Bird flu, or H5N1, has scientists and conservationists rattled. The current variant, which has been circulating among birds globally since 2020, is more deadly and spreading more rapidly than previous mutations of the virus. Some people have died after contracting it from birds, but so far no sustained human-to-human transmission has been identified.
Infections are also shifting from seasonal to year-round, and having a far greater impact on wild birds, according to a study by scientists at the University of Maryland. Its authors concluded that H5N1 will probably become endemic in the US, as it likely already is in Europe, and warned of risks to food security and the economy.
“This high pathogenic virus is wiping out everything in numbers that we’ve never seen before,” said Jennifer Mullinax, an assistant professor at the University of Maryland and a co-author of the study.
H5N1 viruses primarily infect domestic poultry, where they emerged, and wild birds. They have already had a devastating effect on wild bird populations. In the UK, conservationists have warned that bird flu could put the great skua at risk of extinction.
However, the viruses have also infected mammals, including badgers, black bears, bobcats, coyotes, dolphins, ferrets, foxes, lynx, minks, otters, pigs, polecats, raccoons, seals and skunks. In March 2023 alone, 3,487 sea lions died from the virus in Peru – equivalent to 3.29% of the population there.
Transmission between mammals has been limited, according to the World Health Organization (WHO). However, one outbreak has particularly worried scientists. In October 2022, mink on a farm in Galicia, Spain, started dying in higher than normal numbers. H5N1 had spread among the almost 52,000 animals, which were housed in 30 barns.
All the mink were culled over the next month. Farm workers were quarantined, and none tested positive for bird flu. Scientists studying the outbreak cited infected wild birds as the possible cause because the mink farm is partially open, and though there had been H5N1 cases in the region, it had not been found at poultry farms that provided food for the mink.
Mink are particularly under the spotlight because they are highly susceptible to human and avian flu viruses. Farmed for their fur, the animals are typically kept in crowded barns, increasing the risk of transmission. And their genetic similarity raises the risk of mutation. In short, mink appear to be particularly well placed as the species in which H5N1, currently mostly in birds, could mutate to be far more deadly to humans.
The risk was laid bare during the Covid-19 pandemic, when widespread outbreaks of the virus in mink farms demonstrated that not only did it circulate widely among mink, but also mutated and then spread back to people.
Regarding bird flu, only six people have so far been reported as having had the current strain, all caught from direct exposure to infected poultry. Four were from Europe and North America, and had no symptoms or only mild clinical signs, but two from Asia had severe symptoms and died, according to the WHO.
Analysis of the H5N1 viruses from the Spanish mink farm has not found any indications that would point to increased ability to infect humans, according to Dr Tim Uyeki, chief medical officer of the influenza division at the Centers for Disease Control and Prevention, a US public health agency.
An update by the agency in March confirmed that 10 people globally have contracted HPAI A(H5N1) since January 2022. Hundreds have died from H5N1 overall since 2003, and all were infected after coming into contact with poultry.
H5N1 viruses are not currently able to easily infect the human upper respiratory tract, which would be needed to increase the risk of transmission to people, Uyeki explained. The threat to human health depends on whether there were any genetic changes in the virus, and how these compared to existing H5N1 viruses circulating in birds, he added.
“While there was a genetic marker in the H5N1 viruses detected during the outbreak in mink in Spain that may have increased the amount of virus in infected mink, this marker is unlikely to make it easier for H5N1 virus to transmit to humans,” he said.
Humans lack the type of cell receptor in the upper respiratory tract that H5N1 viruses use to cause infection, he explained.
According to the WHO, the risk of infection for humans currently remains low and no sustained human-to-human transmission has been reported. However, it said it was continuing to monitor the situation alongside the UN’s Food and Agriculture Organization and the World Organisation for Animal Health (WOAH).
Nevertheless, some believe that the time is now right to ban mink farming globally. A growing number of countries have already outlawed the practice due to animal welfare concerns. Farmed mink are kept in tiny cages, which has led to eye and ear infections, deformed feet, repetitive pacing indicative of mental decline, and cannibalism, according to Humane Society International (HSI).
Momentum for a ban accelerated during the Covid-19 pandemic, which saw mass culling of farmed mink. In Denmark in particular, more than 15 million mink were exterminated after the virus was found to have mutated in 200 mink farms.
“One of the few positive things to come out of the Covid period is an awareness of the consequences of intensively keeping animals,” said Joanna Swabe, senior director of public affairs for HSI in Europe. “Secondly, it has actually accelerated the decline of the fur industry.”
It will be very inconsistent if they stop people keeping chickens and pigs in cages, but still allow animals to be kept in tiny cages for furJoanna Swabe
So far, 19 countries across Europe have banned the practice. It is still allowed in Finland, Poland, Greece, Lithuania, Spain, Romania, Sweden, Denmark and Bulgaria, but the industry is in decline. The number of animals killed for fur in European countries had already fallen from 43.6 million in 2014 to 30.7 million in 2019 before the pandemic; by 2021 it had declined further to 12 million animals, according to HSI. Some 1,500 retailers, including Gucci, Adidas, H&M and Zara, have committed to eliminating use of fur.
Moves are underway for an outright ban at EU level. The European Commission is drafting legislative proposals to update and expand the scope of EU animal welfare legislation as part of its farming strategy, which campaigners argue is the perfect opportunity to include a ban on the fur trade across the EU.
A petition urging a ban, organised by animal rights campaigners, was signed by more than 1.7 million EU citizens, exceeding the number required for the commission to respond. Swabe was confident the campaign to abolish fur farming in Europe would succeed as the commission had already committed to end caged confinement for farmed animals.
“It will be very inconsistent if they stop people keeping chickens and pigs in cages, but still allow animals to be kept in tiny cages for fur. That’s not consistent and it’s not going to go down very well – they know which way the wind is blowing,” she said.
The situation is less clear in the US, where there is little regulation of fur farming, and submission of data to the US Department for Agriculture is voluntary. Bills have been introduced in Washington and Oregon to end fur production, but they failed to pass. An attempt by some animal protection groups to have farmed mink listed as “injurious” under the Lacey Act also failed. That would have prohibited the import and transport of live or dead mink and their parts, including fur, according to PJ Smith, director of fashion policy at HSI in the US.
An attempt was made to introduce a federal bill to abolish fur farming in 2021, but new proposals are in the offing that would introduce a buyout program to help mink farmers transition to alternative activities, Smith said.
Mink farming is also significant in China. In early 2020, China announced a complete ban on the consumption of terrestrial wild animals as food – including captive-bred wild animals – and a crackdown on the illegal wildlife trade. However, the ban did not cover non-food uses of wild animals, leaving farming for purposes such as fur and traditional medicine largely unaffected. Moreover, mink and several other species (including foxes and deer) used for fur and medicine were subsequently reclassified as “livestock” meaning they now fall outside the purview of China’s Wildlife Protection Law, and any farming restrictions imposed under it.
Despite the continuation in some parts of the world of the farming of mink and other animals for fur, there have been scant attempts to bring the issue of wildlife consumption and trade into international agreements on pandemic preventions, including regarding a treaty currently under negotiation.
Discussions so far have mostly focused on outbreak surveillance, containment and response, rather than avoiding zoonotic (that is, animal-to-human) spillovers in the first place, according to a paper published in the Lancet Planetary Health.
Its authors urged a shift of focus to preventing such spillovers, since containment of outbreaks would become unfeasible given the acceleration of globalisation. The treaty should be “explicit about zoonotic spillover prevention and focus on improving coordination across four policy domains, namely public health, biodiversity conservation, food security, and trade”, it said.
Christian Walzer, executive director of health at the Wildlife Conservation Society said that the global community should collaborate to end fur farming. Ultimately, health should be viewed as a global good, he said.
“Health is not a cost, it’s an asset. We need to change the narrative. In a global context, we simply can’t afford to keep farmed mink, when we know they’re highly susceptible [to] groups of viruses which have pandemic potential,” he said. Since the demand for fur is dropping anyway, it really makes no sense to keep producing it, he added.
Swabe echoed these sentiments. Mink farms represent “a recipe for disease transmission”, she said. “Covid will be nothing compared to avian influenza if it took hold in human populations, so having populations of animals in captivity whose only purpose is to provide pelts for luxury products – is it worth the risks to human health and the health of the species that we keep for food?” she said.