Austral Ecology: Impacts of a Potential HPAI H5N1 Incursion on Australian Wildlife

 
Credit FAO

#18,456

Although Australia and New Zealand have both experienced outbreaks of homegrown HPAI viruses (see here and here), the HPAI H5Nx virus currently on its world tour has yet to reach Oceania.  

A year ago, however, Australia did see its first imported human case (see EID Journal: Influenza A(H5N1) Virus Clade 2.3.2.1a in Traveler Returning to Australia from India, 2024).

Remarkably, even though H5N1 emerged in Southeast Asia more than 25 years ago, and has been widely reported across much of the Indonesian archipelago for decades, the virus has never managed to get a foothold in Oceania.

It has long been believed that that this good fortune is due in part to the Wallace and Weber lines - imaginary dividing lines used to mark the difference between animal species found in Australia and Papua New Guinea and the rest of Southeast Asia. 

While separated by a relatively narrow strait, on the western side you'll find Elephants, monkeys, leopards, tigers, and water buffalo while on the eastern side, you'll mostly find marsupials (kangaroos, Koalas, wombats, etc.).

These stark faunal differences also extend to birds, reptiles, and even insects.

Previous studies have suggested very few migratory birds appear to cross the Wallace line (see The Australo-Papuan bird migration system: another consequence of Wallace's Line).  

Last fall, however, in Virus Evol. : Contrasting Dynamics of Two Incursions of Low Pathogenicity Avian Influenza Virus into Australia, we saw evidence of recent incursions of both Eurasian and North American LPAI viruses into Australian birds.

Add in the fact that HPAI H5 has now been reported in the Antarctic region, there are growing concerns that Oceania's luck with H5 may be on borrowed time (see Australia : Biodiversity Council Webinar on HPAI H5 Avian Flu Threat).

All of which brings us to a brief open access report - published late last week in Austral Ecology - which warns that `Avian influenza HPAI H5N1 is catastrophic and will likely have negative consequences for Australian wildlife.'

I've reproduced the link, and a brief excerpt below. Follow the link to read it in its entirety.

Impacts of a Potential HPAI H5N1 Incursion on Australian Wildlife

Sara Ryding, Tobias A. Ross, Marcel Klaassen, Michelle Wille
First published: 25 April 2025
https://doi.org/10.1111/aec.70048

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ABSTRACT

Avian influenza HPAI H5N1 is catastrophic and will likely have negative consequences for Australian wildlife.

Summary

• HPAI H5N1 has thus far affected more than 400 wild bird species and 40 mammal species globally since 2021, marking it an animal disease of unprecedented magnitude.

• The virus has not yet arrived in Oceania, but there is a substantial risk it will do so via migratory sea- and/or shorebirds.

• In addition to wild birds, sustained transmission means HPAI H5N1 has also severely impacted marine mammals, suggesting a risk of wide harm to Australia's fauna.

• Efforts to mitigate impacts on Australia's fauna include enhanced surveillance of wild populations, protecting habitat to increase species' resilience and the establishment of rapid response plans to manage outbreaks. 

         (Continue . . . )

Aside from the obvious damage that HPAI H5 could do to the fauna of Oceania, the H5 virus would also be introduced to an array of LPAI viruses - and a number of animal hosts - it had never encountered before.  

While there is no way of knowing what might come from that, the last thing we need is for this highly mutable virus to have more evolutionary options going forward. 

Stay tuned.