Photo: Mads Claus Rasmussen/AP
What would you do if you wanted to kill as many people as possible, unmistakably and without criminal consequences? You would do well to start with a bird flu. Bird flu is responsible for all known flu pandemics: the big flu that started more than a century ago, the “Asian flu”, the “Hong Kong flu” and the “Russian flu”, which together killed tens of millions of people. They also cause many of the annual outbreaks that kill hundreds of thousands of people.
Once you’ve found a suitable variant, two more components are needed to weaponize it. The first is an amplifier. The best amplifier is a giant barn or factory in which thousands of birds are packed. These birds must be genetically homogeneous so that your virus strain can travel freely between them. Intensive poultry farms would come in very handy. Before long, a low pathogenic strain should mutate into a highly pathogenic variety under these conditions.
To ensure maximum transmission, move a number of birds faster than the incubation period of the flu. You could transport them across the border. Some would be moved to free-range or hobby farms to increase the chance of wild bird infection.
But it’s difficult for a flu virus to pass directly from birds to humans, so another component is needed: a mixing vessel. This is a species that can simultaneously harbor the newly pathogenic avian virus and a flu variant that has already been adapted to humans. Then, conveniently brought together, the viruses can exchange genetic material – a process known as “rearrangement”.
Pigs are reasonable mixing vessels. They may have played this role in previous outbreaks and pandemics. But there is a much better candidate: mink. Mink easily harbors human and bird flu viruses. As predators, they can easily contract bird flu from the meat they eat. The distribution of sialic acid receptors – a major determinant of infection – in their airways is similar to that of humans. Human flu strains can pass between them via aerosol transmission.
Minks also possess, to a remarkable degree, what scientists call “zoonotic potential”: in other words, they can be infected by and infect many different species. During the early stages of Covid-19, they proved to be very effective intermediaries, partly because the virus seems to evolve faster in mink than in humans. They appear to have generated at least two new variants that have spread to humans, one in Spain and one in Italy. Minks are the only known species to have both received and passed on Covid-19 from humans.
To improve their mixing ability, cram together hundreds or thousands of the small cages they are in, forcing this usually solitary animal to interact with others. You would reduce genetic diversity by breeding only those with a certain coat type. In other words, you would do what mink farms do today. Then you would sit back and wait.
The next pandemic may not have spread from a homicidal psychopath, but unless we’re lucky, the effect could be the same. H5N1 was a fairly harmless bird flu until a highly pathogenic variant was hatched in 1996 in a Chinese goose farm. It is deadly to humans. In the rare cases that people have contracted this variant, it has more often than not proved fatal: of the 868 infected up to October last year, 457 have died. Although it has been devastating to poultry flocks and wild birds alike, the transmissibility from birds to most mammals and from human to human is thankfully extremely low.
But mink farming provides the mixing vessel it needs. In 2021, a paper in the journal Emerging Microbes & Infections reported that about a third of the minks the researchers tested had both avian flu and human flu antibodies. It warned that this joint infection could generate new viruses “with high human infectivity”. The threat to public health “should not be ignored” as it had “pandemic potential”. Needless to say it was ignored.
A few days ago, the journal Eurosurveillance revealed the first known case of large-scale transmission of the H5N1 influenza virus from mammal to mammal. It happened, to no surprise, on a mink farm; in Galicia, northern Spain. While the minks were fed poultry products, a practice scientists have long warned against, it appears the likely cause of infection was contact with a sick wild bird that may have fallen against the bars of a cage and been dragged through and eaten . Once in the mixing vessel, the virus mutated to become transmissible to the other minks, then quickly spread from cage to cage in this farm of more than 50,000 animals.
This epidemic was under control before it left the farm. All minks have been killed and we may have just missed a pandemic potentially deadlier than Covid-19. But the breeding of minks for their fur, a cruel and pointless practice, continues in Europe, North America and China. Chances are the next pandemic, whatever it may be, will break out in one of these places. Because of both the appalling cruelty the animals endure and the serious threat it poses to human life, we need a global treaty to ban mink farming.
The H5N1 virus, which acquired its deadly mutations on a poultry farm, is now rampaging through wild bird populations with horrific consequences. It kills so many that, when combined with other threats, it could drive some species to extinction. In particular, it shatters colonies of seabirds. Because they reproduce late and slowly, they are particularly vulnerable to extinction. Wild birds could easily introduce the virus to another mink farm.
Related: Bird flu is now a huge problem – but we are only one mutation away from a much worse situation | Devi Sridhar
This threat is offset by grotesque brutality: the poultry, mink, and pig farms whose horrors we have somehow normalized and accepted. If you treated dogs or cats the way we treat these animals, you would be sent to prison. But do it with cultivated strains on a large enough scale and you’ll be treated with the special respect accorded to a “captain of industry”. Governments will sweep the dust from your path. Newspapers will write eulogies of the sort once bestowed upon emperors.
So who is the homicidal maniac in this story? It’s a barely explored abstraction we call “the economy,” a monster to whom anything and everything must be sacrificed without question or opposition: farm animals, wild animals, even, unless we’re lucky, millions of people. We can only prevent the pandemics of the future if we value life over money.