Serological surveillance to track impact of a highly pathogenic H5N1 outbreak on seabird populations in Atlantic Canada compared to historical infection patterns

Recent outbreaks of highly pathogenic avian influenza clade 2.3.4.4b H5Nx viruses (HPAIVs) have caused significant mortality in wild birds, particularly seabirds. We investigated active influenza A virus (IAV) infections and the seroprevalence of anti-IAV antibodies, including H5-specific antibodies, in seabirds in Atlantic Canada during 2022-2023. These results were compared to data from 2011-2016 to evaluate changes in infection rates following the incursion of HPAIV into the region in 2021. We sampled 1073 seabirds belonging to multiple species. Active HPAIV infections were detected only in 2022, with Common Murres showing the highest prevalence at 64% (n=42) followed by Black-legged Kittiwakes at 13% (n=39). Seroprevalence of general anti-IAV antibodies varied between years for most species, with Common Murres and Atlantic Puffins having higher seroprevalence rates post HPAIV arrival. For Common Murres, H5-specific antibodies were only detected post HPAIV arrival (21% (n=28) in 2022 and 76% (n=17) in 2023). We also analyzed capture-recapture data for Atlantic Puffins and found consistent survival rates from 2021-2023, indicating low mortality. Higher seroprevalence was observed for adult gulls in comparison to sub-adult gulls across all years, with sub-adult gulls having 0% seroprevalence for most years, highlighting age-related differences in exposure. Despite no active infections detected in 2023, high seroprevalence across species suggests persisting immunity or recent virus circulation. These findings underscore the importance of serological monitoring in tracking IAV dynamics, as antibody detection provides critical insights into past HPAIV exposure, even with low active infection rates, with implications for avian population health monitoring.

Ishraq Rahman1, Jordan Wight1,2 Joshua T. Cunningham3, Hannah L. Wallace4,5, Paloma S. Ochoa1, Christopher R.E. Ward6, Gregory J. Robertson3, Sabina I. Wilhelm6, Tamiru Alkie7, Wanghong Xu7, Dmytro Zhmendak7, Yohannes Berhane7, Sydney M. Collins8, William A. Montevecchi9, Antoine Morel9, Pierre-Paul Bitton9, Michelle K. Saunders10, Jason Dicker10, Stephanie Avery-Gomm3, Robert A. Ronconi11, Kathryn E. Hargan1 and Andrew S. Lang1 1Department of Biology, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada 2National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada 3Wildlife Research Division, Environment and Climate Change Canada, Mount Pearl, Newfoundland and Labrador, Canada 4Division of Biomedical Sciences, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada 5Medical Microbiology and Infectious Disease, University of Manitoba, Winnipeg, Manitoba, Canada 6Canadian Wildlife Service, Environment and Climate Change Canada, Mount Pearl, NL, Canada 7National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Manitoba, Canada 8Cognitive and Behavioural Ecology Program, Departments of Psychology and Biology, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada 9Department of Psychology, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada 10Department of Lands and Natural Resources, Nunatsiavut Government, Nain, Newfoundland and Labrador, Canada 11Canadian Wildlife Service, Environment and Climate Change Canada, Dartmouth, NS, Canada

Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds