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Factory farming is fuelling a ‘silent pandemic’. Here’s what we can do about it

Antibiotic use on factory farms is affecting human health.
Antibiotic use on factory farms is affecting human health. Copyright AP Photo/John Locher, File
Copyright AP Photo/John Locher, File
By Nichola Daunton
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Antimicrobial resistance could cause 10 million deaths per year by 2050. Here’s what can be done about it.


As the world recovers from COVID-19, and bird flu decimates wild and farmed birds, the link between food production and pandemic risk has never been clearer.

From zoonotic diseases (those transmitted between animals and humans, through direct or indirect contact) to antimicrobial resistance (AMR) our industrial food systems are creating a breeding ground for viruses and bacteria.

While encroachment into wild habitats is leading to some spillover events, with viruses spreading directly from animals to humans, many of the current viruses of concern, such as avian flu, are being exacerbated by factory farming and the close, cramped conditions that animals are kept in.

So how is our current food system increasing the likelihood of another pandemic? And what can be done to reduce the risk?

To find solutions to these problems, Compassion In World Farming recently hosted scientists, policymakers and delegates at a  a two-day conference in London. The  Extinction or Regeneration conference saw speakers discuss how current food systems can be changed to make farming and agriculture more sustainable, ethical and eco-friendly, while feeding a growing world.

Antimicrobial resistance: The silent pandemic

Often referred to as ‘the silent pandemic’, according to the World Health Organization (WHO), antimicrobial resistance occurs when bacteria, viruses, fungi and parasites evolve to resist the antibiotics used to treat them. This resistance makes diseases much harder to treat and increases the risk of their spread.

AMR can happen when antibiotics are overused, as the bacteria that develop resistance are able to multiply. Giving antibiotics in low doses can lead to AMR too, as the bacteria being treated are not destroyed and may go on to develop resistance.

“If some of the bacteria have developed resistance,” explains Cóilín Nunan, scientific adviser at the Alliance to Save Our Antibiotics who spoke on a panel dicussing health and diets, “then these bacteria are unaffected by the antibiotic and can continue to proliferate, spreading from human to human, or from animal to animal, or from animal to human.”

How are antibiotics used in farming?

The first antibiotic, Penicillin, was discovered by Alexander Fleming in 1928. In his 1945 Nobel prize speech, Fleming warned of the risks of administering low doses of the drug. But just four years later, scientists in the US discovered that feeding low doses of antibiotics to animals promoted growth, and antibiotic use escalated.

Antibiotics were also used on a mass scale to prevent diseases in healthy animals, often as a result of poor hygiene and overcrowding, as Cóilín explains.

Food systems very often rely on excessive and routine antibiotic use, particularly when animals are kept very intensively, because disease can spread a lot more easily. When animals are kept indoors in high numbers, diseases spread in a very similar way to how they spread in humans.”

Though the EU banned the use of antibiotics for growth promotion in 2006, it is estimated that 66 per cent of all antibiotics used are still given to farm animals, not humans. Though most AMR is still linked to human use, as Cóilín highlights.

“Most antibiotic resistance in human medicine is actually due to the human use of antibiotics. However, there is clear evidence that the farm use of antibiotics is also contributing, not just to antibiotic resistance in farm animals, but also to infections in humans.”

How is antibiotic use on factory farms affecting human health?

“When animals are fed antibiotics, some of the bacteria may develop resistance and so they can end up with resistant bacteria in their guts,” explains Cóilín.

“And then at slaughter, some of the bacteria will end up contaminating the carcass and when that meat is handled, or if it's eaten when it's undercooked, any bacteria that are still alive can spread to humans and ultimately cause resistant infections.”

While this is quite a direct form of transmission, bacteria can also enter the food system in less direct ways too. Farm animals excrete antibiotics through their urine, which then ends up in slurry and manure. This manure is then spread on agricultural land, to help fertilise crops, “so you can end up with resistant bacteria on crops, some of which are eaten raw,” says Cóilín.

Thanks to the pressure from groups like The Alliance to Save Our Antibiotics though, change is starting to take place. In January 2022 the EU banned all forms of routine antibiotic use on farms, including preventative group treatments. The use of antibiotics to compensate for poor husbandry - breeding and care - or poor hygiene was also banned.

“In theory, that's a very radical position,” says Cóilín, “because a lot of antibiotic use is actually to compensate for poor hygiene and husbandry.


“When you have 30,000 or maybe even 50,000 chickens in one shed, and each chicken has less than an A4 sheet of paper in terms of space, then you inevitably have very bad hygiene.”

In the UK, similar legislation is currently out for consultation. Though the UK government is planning to adopt many of the same laws as the EU, there are concerns that some key aspects will be left out.

The good news though is that use of antibiotics on UK farms has fallen by 55 per cent since 2014, though the use of antibiotics in aquaculture is sadly on the rise.

Michael Macor/San Francisco Chronicle via AP
Viruses are being exacerbated by factory farming and the close, cramped conditions that animals are kept in.Michael Macor/San Francisco Chronicle via AP

What needs to change?

Ultimately, says Cóilín, better animal husbandry is the solution to farming’s over-reliance on antibiotics.

“There are a wide range of improvements that could be made, such as lowering the stocking densities per square metre, giving animals more space, improving hygiene and weaning piglets when they're a bit older, so that they are less stressed and their gut bacteria are more developed.”


These changes are crucial if AMR is to be controlled. Currently, it is predicted that AMR will cause 10 million deaths per year by 2050, while bacteria resistant to the antibiotic of last resort, Colistin, was found on British farms in 2015.

“Some of these husbandry changes are going to be needed if the law is going to be respected and if we’re going to protect antibiotics, because we need to bear in mind there is a huge cost to antibiotic resistance.”

But what about zoonotic diseases?

While AMR is a growing threat, almost all of the recent pandemics have been caused by zoonoses, explains Melissa Leach, Director of the Institute of Development Studies who spoke on a panel dicussing the impact of the global food system on human, animal and planetary health.

“Our current food systems are rendering us vulnerable to the spillover of diseases that are harboured by animals, which risk spilling over to affect people.”

While pinpointing the exact spillover event can be difficult - as COVID-19 has proven - there are generally three main pathways through which diseases can transfer from animal to human populations, both directly and indirectly.


Habitat and biodiversity loss

The destruction of wild habitats and biodiversity loss can lead to animals encroaching on human spaces in order to find food or shelter.

In the right circumstances this can lead to direct transmission of viruses from wildlife to humans, “which is what some people think we saw with the Ebola virus disease, for instance, or Nipah virus, which has been a big problem in South East Asia,” says Melissa.

“This really happens where you get loss of biodiversity…You can end up with very impoverished landscapes and the kinds of animals that are left are often the ones which share viruses with people.”

With global biodiversity plummeting at an alarming rate - there’s been a 69 per cent decline in species populations since 1970 according to the WWF Living Planet Report 2022 - the situation is likely to grow worse unless habitats are restored.

Industrial livestock systems

Perhaps one of the biggest vectors for disease though is the current livestock system. The way that animals are crammed together, often with little individual space and poor air circulation make factory farms the perfect breeding ground for disease.


“Large scale, high intensity animal farming, produced to reduce meat prices globally has left us vulnerable to all kinds of diseases,” says Melissa.

“The animals themselves become more susceptible to viruses because they’re in close quarters and they often have very low genetic diversity.”

Any diseases that develop then risk spilling over to farm workers, Melissa explains, and may spread to wildlife hosts at local markets, before crossing back to human populations, as some believe happened with COVID-19.

Trade routes

While factory farms may act as the breeding ground for pathogens, food trade routes can quickly spread them around the world. Trade routes often occur over very long distances, with animals confined to close quarters.

“It’s part of the reason why microbes have become so mobile and why you have the risk of a spillover and an outbreak into one place spreading to affect the whole world.”


How can we protect ourselves from future pandemics?

While Melissa believes that another pandemic is inevitable, she thinks preparedness is key to protecting society from the worst effects.

“We really need to make sure that all countries have a really good social protection system in place that can be mobilised to provide food assistance and cash assistance if we get another major, major pandemic,” she explains.

“I'm really making the argument that transforming food systems to be more pandemic proof also involves transforming power relations. And that is not easy. It takes pressure from all sides and it takes commitment to reform from above.”

You can find out more about the Extinction or Regeneration Conference here.

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