H5N5 virus transmission is driven by repeated cross-Atlantic introductions and transmission among high latitude seabirds

H5N5 viruses have been transported by high latitude seabirds and shorebirds across the Atlantic at least 9 times, with cross-continental movement linked to Arctic or sub-Arctic pathways.

• Why it matters: The first human H5N5 case in Washington State raised concern that this virus’s ecology differs from dominant H5N1, but its movement and circulation patterns were unclear.
• What they did: Using 354 global H5N5 genomes, the study inferred repeated Atlantic introductions, seasonal timing (fall and spring), and a plausible Arctic/sub-Arctic route with about a year of cryptic circulation before human spillover.
• The result: The findings indicate far more intercontinental movement than previously recognized and distinct host and geographic patterns, supporting enhanced surveillance given the virus’s capacity to infect a person.

AI summary of the abstract · may contain errors · not medical advice · read the paper.