HPAI H5N1 Reaches Crozet and Kerguelen Islands
A new study published in Nature Communications reports the first confirmed incursions of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b into the sub-Antarctic Crozet and Kerguelen archipelagos. The virus was detected in October 2024 during mass die-offs of southern elephant seals and seabirds on Possession Island.
Testing confirmed infection in more than 90% of carcasses across multiple species, including elephant seals, king penguins, and skuas. Genome sequencing placed the viruses within clade 2.3.4.4b genotype B3.2, and phylogeographic analyses suggest introductions from South Georgia in the South Atlantic. Evidence of cross-species transmission was observed, and some viral isolates carried the PB2 E627K mutation linked to mammalian adaptation.
While serological tests indicated that a few elephant seal pups developed antibodies, mortality was extremely high. The study warns that the spread of H5N1 to these remote ecosystems poses a serious conservation threat and increases the risk of further dispersal toward Australia and New Zealand.
