Avian Flu’s Spread To Remote Antarctic Islands – Expert Reaction

Sunday, 15 September 2024, 11:07 pm
Press Release: Science Media Centre

New research has detailed the extent of how the highly pathogenic avian flu virus H5N1 rapidly spread into wildlife on an island off the coast of mainland Antarctica, as well as the Falkland Islands.

The fragile ecosystem of the Antarctic island of South Georgia had been free of the virus until it was first detected during the 2022-23 summer season. Genetic assessment found the virus spread from South America, likely through migratory birds, and infected a range of birds such as black-browed albatross, skuas, kelp gulls, and even two seal species.

Aotearoa New Zealand is one of the last places on Earth that has never had a case of the virus, which is decimating wild birds and causing havoc for chicken farmers around the world.

The Science Media Centre asked NZ experts to comment on the research.

Professor Brett Gartrell, Group Leader, Wildbase, School of Veterinary Science, Massey University, comments:

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“This is an important paper documenting that highly pathogenic avian influenza (HPAI) has spread into Antarctica and the subantarctic Islands for the first time. It is of great interest and concern to us as it provides us with some information on how the virus is behaving in previously unexposed seabirds and mammals, which allows us a better risk assessment of the virus making its way into Oceania, the last continental area of the world unaffected by this clade of the virus. There is cause for some hope in that penguin species haven’t been severely affected to date, and that while marine mammals in the subantarctic have been severely affected there is no evidence yet of transmission between mammals.

“However, the species of seabirds now known to be affected is of concern for us in New Zealand, as many of these species — such as skua, giant petrels, kelp gulls and albatross species — have circumpolar ranges which include the subantarctic island in New Zealand territory and the mainland of New Zealand. With the movement of HPAI into Antarctica, the risk of the virus making its way to New Zealand is increasing.

“New Zealand is home to incredible seabird diversity with 96 breeding seabird taxa and the highest global diversity of albatross, petrels, penguins and shags. Many of these species are critically endangered, with several in significant decline. The impact of HPAI on these populations could be severe, and could spill over into the island retreats we use for the conservation management of many other endangered species of birds, such as kākāpō, and rowi. If HPAI makes it to mainland New Zealand, then it could become a threatening process for our most critically endangered species like southern dotterels, shore plovers and fairy prions.

“The Ministry of Primary Industries and the Department of Conservation have been working to prepare for any incursion of HPAI into New Zealand, but this paper demonstrates that it's difficult to predict which species of birds and mammals may be affected and how badly their populations will be affected.”

No conflicts of interest.

Professor Jemma Geoghegan, Virologist, University of Otago, comments:

“This study details the detection of clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (bird flu) in the Antarctic and sub-Antarctic regions off the coast of South America.

“The authors confirmed H5N1 in many species, including both the southern fulmar and black-browed albatross. These species, along with many others, migrate northward from Antarctica to New Zealand, South America and Australia, highlighting the very real threat that this virus could be introduced to New Zealand via such migratory birds.

“By generating virus genomes, this study showed that the sequences from South Georgia and the Falkland Islands clustered with H5N1 viral sequences obtained from South America between October 2022 and October 2023.

“While, for now at least, HPAI seems to have had relatively low impact to Antarctica, it is vital to continue to understand the frequency of viral introductions and spread into this region by generating and sharing virus genomes. Nevertheless, there are a limited number of sequences deposited in public databases from H5N1 detections in South America, which hugely limits interpretation. This study illustrates the usefulness of virus genomes and highlights the need for rapidly generating and openly sharing them.”

No conflicts of interest.

Distinguished Professor Nigel French, Massey University, comments:

“The globally devastating strain of highly pathogenic bird flu moved through South America to the sub-Antarctic region in 2023, and onto the Antarctic mainland earlier this year. This was an important development that raised the risk of a southern incursion into Oceania – the last continent remaining free of this strain of bird flu. Careful monitoring of the situation on the Antarctic mainland and particularly the Ross Sea region is important to enable Aotearoa to assess the dynamic threat to our wild bird and mammal populations, as well as the risk to farmed livestock and people.

“This study reports the findings from wild bird and mammal samples collected from the sub-Antarctic islands of South Georgia and the Falklands between October and December 2023. These are important areas for biodiversity and conservation with many species considered vulnerable to infectious diseases. Through genetic analysis and careful reconstruction of the ancestral history of the viruses they show the likely times and South American origin of incursions into the region. This is crucial to assess the likely risks of re-incursions into the Antarctic Region and the onward risk to the equally fragile ecosystem of the Antarctic mainland.

“The ability to reconstruct historical events, and anticipate future spread, depends on having publicly available virus sequences deposited in international databases. The authors conclude that their interpretation was limited by the availability of genome sequences, and that this needs to be improved if we are to gather crucial information on how these viruses are being spread and put measures in place to protect these ecosystems.”

No conflicts of interest.

Dean Anderson, Ecological Modeller, Manaaki Whenua – Landcare Research, comments:

“This study provides evidence on the viral transmission pathway via migratory birds, which is both interesting and important. However, since some wild animal populations in the Antarctic region are indeed at risk of HPAI, the conclusions of low impact to penguin species seems under-supported, particularly since it is not accompanied by the explicit caveat that this comes from a very limited sample. More evidence is likely needed for such conclusions, such as from investigations incorporating robust sampling efforts and targeted carcass searches.”

No conflicts declared.

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