by Krishna Chugani, 11th Grade, Troy High School
It is astonishing that nearly 75 percent of novel, transmissible diseases inflicted upon humans were initially spread by animals. According to “Explainer: Animals’ Role in Human Diseases,” by Commonlit, these zoonotic illnesses, sparked by the spread of malignant germs that transmit from animals to people, are exceedingly common. It further explains that “The germs and other infectious agents that cause these diseases are known as pathogens. Most are microbes such as viruses or bacteria; others include fungi - even tiny worms and ticks.” Unfortunately, they cause zoonotic illnesses that are very common and harmful, and as reported by the Centers for Disease Control and Protection, “Scientists estimate that more than 6 out of every 10 known infectious diseases in people can be spread from animals.” Unfortunately, these infections can be exceptionally fatal. According to Jeanna Bryner, chief editor of Livescience, “13 of these zoonoses have killed 2.2 million people annually” (2012). Throughout history, there have been many zoonotic pandemics that have devastated the lives of millions. One occurence of a zoonotic outbreak was the Black Plague, which arose from bacteria carried by rats and fleas and eventually eliminated one-third of the European population during the mid 14th century. With the prevalence of excessive travel in today’s world, such diseases can spread more rapidly. For example, COVID-19 has brought the death toll to nearly 1.5 million to date. Clearly, animals have an immense impact on the spread of human diseases throughout our civilization.
Viruses are non-living microscopic parasites that depend on living hosts to reproduce and survive. “How Viruses Mutate” by the Canadian Broadcasting Corporation states that, “To survive: unlike plants, animals, and other organisms, the only way a virus can reproduce is through a host cell, which it does by attaching its surface proteins into the cell membrane and injecting its genetic material into the cell” (2009). Typically, when the immune system recognizes an antigen in the body, it will utilize its antibodies to combat it. Therefore, to survive an attack, the virus will mutate itself to become unrecognizable by the hosts’ immune system. Eventually, these toxic pathogens may spread to humans when they engage in this process of rapid change and evolution. The mutation of zoonotic viruses enables animals to become insidious transmitters of horrifying illnesses. Since humans have never encountered some novel zoonotic bacteria before, their immune system is unable to combat these pathogens. Furthermore, viruses also mutate into different strains to further expand while evading recognition by the host's antibodies. During this elusive process of multiplication, “new combinations can result”, the CBC states. These new strains make zoonotic illnesses even more difficult to contain. Therefore, the affected beings who had never encountered the disease previously have no immunity to combat it. This allows the pathogens to harm other organisms, which further increases the chance of humans being infected. Although some animals are germ reservoirs that are immune to the virulent disease, they could still spread the infectious disease to other, unprotected organisms through both direct or indirect contact.
There are multiple factors that make animals transmit pernicious diseases easily, allowing them to become widespread. Animals are constantly roaming in unsanitary environments, such as oil, mud, wastes, sewage, and trash, which exposes them to many harmful pathogens and bacteria. If an animal carries germs over vast distances, they may transmit sickness across many regions. When a susceptible animal makes contact with another diseased organism’s urine, saliva, feces, or body, it will contract the disease also. Another factor that promotes the transmission of contagions is the diet of infected animals. When predators consume a diseased animal, they ingest the same pathogens inside the animal, causing them to contract the illness as well. In an example presented by Commonlit, bats in Southeastern Asia devoured mango trees planted by farmers, contaminating the pigpens under them with an illness they were immune to (Mascarelli 2013). This started a viral infection, initially infecting the pigs and then farm workers. One influence that makes people more vulnerable to zoonotic diseases is their excessive dependence on livestock for consumption. “The demand for meat products has rapidly grown over time”, as stated in “Meat and Dairy Production” by Our World in Data (2017). If a diseased animal were to be consumed by humans, its pathogens may prompt another massive outbreak of a zoonotic disease. In addition, if humans come in contact with this bacteria or virus, they are at equal risk of contracting the illness. Interestingly, humans are making more unnatural interactions with wild animals to increase their infection vulnerabilities. For example, the modern practices of deforestation, urbanization, and converting land for farming force animals out of their natural habitat and into “human territory”. This increases our dangerous exposure to infected animals, which can instigate an epidemic. Another unnatural and risky practice is the selling of exotic animals in places, such as wet markets. In these marketplaces, there is an abundance of bodily fluids and wastes of various wild animals, making it an ideal breeding ground for novel viruses to develop and mutate to adapt to human bodies. At such sites, countless animals are killed in the wild and immediately sold to the public for consumption. These animals have likely roamed in unsanitary environments, where they could have come in contact with harmful pathogens that may in turn be taken by humans. These factors allow animals to transmit injurious viruses to humans, making their role vital in the spread of disease.
The Black Death was a pernicious disease that devastated millions of lives in Europe during the 14th century. It killed over 50 million people, which was roughly 40 percent of Europe’s population, in a span of four years. This rampant death toll demonstrated the lethal force of vector borne zoonotic diseases. According to CommonLit, the Plague was first transmitted from fleas to rats along trade routes in Asia. Soon, the diseased rodents aboard ships returning to Europe from China infected the European merchants (Gushue 2018). It proliferated and killed millions of people in Europe due to the lack of medical technology during the 14th century. Also, during the time period of this outbreak, most of the people were peasants that lived in crowded, unsanitary conditions. In addition, the malnourished diets of the peasants during the late Middle Ages also made the majority vulnerable to infectious diseases. Collectively, these factors helped propagate the Black Plague even further. However, by 1851, European society made some vital changes that helped contain this contagious pandemic. For example, they implemented quarantine, a new yet effective method used to mitigate the spread of disease by separating people through isolation, as stated in an article by History (2010). The increased hygiene and sanitation amongst people in European communities also contributed to the halt of the pandemic’s spread. Finally, the outbreaks of Black Death temporarily ceased when the hosts carrying the condition eventually died out. Although there was another massive outbreak of the plague in Asia during the 19th century that killed over 12 million people in China and India, scientists were able to understand the conditions more and halted its spread faster than the prior outbreak. The greater preparedness of people in the medical field made way for a functional vaccine to be developed by the late 1800s. The Black Death demonstrated the virulent force of zoonoses, which provided helpful insights for epidemiologists for future pandemics.
The Coronavirus is a novel zoonosis that has frightening resemblances to the prior pandemics and infects thousands of people every day. The disease broke out in Wuhan, China during 2019, likely originating from bats and pangolins. As stated in “Coronavirus came from Bats or Possibly Pangolins Amid ‘Acceleration’ of New Zoonotic Infections,” by the Washington Post, “In late December, four patients turned up ill in a hospital in Wuhan. Each had pneumonia-like symptoms and fever, and they tested negative for known diseases. Chinese authorities were on the lookout for a mystery illness such as this one, because they had seen it 17 years ago, when SARS flared in Guangdong province.” (Achenbach 2020). Although the Coronavirus is similar to the SARS virus that may have originated from bats, it has not been encountered by humans in previous years. Therefore, the human body and the scientific community have been unable to respond to this novel, yet mutated zoonotic virus. This infectious disease is transmitted through pathogens that could infect people through direct or indirect contact. Nations have taken precaution by implementing quarantine and closing non-essential businesses in order to slow its spread. Although the shutdown of schools and businesses has been destructive and devastating to the society, the ongoing lockdown has been necessary in order to contain the virus and prevent future waves. Currently, the further outcomes that this pandemic will have on society is highly uncertain. However, businesses are finding alternative ways like teleworking and delivery services to continue their operations during this pandemic , while others are implementing social distancing in an attempt to stop the spread of Coronavirus. Many pharmaceuticals and biotechs are racing to create functional vaccines that prevents the widespread disease as governments, benefactors, such as Bill Gates, and donations have been able to help speed up the process. Until then, similar to the prior pandemics, many hospitals are running low on resources, such as life-saving ventilators. Therefore, desperate healthcare workers have resorted to ranking systems, in order to determine which people need treatment the most. Unlike the recommendations before, the system does not completely exclude those with old age or disabilities. Sill, many are continuing to die due to the lack of resources and personal protective equipment in the hospitals at the moment. Scientists and companies are actively researching, developing, and testing effective vaccinations in hopes of eliminating this virulent global contagion soon. The Coronavirus will hopefully increase awareness in order to prevent future zoonotic diseases from affecting society and the economy of countries.
Ultimately, the severity of zoonoses demonstrate that animals have a significant role in the spread of diseases among humans. While they initially transmit to other animals, zoonotic viruses eventually affect susceptible humans when they mutate. Examples of pandemics gravely ravaging the world include the Black Death and modern-day COVID. Through overcoming these severe pandemics, people have learned the importance of social distancing, quarantine, proper hygiene, and medical advancements to curtail their spread. The factors that have contributed to the spread of zoonoses include the vast existence of germs in wild livestock habitats along with human interference. If humans are to prevent and mitigate future pandemics, we must change our current behaviors and reduce harmful contacts with wild animals and livestock. Instead of hunting them for food and unrestrained trade, while decimating their natural habitats, we must implement safer practices to abate the proliferation of these infectious diseases. Due to the disastrous and extensive nature of animal materials in our contemporary times, the study of zoonotics is evermore vital and urgent. In order to prevent subsequent outbreaks, proper measures must be taken to reduce the rising rates of infection. Therefore, society must continue to test organisms for disease, increase epidemiological research, develop functional vaccines, and minimize our unnatural and dangerous contacts with wildlife. If countries around the world are to thrive, zoonoses must be prevented to avert future turmoils.
Works Cited
Achenbach, Joel. “Coronavirus Came from Bats or Possibly Pangolins amid 'Acceleration' of New Zoonotic Infections.” The Washington Post, WP Company, 10 Feb. 2020, www.washingtonpost.com/health/coronavirus-came-from-bats-or-possibly-pangolins-amid-acceleration-of-new-zoonotic-infections/2020/02/07/11eb7f3a-4379-11ea-b503-2b077c436617_story.html.
Bryner, Jeanna. “13 Animal-to-Human Diseases Kill 2.2 Million People Each Year.” LiveScience, Purch, 6 July 2012, www.livescience.com/21426-global-zoonoses-diseases-hotspots.html.
“FAQ: How Viruses Mutate | CBC News.” CBCnews, CBC/Radio Canada, 4 May 2009, www.cbc.ca/news/technology/faq-how-viruses-mutate-1.780051.
Gushue, Margaret. “The Black Death.” CommonLit, 2018, www.commonlit.org/es/texts/the-black-death.
Mascarelli, Amanda Leigh. “Explainer: Animals' Role in Human Disease.” CommonLit, 2013, www.commonlit.org/texts/explainer-animals-role-in-human-disease.
Ritchie, Hannah, and Max Roser. “Meat and Dairy Production.” Our World in Data, 25 Aug. 2017, ourworldindata.org/meat-production.
Roos, Dave. “Social Distancing and Quarantine Were Used in Medieval Times to Fight the Black Death.” History.com, A&E Television Networks, 25 Mar. 2020, www.history.com/news/quarantine-black-death-medieval.
“Zoonotic Diseases.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 14 July 2017, www.cdc.gov/onehealth/basics/zoonotic-diseases.html.