Researchers from a major U.S. university have confirmed that the highly pathogenic H5N1 bird flu virus has evolved to spread among marine mammals and seabirds, creating an immediate concern for wildlife health and ecosystem balance. The findings appear in a peer‑reviewed scientific venue, underscoring the urgency of monitoring H5N1’s reach beyond birds and typical avian hosts. The discovery adds to a growing body of evidence that flu viruses can adapt to new species and environments, which could influence how wildlife surveillance and preventive measures are planned in North America and beyond.
Samples were collected from four sea lions, a fur seal, and a tern found deceased at a sea lion facility along the coastal fringe of Argentina. Across all specimens, tests detected H5N1, signaling a multi‑species exposure storyline rather than a single isolated incident. This pattern raises important questions about how the virus moves through marine ecosystems and whether coastal food webs might facilitate its persistence or spread among different hosts in the ocean environment.
Genome sequencing demonstrated a striking similarity of the viral genomes among the different animals tested, suggesting a clonal expansion or rapid transmission event within this maritime setting. The nearly identical sequences indicate that the same viral lineage circulated across several species, reinforcing concerns about the potential for cross‑species jump and the stability of this strain once it enters marine mammal populations.
Experts note that while the immediate risk to humans remains low at this stage, the possibility of mutations as the virus circulates in mammals could alter the threat level. The current evidence points to a virus well adapted to marine mammals, yet still capable of infecting birds, which means broader surveillance is warranted across both avian and mammal communities to detect any shifts in transmission dynamics early.
Earlier warnings have highlighted the dangers of bird flu spreading to remote regions such as Antarctica, where unique wildlife communities could be affected. The new observations from South American coastal ecosystems emphasize the need for comprehensive monitoring programs that track viral evolution, host range, and environmental factors that could influence the trajectory of H5N1 in marine habitats. By maintaining vigilance and collaborating across research networks, scientists aim to map risk areas, anticipate outbreaks, and support wildlife health strategies that protect vulnerable species across oceans.