Though the direct unhealthful impacts of the animal industrial complex (AIC) are reasonably well recognised now, the public health impacts of the AIC remain more unknown, even despite having a very large scale of potential impact. Further, it is well recognised that public health issues across all domains, from infectious diarrhoeal illnesses to COVID-19, have disproportionately higher effects on already disadvantaged communities. In this way, dismantling the AIC is vital in a fight for a just world for human animals, as well as non-human animals and the environment.

Foodborne Illnesses

Foodborne illnesses, which occur following the ingestion of contaminated food or water, contribute to a large burden of infectious disease around the world. One in ten people will suffer from a foodborne illness every year, and 40% of the disease burden can be attributed to illness in children less than 5 years of age. Further, foodborne illnesses disproportionately affect low income countries, where there is often limited access to both clean water and medical care.1

Foodborne illnesses are most commonly caused by pathogenic enteric bacteria that originate from livestock. Indeed, where vegetables or grains have been identified as the culprit behind a foodborne illness outbreak, it is most commonly through contamination from the waste of livestock.2 This can be demonstrated by considering the top bugs that contribute to the global foodborne illness disease burden3:

PathogenNatural reservoirLikely mechanism of transmissionBurden of foodborne illness
Non-typhoidal Salmonella spp.Intestinal tract of the animals such as farm animals, humans, birds, reptiles, and insects.4– Consumption of animal products with Salmonella bacteria present – particularly poultry and eggs.
– Contamination of other food products through run-off from animal farms into soil and waterways, which is then consumed.
– Contamination of packaging of animal products with Salmonella, which leads to contamination of packaging of other food products in contact with it.4
12.4%3
E. coliIntestinal tract of humans and many animals – primarily cattle, sheep, goats, horses, dogs and deer.4– Transmission through direct contact with animals who have the bacteria (eg. farm workers), which can then be further propagated through human-human transmission.
– Consumption of animal products with E.coli bacteria present – particularly milk and beef.
– Contamination of other food products through run-off from animal farms into soil and waterways, which is then consumed.
– Contamination of animal product packaging with E.coli, which leads to contamination of packaging of other food products in contact with it.4
15.3%3
NorovirusHumans. Other strains are found in farm animals, companion animals and wildlife – however it is unclear whether transmission from animals to humans can occur/cause disease.5– Contamination of food and water by a person infected with norovirus.
– Consumption of contaminated food and water by other people.
– Contamination of surfaces/environment through contact from an infected person.
– Transmission to other people through contact with contaminated surfaces.6
7.6%3
Campylobacter spp.Intestines of warm-blooded wild and domestic animals, birds and humans – particularly poultry, cows, goats, sheep, wild birds, cats, dogs and rodents.4– Transmission through direct contact with animals who have the bacteria (eg. farm workers)
– Consumption of animal products with bacteria present – particularly poultry, milk and beef.
– Contamination of other food products through run-off from animal farms into soil and waterways, which is then consumed.
– Contamination of packaging of animal products with Campylobacter, which leads to contamination of packaging of other food products in contact with it.4
6.5%3
Vibrio spp.Humans and marine environments – usually brackish water.– Consumption of contaminated foods – usually undercooked seafood.
– Cross-contamination from contaminated seafood to other foods in the food preparation process, which are then consumed.
– Exposure of open wound to water contaminated with bacteria.
5.2%3
Shigella spp.Humans– Direct human-human transmission.
– Contamination of food and water by a person infected with bacteria.
– Consumption of contaminated food and water by other people.
– Contamination of surfaces/environment through contact from an infected person.
– Transmission to other people through contact with contaminated surfaces.6
3.8%3

As can be seen from the table, many pathogens that contribute to the biggest burdens of disease within foodborne illnesses are those that have reservoirs in farm animals. Though some bugs also have reservoirs within humans and wildlife, and therefore can also develop and be spread without any involvement of farm animals, it seems fair to say that breeding into existence such a large biomass that has the potential to harbour and transmit disease is simply irresponsible, especially in a world where it has never been easier to consume a diet free from animals and their products.

It is worth noting that though most of the disease burden from foodborne illnesses comes from diarrhoeal diseases, there are foodborne illnesses that can cause a variety of serious systemic diseases. As with diarrhoeal illnesses, many of these also originate from animals.3

As well as the AIC contributing to the wider public health safety issue of foodborne illness outbreaks, research indicates that communities in areas of industrialised agriculture are at higher risk of contracting foodborne illnesses of animal origin.7, 8 As these communities are often also systemically disadvantaged in a number of ways, the presence of an industry that worsens health disparities disproportionately is also inherently an issue of environmental injustice.

Pandemics

Foodborne illnesses that have an animal origin are part of the wider group of diseases that have been transmitted from animals to humans, known as zoonoses, or zoonotic diseases. In our current world, they have gained notoriety for being a common cause of pandemics, including the Ebola, SARS, MERS and COVID-19 pandemics. Still other zoonotic diseases have caused famous global epidemics, such as HIV/AIDS.

Indeed, according to the World Health Organisation, 75% of emerging infectious diseases are zoonotic in nature.9 Though they have found their way from animal reservoirs to humans in a number of ways, most of the time there is a shared theme of humans encroaching on wild animal territory, leading the pathogens to spread from a wild animal to either a domestic animal being raised for food, or directly to humans, mutating slightly along the way. Research indicates that while traditional methods of zoonotic disease transmission such as wildlife hunting/consumption and backyard farming have always existed to some degree, the rate of emergence of zoonotic diseases has been increasing since the industrialisation of agriculture. In fact, since the 1940s, agricultural drivers have been associated with the emergence of over 50% of zoonotic diseases in humans.10

While it is true that in industrialised animal agriculture systems farm animals are less exposed to the natural environment and wildlife, and so subsequently less likely to catch a pathogen from a wild animal, due to the nature of the way industrialised farm animals are raised, en masse and in confinement, it means any disease that does enter their environment spreads and mutates rapidly. In other words, industrialised agriculture likely leads to less frequent, but more serious, zoonoses – with an ultimately net negative effect. Further, given the huge amount of waste livestock produce, and the run-off contamination this causes to soil and waterways, zoonotic pathogens that form reservoirs in farm animals can spread quickly, not just to farm workers, but also to entire communities. Given the globalisation of our modern world, infected communities can rapidly develop into an infected nation, and then an infected world – as we have seen with COVID-19.

As well as farm animals being direct vectors for disease, other effects of the AIC, such as deforestation and biodiversity loss, also indirectly lead to the spread of pathogens from wild animals.10 It is important to note zoonotic diseases are not always transmitted through close contact to animals or consumption of animal products – for example, vector-borne illnesses, such as malaria and Zika virus, are both transmitted via mosquitos. For this reason, eliminating zoonotic diseases will not be as simple as just no longer farming animals. However, it is widely recognised that decreasing the ways in which we encroach on wild animals and concentrate domestic animals are both key strategies in the prevention of global infectious disease pandemics. 

Antimicrobial Resistance

Imagine if a cut on your leg required amputation of the whole limb, or a simple urinary tract infection could cause death; this would be a world without antibiotics. It is for this reason that antimicrobial resistance has been labelled by peak health bodies around the world as one of the major threats to global health.11 Antimicrobial resistance refers to the phenomenon whereby microbes become resistant to antimicrobial therapies, most famously antibiotics, through a process of natural selection (similar to how humans and other animal species have evolved to favour pro-survival characteristics over time). In this way, antimicrobial resistance is inherently linked to antimicrobial overuse, as the more antibiotics are used, the more chance of microbes developing resistance.12

It is now reasonably well known that antimicrobials are overused in human medicine, and these days doctors are trained in what is known as “antimicrobial stewardship” – essentially the practice of using but not abusing antimicrobials. It is less commonly known that antimicrobials are also overused in animal agriculture, and in much larger amounts than those that humans consume. It is estimated that up to 80% of the world’s antibiotics are used in livestock – mainly poultry, pigs and cows.13 Of these, most are antibiotics commonly used in humans, which is where the concern regarding transferrable antimicrobial resistance to humans arises.14

The mechanism by which antimicrobial resistance occurs in all animals (including humans) is that microbes that inhabit the animal (whether pathogenic or commensal) develop resistance to the antimicrobial agent when it is administered, and then this resistant microbe is transferred either directly or indirectly to other animals. In regards to livestock who harbour microbes that develop resistance due to the large quantity of antimicrobials used, these can be transferred to humans through direct contact (eg. farm workers), consumption (eg. consumers of contaminated products) or indirectly through contact with contaminated environments (eg. bodies of water contaminated by faecal run-off from farms).15 Indeed, it has consistently been shown that animal farm workers have higher rates of resistant gut bacteria compared to the general public, or even compared to workers on farms that do not use antibiotics.14 Similarly, faecal contamination of soil and waterways by livestock waste harbouring resistant microbes, and it’s potential as a route of transfer to humans, has also been demonstrated.16, 17

Further, it is estimated that 50-90% of antibiotics are excreted by farm animals either completely or partially unmetabolised. This means that microbes in the soil are also exposed to antimicrobials and can subsequently also develop resistance.18 Though some level of antimicrobial resistance will always exist in our dynamic biological world where “natural variants” are present, the rate of antimicrobial resistance we are seeing, particularly since the industrialisation of agriculture, is increasing so rapidly that we cannot keep up with creating new drugs to tackle these “super-bugs”.11 What we know for sure is this: an increase in use of antimicrobials, whether in humans or animals, will increase the rate of antimicrobial resistance. Some regulatory bodies around the world, such as in the EU and US, have tried to curb the amount of antimicrobials used for livestock by banning the practice of using them as growth promoters.19 However, the reality is that, as long as farm animals grossly outnumber humans, more antibiotics than we can comprehend will be used to treat or prevent illnesses in farm animals for the sole purpose of raising them for humans to consume.

Given that a reduction in all antimicrobial use, whether in human animals or non-human animals, is the only way to tackle the global threat of antimicrobial resistance, we must ask ourselves if we can justify any use in farm animals, especially in a world where it has never been easier to consume a diet free from animals and their products. The AIC contributes to a number of public health threats, and with numbers of farm animals projected to continue increasing as industrialisation becomes more widespread, without intervention these threats are only going to continue to grow. The fact that these public health issues disproportionately affect those who are already disadvantaged provides even further incentive to dismantle this system that is built upon oppression.

Conclusion

If COVID-19 has shown us anything, it is what we can do when we are united. Kindness, respect and consideration for our communities are the reasons why we endure lockdown. It is not so hard to extend these values to include the greater non-human world around us, and may end up having vast benefits for humans in the process.

References

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