Abstract

An extensive survey for the detection of Highly Pathogenic Avian Influenza virus (HPAIV) H5 in seabird species is reported here. It was conducted between December 2023 and January 2024, in thirteen breeding sites spanning from the northeastern sector of the Antarctic Peninsula to the Ross Sea, including the coasts of the Bellingshausen Sea and the Amundsen Sea. Nine individuals from Pygoscelis adeliae and Leucocarbo bransfieldensis tested positive for RT-PCR amplification of a H5 segment of HPAIV in two different locations on the Antarctic Peninsula. This study suggests the possibility of the first cases of HPAIV H5 in the Antarctic continent, potentially adding two new species to the list of infected species. It also highlights the southernmost suspected cases identified to date of surveillance, and notably, no cases were detected between the Antarctic Peninsula and the Ross Sea. © The Author(s) 2025.