Massive outbreak of Influenza A H5N1 in elephant seals at Península Valdés, Argentina: increased evidence for mammal-to-mammal transmission - bioRxiv

[Mary Wilson]

Posted June 01, 2024.​​

doi: https://doi.org/10.1101/2024.05.31.596774​

Marcela Uhart, Ralph E. T. Vanstreels, Martha I. Nelson, Valeria Olivera, Julieta Campagna, Victoria Zavattieri, Philippe Lemey, Claudio Campagna, Valeria Falabella, Agustina Rimondi​

ABSTRACT

H5N1 high pathogenicity avian influenza (HPAI) viruses of the clade 2.3.4.4b have killed thousands of marine mammals in South America since 2022. In October 2023, following outbreaks in sea lions in Argentina, we recorded unprecedented mass mortality (∼17,000 individuals) in southern elephant seals (Mirounga leonina) at Península Valdés. Seal pups were disproportionately affected. Adult seals departed early, disrupting social and breeding structure. Frequent interactions with sea lions and scavenging by seagulls were observed. Deaths of terns concurred with seals but peaked weeks later. HPAI H5N1 was confirmed in seals and terns. Moreover, genomic characterization showed viruses from pinnipeds and terns in Argentina form a distinct clade with marine mammal viruses from Peru, Chile and Brazil. These mammal-clade viruses share an identical set of mammalian adaptation mutations which are notably also found in the terns. Our combined ecological and phylogenetic data support mammal-to-mammal transmission and occasional mammal-to-bird spillover. To our knowledge, this is the first multinational transmission of H5N1 viruses in mammals ever observed globally. The implication that H5N1 viruses are becoming more evolutionary flexible and adapting to mammals in new ways could have global consequences for wildlife, humans, and/or livestock.

https://www.biorxiv.org/content/10.1101/2024.05.31.596774v1.full
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[JJackson]

I see no mention of penguins but I once sailed to the peninsula and it was difficult to walk as every little bush had a penguin on its nest under it. A "Magellanic penguin and H5N1" search gave an NIH paper that seemed to hint they may have some resistances, but as it over a year old and with data from the South Shetlands there is likely to have been some shifts in the strain.