Europe, North America and South America. Here we report on the emergence of clade 2.3.4.4b H5N1 HPAIV in the Antarctic and sub-Antarctic regions of South Georgia and the Falkland Islands respectively. We initially detected H5N1 HPAIV in samples collected from brown skuas at Bird Island, South Georgia on 8thOctober 2023. Since this detection, increased mortalities were observed in brown skuas, kelp gulls, elephant seals and fur seal at multiple sites across South Georgia. We confirmed H5N1 HPAIV in multiple brown skuas and kelp gulls across four different sampling locations in South Georgia. Simultaneously, we also confirmed H5N1 HPAIV in a southern fulmar in the Falkland Islands. Genetic assessment of the virus indicates spread from South America, likely through movement of migratory birds. Here we describe the emergence, species impact and genetic composition of the virus and propose both introductory routes and potential long-term impact on avian and mammalian species across the Antarctic region.