How to Cause More Pandemics!

Published by on March 25, 2021

Discussions surrounding the future of pandemics are understandably uncomfortable as many countries have yet to leave behind the current COVID-19 pandemic. Alas, it takes a couple Google searches to learn that many experts have agreed that the next global pandemic is not a matter of if, but when. In 2007, the World Health Organization warned that the rate of infectious diseases emerging reached a historical high which in addition to natural phenomena was attributed to various human actions (World Health Organization, 2007). 

As you are aware, the SARS-CoV-2 virus was traced to have likely origins from bats and was amplified in a Wuhan wet market (Ye et al., 2020; Mackenzie and Smith, 2020). In fact, over half of known and emerging infectious diseases are zoonotic (Salyer et al., 2017; Morse et al., 2012). Some of the recent notorious ones are listed in Table 1.

Table 1: A selective handful of some recent outbreaks of zoonotic diseases. All the pathogens here are RNA viruses. The zoonotic transfers listed here are the most likely and most generally accepted. Details about their evidence and level of agreement warrant their own research and is beyond the scope of this table.

Zoonotic diseases describe infectious pathogens, commonly viruses and bacteria, that have jumped from animals to humans (Lederberg, 2002). Let’s first dissect what enables the spread of viruses. Viruses need hosts to survive. When the host dies so does the virus, and so their spread is directly enabled by the proximity of available hosts. Additionally, every time a virus replicates it gains random mutations (Carrasco-Hernandez et al., 2017). While many mutations are insignificant, some are able to grant the virus new abilities including the ability of inter-species infection. There are five stages of pathogen emergence from animal to humans outlined in Figure 1.

Figure 1: The five stages of pathogen emergence from animals to humans with four examples of pathogens in stages 2 to 5 (Wolfe, Dunavan and Diamond, 2007)

With more interactions between and within humans and animals, viruses have more opportunities to mutate and become outbreak-causing zoonoses (Peck and Lauring, 2018). The high evolutionary rates of RNA viruses in particular are attributed to high mutation rates (Peck and Lauring, 2018). Figure 2 provides an elementary view of the flow of pathogens between wildlife, livestock, and humans.

Figure 2: Flow of pathogens in the wildlife–livestock–human interface. Peri-domestic wildlife include wildlife that lives around humans such as rats (Jones et al., 2013)

Of the many types of wildlife–livestock–human interfaces industrial and backyard livestock farming has the highest connectivity between the wildlife, livestock, and human populations (Jones et al., 2013). The high concentration of genetically identical animals accelerates the evolution and spread of viruses. This is a widespread issue as it’s estimated that globally intensive livestock farming takes up 26% of ice-free land (Food and Agriculture Organization of the United Nations, 2012) and houses 90% of livestock (Anthis and Anthis, 2019). Additionally, the shipping of livestock around the world can also render animals as long-distance vectors which further increases chances of outbreak around the world. 

Zoonotic viruses aren’t the only pathogen whose damage to human health is amplified due to factory farming. One of the most concerning threats to our healthcare, antimicrobial resistance (AMR), is worsened as well. AMR arises when bacteria, like viruses, evolve mechanisms to evade antibiotics and in the future can render many common maladies such as UTIs and STDs as fatal (Habboush and Guzman, 2021). An unpopular fact is that the majority of antibiotics in the world are used on livestock which is concerning as AMR is largely credited to the overuse of antibiotics (Ventola, 2015). Some of the antibiotics are used to treat common diseases arising from factory conditions while others have non-therapeutic uses such as to induce excess weight gain with minimal feed (Landers et al., 2012). 

As bacteria can survive on their own, the potential pathways resistance bacteria can take to reach humans is numerous (Figure 3).

Figure 3: Figure depicting potential pathways resistant bacteria can use to transfer between livestock, the environment, and ultimately reach humans (Health Canada, 2002)

With more research, it is becoming increasingly apparent that intensive livestock farming is linked with the future of human health. While managing human-to-human contact is of great importance, we need more proactive approaches that accept the agricultural nexus as a key player. Effectively battling the accelerated evolution of zoonoses and AMR will have to first come with an evolution of our perspective and the global food system.

Works Cited

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