Searching for high pathogenicity avian influenza virus in Antarctica

Abstract

The current panzootic spread of high pathogenicity avian influenza virus (HPAIV) subtype H5N1 clade 2.3.4.4b has caused unprecedented mortality in wild animals worldwide¹. In 2022, the virus caused mass mortality of seabirds and marine mammals in South America, which raised concerns about HPAIV spreading to Antarctica. The wildlife in Antarctica is seasonally dense due to high populations found in breading colonies of birds and mammals, and many Antarctic sites are remote and difficult to access, meaning that HPAIV could have dramatic effects on its fauna without immediately being noticed. As a result, surveillance efforts in this area are crucial.

The detection of HPAIV in the sub-Antarctic islands of South Georgia was first reported in October 2023. It caused considerable mortalities of seabirds (for example, skuas, gulls and albatrosses) and marine mammals (for example, elephant seals and sea lions) during the subsequent months². Recent phylogenetic analyses of the viral sequences from South Georgia demonstrated a single introduction from South America². Wildlife mortality suspected to be related to HPAIV was reported in Antarctica as early as November 2023 (ref. ³). The first case of HPAIV in Antarctica was confirmed in skuas (Stercorarius sp.) found dead in January 2024 near the Argentinian Primavera Base (Danco Coast, Antarctic Peninsula) and tested in February 2024 in a molecular diagnostic laboratory set up at the Spanish Gabriel de Castilla Station (Deception Island, South Shetland Islands)⁴. Having this on-site laboratory showed it was possible to perform the diagnoses in Antarctica itself, which gives results much faster and avoids the risk of losing sample quality during transport to laboratories outside Antarctica. HPAIV was later reported in dead skuas near the Czech Johann Gregor Mendel base⁵. The finding of sporadic or potential cases of HPAIV-infected skuas indicated that the virus had reached Antarctica. In response, we launched the Australis expedition to investigate the spread and impact of HPAIV at several remote sites, following a direct field diagnostic approach with a mobile laboratory on board.