Infectious Disease · Public Health · 2 h ago
H5 Influenza Antibodies Detected in East Greenland Polar Bears
An observational serologic study screened 109 plasma samples from East Greenland polar bears collected during 2016–2025. Four bears sampled in 2025 had antibodies consistent with exposure to highly pathogenic H5 clade 2.3.4.4b viruses, supporting wildlife surveillance in Arctic ecosystems.
- Researchers screened 109 polar bear plasma samples collected during 2016–2025.
- Influenza A antibodies were first detected in 2024.
- Four bears had antibodies consistent with H5 clade 2.3.4.4b exposure.
- Serology does not establish active infection or human transmission risk.
Researchers examined influenza A exposure in East Greenland polar bears using 109 plasma samples collected during legal subsistence hunts near Scoresby Sound during 2016–2025. Bears appeared healthy according to hunters. The observational study screened samples for influenza A nucleoprotein antibodies, followed by hemagglutination inhibition testing of nine positive and three negative samples against representative H5 and H7 viruses.
No influenza A antibodies were detected in samples collected before 2024. Antibodies were detected in 3 of 14 bears in 2024 (21%; 95% CI 8%–48%) and 6 of 14 in 2025 (43%; 95% CI 21%–67%). Four bears sampled in 2025 had antibodies reactive to H5N1 viruses within clade 2.3.4.4b, consistent with exposure to this highly pathogenic lineage. Their apparently healthy condition at harvest suggests survival after exposure, rather than uniformly fatal infection.
The findings support considering polar bears as sentinels for avian influenza circulation in Arctic ecosystems, with potential relevance to zoonotic surveillance. However, annual sample sizes were small, and serology does not establish active infection, transmission routes, or human risk. Cross-reactivity with low-pathogenicity H5 viruses remains possible, although the observed antibody pattern supported clade 2.3.4.4b exposure. The report is an early-release article in Emerging Infectious Diseases and may undergo changes before final publication.
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Emerging Infectious Diseases: Evidence of Exposure to Highly Pathogenic Avian Influenza H5 Viruses in East Greenland Polar Bears ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.