Massive die-off of elephant seals in Argentina due to avian influenza is latest indication that this dangerous virus poses an existential threat to global wildlife
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Whilst humans were busy with the Covid-19 pandemic, the world’s birds and wildlife were hit hard by a pandemic of H5N1 avian influenza.
“H5N1 now presents an existential threat to the world’s biodiversity,” warned Chris Walzer, the Wildlife Conservation Society’s Executive Director of Health, in a statement. “It has infected over 150 wild and domestic avian species around the globe as well as dozens of mammalian species. The bird flu outbreak is the worst globally and also in U.S. history, with hundreds-of-millions of birds dead since it first turned up in domestic waterfowl in China in 1996.”
The so-called “bird flu” is highly transmissible both through airborne droplets and feces-borne infections. The worsening climate crisis is exacerbating it because wild birds are altering their schedules to coincide with optimal migration weather. Thus, the flu virus’s circulation continues and grows, thanks to intensive egg and poultry farming and its characteristically filthy and overcrowded cages crammed with sick and dead birds. This horrific environment is superb for encouraging influenza to mutate into ever-more contagious and deadly forms, through a process known as genetic ‘reassortment’. These increasingly virulent flu viruses then spill over into wild birds that quickly carry it far and wide whilst they migrate, often with devastating consequences.
“First, Great Skuas began dying across islands in Scotland in summer 2021,” reported the Royal Society for the Protection of Birds (RSPB). “Then in winter 2021/22 on the Solway Firth, bird flu killed a third of the Svalbard breeding population of Barnacle Geese – at least 13,200 birds. In winter 2022/23, up to 5,000 Greenland Barnacle Geese died on Islay, as well as hundreds of ducks, swans, gulls and other geese species. Birds of prey such as Peregrine Falcon, Hen Harrier, Buzzard, White-tailed Eagle and Golden Eagle have also been testing positive.”
In fact, almost all of the 77 species of seabirds that breed in the UK have tested positive for H5N1. Unfortunately, documenting this virus in wild birds underestimates the total species diversity as well as the true number of wild birds killed by bird flu. This is because the surveillance scheme only tests dead birds, and not all dead wild birds are reported or collected.
Further, a large diversity of mammals are now dying from HPAI, too.
“Globally, HPAI H5N1 has now infected many mammals — including foxes, pumas, skunks, and both black and brown bears in North America,” Dr Walzer noted. Additionally, it was just reported that a wild polar bear tested positive for H5N1 in Alaska — the first influenza death ever documented in this species (more here).
“Some 700 endangered Caspian seals died from HPAI near Dagestan in 2023,” Dr Walzer continued.
Troublingly, influenza outbreaks in Spain and Finland have also been documented in farmed mink. This is especially dangerous because these small mammals — which, like poultry, are kept in filthy, overcrowded and unhealthy conditions — provide ample opportunities for viral reassortment so it can easily begin to infect other mammals (don’t forget that humans are mammals too) whilst simultaneously increasing its virulence.
This increasingly dangerous HPAI influenza is now found in the Global South, especially along its coasts, because it was carried there by infected migrating seabirds. Hunting or opportunistically scavenging mammals that eat these dead or dying birds can thus be exposed to very large quantities of the virus. This provides H5N1 with a convenient pathway to sneak in and adapt to a new host population that it does not normally infect.
The effects of HPAI influenza can be devastating.
“Sampling efforts suggest that more than 95 percent of the Southern elephant seal (Mirounga leonina) pups born along 300 km of the Patagonia coastline died at the end of 2023,” Dr Walzer pointed out. “It’s the first report of massive elephant seal mortality in the area from any cause in the last half century. The sight of elephant seals found dead or dying along the breeding beaches can only be described as apocalyptic. This 2023 die-off contrasts starkly with the 18,000 pups born and successfully weaned in 2022.”
Could HPAI influenza infect and kill humans, too? Possibly. This concern is especially relevant considering that our health and the health of both wild and domestic animals are inextricably linked. As the global population grows, humans are increasingly moving into previously uninhabited areas, so more humans come into contact with wildlife and their diseases, which increases our pandemic risk. (COVID-19 is but one such example.) Whether it’s H5N1 or a different virus, it’s inevitable that new viruses will continue to emerge and threaten to trigger another human or wildlife pandemic.
“As the virus continues to spread through mammal populations, the World Health Organization (WHO) has called on public health officials to prepare for a potential spillover of H5N1 to people. The ‘R naught’ value — the number of people infected by a single infected person — for COVID initially ranged from 1.5 to 7. For H5N1 among birds, it is around 100,” Dr Walzer reported.
A highly contagious novel pathogen like HPAI influenza that can potentially wipe out entire species can likewise threaten the stability of human populations and societies. For this reason, there is urgent need to safeguard the health of people, their pets and livestock, of wildlife, as well as conserve global biodiversity and protect the natural environment to reduce the threat of emerging diseases.
“It is imperative that we take a collaborative One Health approach to identifying emerging strains of bird flu across the globe to support the development of specific and universal vaccines that can quickly treat infection in people to prevent another pandemic,” Dr Walzer advised.
“The cost of inaction is already causing major devastation to wildlife,” Dr Walzer pointed out. “As we work to help affected populations recover, we must remain vigilant against the spread of this deadly pathogen to people before it’s too late.”
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