Zoonotic Diseases and Human Behavior

Zoonotic Diseases and Human Behavior

Most of you know that COVID-19 is an infectious disease that can cause mild to severe respiratory illnesses. But not many of you may know exactly where it comes from.

In the beginning of the coronavirus outbreak, there were conspiracy theories that a Chinese individual who consumed bat soup had started the spread. This is far from the more complex truth! The dictionary definition states that coronaviruses are a group of related viruses that cause diseases in mammals and birds. They are collectively known as “zoonotic” diseases, meaning that a disease is transmitted between species, from animals to humans or vice versa. COVID-19 is not the first case of a zoonotic disease plaguing our world, and it may not be the last. 

person in white medical scrub suit standing beside white and blue hospital bed

Scientists have been researching the genetic material and the evolutionary history of the coronavirus, along with the ecology of bats. They have found that the genome of COVID-19 is similar to that of other bat coronaviruses, as well as those of pangolins. So, although it is not clear how exactly it had spread, it is clear that COVID-19 originated in bats. Bats host 1.8 zoonotic viruses on average because they live very close to each other, giving plenty of opportunities for pathogens to spread between bats. These viruses are not deadly to bats as they have evolved their sophisticated defense mechanisms over time to protect themselves. Owing to the increased contact between humans and bats (or through an intermediate animal host), the virus is likely to have jumped from the bats to the humans. 

Humans and bats have a lot of contact, especially as we continue to venture into their habitats. Through hunting, selling, and trading, we are coming into contact with these animals like never before. The Seafood Market in Wuhan (where many of the early cases originated), did sell and trade live animals, including bats. So long as human beings continue to disrupt and destroy animal habitats, zoonotic diseases are likely to be common. UN experts had warned that these diseases will keep increasing unless proper action is taken to protect wildlife and preserve the environment. In fact, it seems that human beings need to heed the warnings of past experiences and adjust several aspects of their lives. 

brown and black bird on tree branch during daytime

COVID-19 is not the first case of zoonotic diseases in human history. Other examples include the Bubonic Plague, MERS, Ebola, and the West Nile Virus. The Bubonic Plague, or the Black Death, lasted from 1346-1353 (although some cases have re-emerged recently). It was introduced to Europe in October 1347, when 12 ships from the Black Sea arrived at the Sicilian port of Messina, Italy. Many of the sailors on board were already dead, and those who survived had spread the disease throughout Europe. After it afflicted Messina, the plague spread to France and North Africa.

Scientists learned that the disease is transmitted from rodents to humans through the bite of infected fleas. These pests thrived aboard the trading ships, where hygiene and sanitation methods were lacking. Over 25 million people died in the 14th century. The Black Death epidemic had run its course by the early 1350s, but it still continues to reappear. Although there are antibiotics available to treat it, the WHO had warned that there are still 1,000 to 3,000 cases every year. Aside from the discovery of the antibiotic, the plague was controlled by the implementation of proper sanitation methods and public health practices. In the past, sailors on board trading ships had little means of maintaining cleanliness, which allowed for the mass spread of this disease. The most recent re-emergence of the Bubonic Plague occurred in western Mongolia in mid August, 2020. He had bought two dead marmots before he fell ill and died. These cases prompted Russia’s nearby Burytia region to test rodents for the bubonic plague and urge residents not to hunt or eat marmots. 

Another more recent outbreak of a zoonotic disease that you may be familiar with is Ebola. Ebola was introduced to the human population through the eating or handling of certain infected mammals such as monkeys and bats. It is then spread from human to human through contact with the bodily fluids of the infected person. Ebola first originated in 1976 in the Democratic Republic of Congo, and then spread to multiple African countries. Between 2014-2016, 28,000 people died in Guinea, Liberia, and Sierra Leone. Many of these African countries are impoverished and lack healthcare facilities. Developing countries like these always face the brunt of zoonotic diseases, or any disease for that matter. Ebola was able to be controlled through the assistance of WHO vaccination campaigns. No new cases have been reported since 2016. 

woman holding test tubes

These are only some examples of zoonotic diseases that have plagued the world in human history. It is no secret that such diseases can cause huge economic and social disruption. The UN Environment Program (UNEP) estimated that over the last two decades and before COVID-19, zoonotic diseases caused economic damage of $100 billion. 

You may be wondering – how do we avoid such instances? It seems that it starts with a change in human behavior. We must start by paying attention to protecting wildlife, reducing our demand for animal protein and maintaining hygiene and cleanliness. According to a report by the UNEP and the International Livestock Research Institute, the disease transmission from animals to humans is facilitated by the exploitation of our natural environment. Through land degradation, wildlife exploitation, resource extraction and climate change, the way animals and humans interact significantly changes. By destroying animal habitat, wild animals are forced to enter into cities, increasing their chances of interacting with human beings. Urban spaces have plenty of food for wildlife species, making cities a melting pot for evolving diseases. Additionally, by venturing into forests to hunt animals for the purpose of trading and selling, we increase our contact with wild animals as well. 

Inger Anderson, under-secretary general and executive director of the United Nations Environment Program, warned that, “If we keep exploiting wildlife and destroying our ecosystems, then we can expect to see a steady stream of these diseases jumping from animals to humans in the years ahead.” We must be deliberate about protecting our natural environment. 

black rhinoceros on green grass field during daytime

In terms of our demand for animal protein, meat production has increased by 260% in the last 50 years. Governments and local municipalities should keep track of which animals are newly arriving in cities, and whether people are engaging in wildlife trading in market places or not. Seeing as initial cases of COVID-19 may have spread from the selling of wild animals in the Wuhan marketplace, such instances must be closely monitored moving forward. In places where it is illegal to buy and sell such wild animals, we should follow these rules. 

Lastly, it is important for us to maintain proper sanitation methods, both at a micro and at a macro level. This lesson can be learned after analysing what led to the Bubonic Plague, where rats thrived in cramped and dirty trading ships. We must pressure our governments to continue funding healthcare and sanitation infrastructure. This also includes waste disposal, as several species of bacteria can thrive in dirty areas. 

Unfortunately, it is difficult to implement such changes in human behavior. We love our meat, we love our cars and factories. But we must be more careful and intentional moving forward, if we want to prevent the widespread economic and social damage caused by zoonotic diseases such as the coronavirus. 

Priyasha Chakravarti

Priyasha is a 17 year old senior studying the IBDP in International School Manila in the Philippines. She is originally from India. Her favorite subjects are Politics, Economics, Environmental Science and English. She is very passionate about addressing social justice issues, political polarisation, and youth involvement in political and global issues. She is a writer for a environmental youth led organisation called Bye Bye Plastic Bags Philippines and the co-head of research and content for Project Puno. In addition, she is a writer for a youth led news publication called Genzenith. Priyasha is also a co-founder of a service and literary initiative called Inside Out, where she combines her love of literature and service to create a positive change. Aside from working for her organisations and stressing over IB/college apps, her hobbies include playing badminton, singing, and Model United Nations. She is very excited to be a writer, poet, and editor for Zenerations! (edited) 


“Coronavirus: Fear over Rise in Animal-to-Human Diseases.” BBC News, BBC, 6 July 2020, www.bbc.com/news/health-53314432.

“Ebola Virus Disease.” World Health Organization, World Health Organization, 10 Feb. 2020, www.who.int/news-room/fact-sheets/detail/ebola-virus-disease.

Ellis, Emma Grey. “The Coronavirus Outbreak Is a Petri Dish for Conspiracy Theories.” Wired, Conde Nast, 4 Feb. 2020, www.wired.com/story/coronavirus-conspiracy-theories/.

Gan, Nectar, and Jessie Yeung. “China Seals off Village after Bubonic Plague Death in Inner Mongolia.” CNN, Cable News Network, 7 Aug. 2020, edition.cnn.com/2020/08/07/asia/china-mongolia-bubonic-plague-death-intl-hnk-scli-scn/index.html.

History.com Editors. “Black Death.” History.com, A&E Television Networks, 17 Sept. 2010, http://www.history.com/topics/middle-ages/black-death.

Huang, Pien. “Bats Carry Many Viruses. So Why Don’t They Get Sick?” NPR, NPR, 9 Feb.2020,www.npr.org/sections/goatsandsoda/2020/02/09/803543244/bats-carry-many-viruses-so-why-dont-they-get-sick.

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