A common conspiracy among teens in the United States, mostly in jest, is that birds are not real. The story goes like this: between 1959 and 1971 the United States government replaced every living bird with a drone. Up to today, these sinister agents spy on American citizens, recharge on power lines, and use their excrement to track automobiles of interest. As these things tend to go, the conspiracy is untrue. However, there are indeed 9.5 billion birds whose existence is actively supported by the United States Government and whose presence represents a substantial threat to the health and well-being of American citizens. These are the 9.5 billion chickens in the United States being raised for meat and eggs.
The problem with chickens is not that they operate as agents of the deep state, but rather the incredible burden of disease that comes along with the current system of fowl-based agriculture. Chickens represent a particular threat, but the pork and beef industries are also riddled with insecurities. Collectively, animal agriculture exposes the United States, and all other participating countries, to a higher burden of disease. Zoonotic diseases, meaning diseases transmitted-by or originating-in animals, represent 50% of all active pathogens and 75% of recently emerging pathogens.[i] These diseases are driven by human-animal contact, including between domestic livestock and farm workers. Some of the most famous zoonotic diseases, such as Malaria, are primarily transmitted by wild animals but are indirectly linked to animal agriculture. Alongside the threat of zoonotic disease, animal agriculture has accelerated the problem of antibiotic resistance.
Together the emergence of new diseases and the weakening of antibiotics are major unaddressed externalities of animal agriculture.[ii] They impose potentially enormous costs on society, but they are not reflected in the price of a chicken breast or a box of nuggets. In fact, many governments perversely and actively subsidize animal agriculture. The objective of this article is to (1) outline the disease burden of animal agriculture and (2) point out some of the ways the situation might be improved through policy. The focus is on the United States, though the contours of the critique are applicable to most governments in the developed world today.[iii]
It is first important to understand just how big a problem zoonotic disease can be. The 1918 influenza pandemic, which killed more humans than any other disease in world history, began in birds. The Bubonic plague, which killed the largest percentage of the global population, is spread by rats and fleas. HIV/AIDS, the deadliest ongoing pandemic, began in monkeys and likely leaped to humans through the consumption of bushmeat. And of course, COVID-19 famously moved from bats to humans, probably via a wet market in Wuhan. For every case of viral explosion, there are many incidents that impose major costs without rising to the level of catastrophe. Major bird flu epidemics in 1957, 1968, 1977, and 2009, collectively killed around 5 million people. The last of these is often remembered as a “swine flu” because it moved from birds to pigs and then to humans. Pigs act as excellent petri dishes for zoonotic diseases. They pick up pathogens from animals that are physiologically quite distinct from humans, such as chickens, then after incubating in pigs, these pathogens can hop to human populations. This points to the dark synergy between different forms of animal agriculture.
Currently, an H5N1 bird flu is emerging in the United States, and we appear to be asleep at the wheel.[iv] Beginning in January of 2022, the Centers for Disease Control (CDC) became concerned with the spread of bird flu in poultry which has since spread to at least 136 million birds. In the past year, the disease has begun to noticeably affect large swaths of cattle, causing symptoms from reduced milk production to spontaneous abortions. This bird-to-mammal transmission is a harbinger of the risk of a leap to humans.
There have been several dozen cases of human H5N1 in North America but so far only one death, and the disease does not yet appear capable of spreading from human to human. Still, historically, H5N1 has had an exceptionally high case fatality rate with half of reported human H5N1 infections being fatal. Juan Cambeiro, of the Institute for Progress estimates a 5% chance of a pandemic as bad or worse than Covid-19 as a consequence of the current outbreaks. While this chance is low, it is important to remember that this is not an isolated incident. Every year, somewhere in the world, new zoonotic flus like H5N1 are cropping up in animal agricultural systems. It is as if every year the human species were rolling a pair of dice, and if the dice both show sixes there will be a major epidemic or pandemic. The only reasonable policy is to stop gambling.
Animal agriculture also acts as an important cause of disease in indirect ways. Clearing rainforest for pasture or damning rivers for grazing disrupts ecosystems. In fact, the number one cause of deforestation is animal agriculture, both because of forest cut down for grazing and for growing the crops which feed livestock. This leads to a reduction in biodiversity and more interaction between wild animals and the human world. Therefore, and perhaps unexpectedly, zoonotic diseases are likely to leap from wild animals to humans because of domesticated animals. This is an issue in all nations, but most prominently in the developing world. The direct and indirect effects mean that collectively animal agriculture is responsible for around 50% of all zoonotic diseases that emerge globally.
Some of the smallest parts of the animal agriculture market produce outsized risks. Wet markets, where many types of animals are sold and slaughtered on site, are ideal locations for disease transmission. While these are often associated with developing countries in Asia, there are eighty wet markets in New York City alone and the number is growing. Mink farms represent a tiny fraction of all farming, but they produce extremely large risks. Minks are unusually susceptible to the flu, and they act as excellent incubators. For this reason, the Netherlands has completely banned mink farms.
A final way that animal agriculture drives disease is by promoting antibiotic resistance. While much antibiotic resistance is driven by improper use of antibiotics in humans, the unnecessary use of antibiotics in animals is much more common. According to a 2019 study, “in the United States, nearly nine times more antibiotics are given to animals than humans and, of the antibiotics given to animals, more than 12 times as many are used non-therapeutically as therapeutically.” Non-therapeutic means that there is no evidence of an active disease, and the antibiotics are simply being used preventatively or to increase growth. This flagrant use of antibiotics has led to dangerous, antibiotic resistant strains of Salmonella, Campylobacter, and Escherichia coli. Similarly, the overuse of deworming medications has led to anthelmintic resistance which exposes humans to more risks from tapeworms and other parasites.
It is hard to quantify just how bad all of this is. There are several sophisticated analyses of the negative externalities which livestock created by contributing to climate change. Studies on disease burden are more sporadic; however, in 2023, the Impact Institute estimated that, “The total impact of diet-related disease resulting from animal sourced food consumption in the EU [is] €452 billion.” Juan Cambeiro’s estimates suggest that the risk of H5N1 alone has an expected cost of $640 Billion.[v] These isolated estimates suggest that the total burden of animal agriculture is extremely large, regardless of the exact quantity. In fact, the estimated costs dwarf the contribution of animal agriculture to GDP which is around €163 billion in the EU and $222.3 billion in the United States.
The human impact behind those numbers should not be underestimated. As everyone now understands, pandemics are responsible for enormous quantities of human suffering. They steal small joys and produce the most profound forms of loss. Antibiotic resistance and rare viruses also create more quotidian losses which occur in more dispersed ways, but these are no less devastating for the individuals impacted. Keeping chicken cheap is simply not worth the risk.
The upshot is that policies to address zoonotic diseases should be much more aggressive. These come in several forms. First, the United States and other nations should stop subsidizing the production of animal products. Meat and dairy producers in the United States receive $38 billion every year in financial assistance. This comes in both direct and indirect forms. Sometimes the intention is to promote cheaper and more abundant meat, other times livestock farmers take advantage of more general subsidies which are available to anyone in the agriculture industry. The problem exists worldwide. Collectively, OECD countries give $53 billion in financial assistance to the meat and dairy industry. Econ 101 is to tax negative externalities, not to subsidize them, and so at a bare minimum these direct and indirect subsidies should end.[vi]
Second, rich countries should disincentivize the use of antibiotics in farming. A recent study found that each kilogram of enrofloxacin used in poultry farming is associated with $2,200 in externalities.[vii] More such studies should reveal the impacts of specific antibiotics and anthelmintics, and then a tax should be levied at the appropriately determined rate. The resulting revenue can go to antibiotic and vaccine research or to the cost of administering disease prevention programs. Further, politicians should consider an outright ban on non-therapeutic uses of antibiotics which would be in line with the recommendations of the World Health Organization.
Third, regular monitoring of both workers and animals should be more common so that zoonotic disease threats can be tracked. Disease types which are judged to occur commonly should result in efforts to develop relevant vaccines. Preventative vaccination of workers and animals should be mandatory or strongly incentivized. In some cases, full bans may be determined to be warranted, such as in mink farming.
This is the most complicated of the three proposals but also the most important. Monitoring relevant populations would mean keeping tabs closer on farm and slaughterhouse workers. Staying in touch with these populations may mean strategically ignoring the sometimes-dubious legal immigration status of livestock workers. It also means creating a stronger epidemiological ground game. Public health agencies such as the Centers for Disease Control and the World Health Organization should employ more epidemiological troops who can be in contact with local communities and alert to threats.
Vaccine development and rollouts should emerge from monitoring efforts. Vaccination remains the closest thing possible to a silver bullet. The development of the Covid-19 vaccine and the recent successes with Malarial vaccinations demonstrate that scientists are capable of more significant and rapid advances than was previously appreciated. Ramping up resources for vaccine development is therefore likely to result in positive outcomes. Observation and vaccination remain the first and best line of defense against the emergence of new diseases. Moonshot possibilities such as universal vaccines are worth taking extremely seriously. A large-scale program of the type required would be costly, but even if it averted a minor epidemic, it would quickly pay for itself.
Psychologically, policymakers are much better at responding to emergent threats than they are at nipping them in the bud. However, a shift toward preventative strategies is imperative. In a very literal sense, we cannot afford to wait until the problem becomes obvious. The birds may not be spying on us, but it is time for us to spy much more closely on the birds.
Endnotes
[i] Zoonotic diseases are a complex topic, and this article barely scratches the surface. Many of the most important zoonotic diseases, such as Lyme disease are mostly not driven by agriculture. I deal with just one type of zoonotic disease here, but they come in many forms and interested readers are strongly encouraged to read the primer at the bottom of the article.
[ii] The other major externality of animal agriculture is its massive contribution to climate change. This likely represents a larger threat than zoonotic disease, though the differences between the two threats make it hard to compare.
[iii] The issues faced in the developing world are equally critical, but they follow different trends and require different solutions.
[iv] As a side note, the H and N in disease names like H5N1 stand for hemagglutinin and Neuraminidase. Thes are proteins which affect the transmission of the virus. Hemagglutinin helps the virus attach to and enter host cells while Neuraminidase helps newly formed viral particles escape host cells. Other relevant examples include H1N1, which spread easily, and H7N9, which has a high case fatality rate.
[v] For possible future events for which damages have not yet occurred, expected value is a useful tool. What Cambeiro’s number implies is that if H5N1 goes pandemic level if will have an economic impact of around 12.8 trillion dollars. However, since there is only a 1 in 20 chance of that occurring, the expected value of the cost is $640 billion.
[vi] I would also strongly support a higher tax on meat and dairy products at the point of sale in grocery stores and other markets; however, I understand that this is radically unpopular.
[vii] This includes obvious economic costs but also attempts to put a dollar amount on certain human costs. Monetizing human impacts is obvious complicated, and it often relies on complexly derived metrics like QALYs (quality adjusted life years). There is a large and thriving literature on how to do this in a way that makes sense.
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