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Covid-19 mink mutation casts light on intensive farming

A couple of weeks ago, Denmark decided to kill all its mink. All 17 million of them.

Mink culled in Denmark after testing positive for a mutated form of Covid-19. Source: Associated Press

By rnz.co.nz’s The Detail

The mink had tested positive for a mutated form of Covid-19 after catching the disease from humans.

Two million went to the slaughterhouse before the cull was paused, with opposition parties objecting, and questioning the constitutionality of the decision.

Culls of animals suspected of carrying an infectious disease are no new thing - here in New Zealand, more than 100,000 cattle have been slaughtered to halt the spread of mycoplasma bovis.

But there are more than 800,000 animal-borne viruses which could be passed on to humans - and the more we push into as-yet untouched parts of nature, the greater the chances of those diseases becoming pandemics - much like HIV, Ebola, Covid-19, and many more diseases which originated in animals.

Today on The Detail, Emile Donovan speaks to Newsroom.co.nz political reporter Marc Daalder and infectious disease expert Professor David Hayman about what this pandemic has taught us about our relationship with nature, and how can we utilise those to mitigate the next pandemic when it inevitably surfaces.

First things first - Covid mutations aren't quite as scary as they sound.

"Our pop culture understanding of viruses [suggests] they become worse, or stronger ... [but] mutation is normal. The flu virus mutates frequently and quickly, which is why you have a new flu vaccine each year,” says Daalder.

"The coronavirus mutates less frequently than the flu - on average about 24 times per year. And any one mutation is generally not cause for concern."

Still, mutations can lead to complications: if a disease mutates considerably, it can neuter the effectiveness of a vaccine. Because we haven't yet approved a functional vaccine for Covid-19, we want the disease to stay as inert as possible while we continue to work on one.

It's not entirely surprising that the virus mutated in mink farms, says Massey University infectious diseases expert David Hayman.

Mink are farmed commercially for their fur in many European countries, and kept in close proximity - much like other forms of intensified farming.

Animals being kept in such close quarters provide perfect conditions for a virus to spread en masse - and Hayman says this example should lead us to think more carefully about how humans use animals.

As you clear natural animal habitats to use that as farmland, “you're moving both people and domestic animals into space where there were wildlife, and you're increasing the chances of contact between domestic animals and wildlife ... they can act as a reservoir, an interface, where an infection goes from wildlife into domestic animals, and then passed on to people.

"But [it's also worth considering] the intensification of agriculture itself: you're having very genetically similar animals that are potentially stressed, in high densities. These are perfect populations for viral infections to spread."

Listen to The Detail on rnz.co.nz (funded by NZ On Air)