Posted on: March 20, 2020 at 7:30 pm

As the novel coronavirus, COVID-19, continues to spread throughout the globe, scientists and medical researchers have been working tirelessly to determine the source of the outbreak in order to better understand how its spread.


After extensive research, scientists have now concluded that the coronavirus that causes COVID-19 likely originated in bats, then somehow passed to another animal, such as a pangolin, before finally being transmitted to humans [1].

This transmission likely occurred in a live animal market, also called a “wet market”, in Wuhan, a city in China’s Hubei province. These markets, which provide ideal conditions for a virus to spread, are common in Asia, Africa, and Latin America [2].


As more cities and countries enact increasingly strict social isolation laws to quell the spread of the virus, scientists are warning that this outbreak is just the tip of the iceberg, and it is inevitable that pandemics such as this will be occurring with greater and greater frequency.

A number of researchers today are warning that human destruction of biodiversity is creating conditions for new viruses and diseases, such as COVID-19, that humans have never seen before, and this will have a catastrophic health and economic impact around the world.

Read: Why Are People Hoarding Toilet Paper? Psychologists Have An Answer

Animal Pathogens Infecting Humans

When harmful pathogens such as viruses, bacteria, parasites, and fungi, are passed from an animal to a human, they cause zoonotic diseases, or zoonoses. Often, these contagions do not affect the animal, but could be deadly in humans [3].


Public health experts believe that zoonotic diseases are the biggest threat to human health in terms of generating new pandemics, since more than six in ten known infectious diseases, and three-quarters of new or emerging diseases, are believed to be zoonotic [3].

These diseases can be highly unpredictable, since they will optimize for their current host, before being passed into humans. That makes them difficult to track, because it is nearly impossible to know whether a virus in chickens, for example, will jump to humans or not [4].

Over the past two or three decades, a number of zoonotic viruses have matured to a dangerous point.

Previous Zoonotic Outbreaks

In the last century, the world has seen several deadly outbreaks of viruses that originated in animals, perhaps the most notable being the 1918 influenza pandemic that killed an estimated fifty million people in only a few months. 

H1N1 influenza, which originated in birds, infected more than one-third of the world’s population, and unlike many other outbreaks, hit young adults the hardest [5].

Another strain of H1N1 cropped up again nearly a century later in 2009, this time originating from pigs [5].

The Ebola virus, first identified in 1976, has caused outbreaks predominantly in Africa in the 1980s and 1990s and can kill up to ninety percent of its victims. Scientists believe that the disease may have infected humans via chimpanzees, but can then be passed from person to person through direct contact with bodily fluids of an infected person [6,7].

Other zoonotic diseases include the SARS outbreak in 2002, which was thought to have originated in bats, and the MERS pandemic that swept the middle east in 2012, which came from an animal of unknown origin [8,9].

Read: How to Distinguish between the Coronavirus and Flu

Human Activity Causing New Viruses

For years, experts thought that areas with high levels of biodiversity, such as tropical forests, were a major threat to human health because their vast numbers of exotic wildlife carried viruses and pathogens that could infect humans.

Recently, however, scientists have determined that it is not these environments themselves that are the threat, but rather humanity’s destruction of them, and subsequently their biodiversity, that is the problem [10].

Human activity, such as building roads, mining, hunting, and logging, is incredibly disruptive to these ecosystems and is likely the reason behind the recent increase in zoonotic diseases.

“We invade tropical forests and other wild landscapes, which harbour so many species of animals and plants – and within those creatures, so many unknown viruses,” says David Quammen, author of Spillover: Animal Infections and the Next Pandemic. “We disrupt ecosystems, and we shake viruses loose from their natural hosts. When that happens, they need a new host. Often, we are it.” [10]

In a 2008 report, Kate Jones, chair of ecology and biodiversity at UCL, identified 335 new diseases from 1960 to 2004 and found that sixty percent of them came from animals [11].

Jones explained that these diseases are being increasingly linked to environmental change and human behavior, and rapid urbanization and population growth are bringing people into closer contact with wild animals.

“We are going into largely undisturbed places and being exposed more and more,” she said. “We are creating habitats where viruses are transmitted more easily, and then we are surprised that we have new ones.” [10]

Eric Fevre, chair of veterinary infectious diseases at the University of Liverpool’s Institute of Infection and Global Health, explains that the risk for humans being infected by these zoonotic diseases is higher now than ever before because they are now just as likely to appear in urban environments as remote jungles.

“We have created densely packed populations where alongside us are bats and rodents and birds, pets and other living things. That creates intense interaction and opportunities for things to move from species to species,” he says [10].

As humans continue to reduce or completely destroy the natural barriers between populations and host animals, we will continue to create ideal conditions in which disease can spread. It is not the natural ecosystems that are the source of the threat, it is human activities that do the real damage.

Read: 20 Coronavirus Myths Busted

Are Markets to Blame?

Since the outbreak of COVID-19, “wet markets” that sell live animals and fresh produce, such as the market in Wuhan thought to be the epicenter of the disease, have been shut down, and Beijing has now outlawed the trading and eating of wild animals, with the exception of fish and seafood [12].

Markets like this exist all over the world, selling live wolf pups, salamanders, crocodiles, scorpions, rats, squirrels, foxes, civets, and turtles, as well as monkeys, bats, rats, and dozens of species of birds, mammals, insects and rodents [10].

Some experts, however, believe that outlawing markets like these is not the answer to the problem. This opinion is held by Delia Grace, a senior epidemiologist, and veterinarian with the International Livestock Research Institute, which is based in Nairobi, Kenya. 

“These markets are essential sources of food for hundreds of millions of poor people, and getting rid of them is impossible,” she says [10].

Wet markets are often considered part of the informal food trade, but the link between them and the spread of disease isn’t always so clear-cut.  

A study in 2019 argued that the increasing global health challenge that zoonoses create is deeply connected with the urbanization of poverty and inequalities within cities, and to tackle this problem there needs to be more emphasis placed on living conditions, the wider socio-environmental conditions of urban areas, and the structure of our cities [13].

What Can We Do About This?

“We must think about global biosecurity, find the weak points and bolster the provision of health care in developing countries. Otherwise we can expect more of the same,” argues Jones [10].

Brian Bird, a research virologist at the University of California, Davis School of Veterinary Medicine One Health Institute, describes our current day and age as being in a “constant state of emergency”.

“Diseases are more likely to travel further and faster than before, which means we must be faster in our responses. It needs investments, change in human behaviour, and it means we must listen to people at community levels,” he says [10].

Other experts argue that we need to rethink urban infrastructure, particularly in lower-income areas. While the short-term response to a viral outbreak is to contain the disease, a more long-term approach requires a change in the way we approach urban planning and development to make it more difficult for infectious diseases to spread so rapidly through cities [10].

Bird has no doubt that another pandemic will happen, and if there is anything that we have learned from the recent COVID-19 outbreak, it is the importance of being prepared. 

“We can’t predict where the next pandemic will come from, so we need mitigation plans to take into account the worst possible scenarios” [10].

Keep Reading: Opinion: Are You Young and unafraid of the coronavirus? Great, Now stop killing people

Brittany Hambleton
Team Writer
Brittany is a freelance writer and editor with a Bachelor of Science in Foods and Nutrition and a writer’s certificate from the University of Western Ontario. She enjoyed a stint as a personal trainer and is an avid runner. Brittany loves to combine running and traveling, and has run numerous races across North America and Europe. She also loves chocolate more than anything else… the darker, the better!

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