Mutated avian flu infects both birds and mammals, study finds
The virus has killed thousands of mammals in South America.
Genetic adaptions which may be helping the H5N1 strain of highly pathogenic avian influenza (HPAI) to spread among marine mammals do not prevent it from continuing to infect birds, a new study has found.
Researchers from the University of California, USA, and the National Institute of Agricultural Technology in Argentina sequenced the genome of virus samples collected from the Punta Bermeja sea lion rookery in Argentina.
They found that the samples taken from four sea lions, one fur seal, and a tern were almost identical. Nine mutations were present, the same mutations that previous research had found in sea lions and a human in Peru and Chile.
Although the mutations had previously been seen in mammals, the discovery of the same adaptations in the virus sample taken from the tern is the first such finding.
Agustina Rimond, first author of the study, said: “This confirms that while the virus may have adapted to marine mammals, it still has the ability to infect birds. It is a multi-species outbreak.”
The H5N1 variant emerged in 2020 and has since spread around the world, reaching the UK in 2021and South America in 2022. The virus is estimated to have killed at least 600,000 wild birds and 50,000 mammals in South America.
Another recent paper by some of the same researchers showed that the virus killed 70 per cent of elephant seal pups in the Valdes Peninsula and nearby areas during the 2023 breeding season.
Marcela Uhart, who was involved in both studies, said: ““When [the virus] first came to Argentina, we didn’t know if it would affect elephant seals. We never imagined the magnitude of what was to come.”
The new study is set to be published in the journal Emerging Infectious Diseases.
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The BSAVA has opened submissions for the BSAVA Clinical Research Abstracts 2026.
