As uncertainty looms and we find ourselves navigating uncharted territory with the emergence of COVID-19, many of us are wondering: How did we get here? Where did this virus come from? Did humans cause this? Where did we go wrong?
In part 2 of our deep-dive series, we have put together an article summarising some of the latest research on climate change, human behaviour and COVID-19. We hope to help shed some light on the situation for you...
Let’s jump straight in. Many researchers today believe humanity’s destruction of biodiversity has created the perfect conditions for new viruses and diseases such as COVID-19. But, habitat and biodiversity loss increase globally, is the COVID-19 outbreak just the beginning?
Well, this has happened before...
In January 1996, Ebola, a deadly virus that humans were not familiar with, spilled out of the forest of village Mayibout 2 (population: 150), which sits deep in the great Minkebe Forest in northern Gabon. It killed 21 of 37 villagers who were reported to have been infected, including a number who had carried, skinned, chopped, or eaten a chimpanzee from the nearby forest. This village was no stranger to disease, among them; including malaria, dengue, yellow fever and sleeping sickness. However, they lived in fear that Ebola would return.
John Vidal, environment editor of The Guardian traveled to this village in 2004 to investigate why new deadly diseases were emerging from biodiversity “hotspots”, i.e tropical rainforests and bushmeat markets in African and Asian cities. He recalls the villagers explaining the story of the outbreak- how children had ventured into the forest with dogs that had killed the chimp. Everyone who cooked or ate it developed a terrible fever within a few hours, with some dying immediately, and others taken to a hospital. The villagers grew weary of the forest, no longer trusting a place that had served them so well in the past.
Around this time, it was still believed that tropical forests and additional intact natural environments that thrived with exotic wildlife were a threat to the health of human society as they harboured viruses and pathogens that led to new diseases in humans such as Ebola, HIV, and dengue fever.
However, today, more research is emerging that demonstrates that it is our fault that these diseases spread. As we invade and destroy biodiversity and natural ecosystems, we create harmful and ‘unnatural’ links between humans and other living beings.
So, was it human activity, such as road building, mining, hunting and logging, that triggered those Ebola epidemics in Mayibout 2 and elsewhere in the world? Is that ultimately a similar reason for the emergence of COVID-19 today?
Yes. Yes, unfortunately, it was. By exploiting the environment, we have ultimately created our own worst enemy. David Quammen, author of Spillover: Animal Infections and the Next Pandemic, said it best, “We cut the trees; we kill the animals or cage them and send them to markets. We disrupt ecosystems, and we shake viruses loose from their natural hosts. When that happens, they need a new host. Often, we are it.”
The US Centre for Disease Control and Prevention (CDC) estimates that three-quarters of new or emerging diseases such as Ebola, SARS, bird flu, and now COVID-19, originate in animals. Pathogens easily jump across from animals to humans, and proceed to spread rapidly to new environments.
Animals have played a large role in the spread of disease for centuries; two examples of these being rabies - from bats, raccoons, skunks and foxes, and the bubonic plague - from rats. Other diseases that have crossed over to humans include Lassa fever, which originated in 1969 in Nigeria, Nipah from Malaysia, and Sars from China, which killed more than 700 people in 2003. The illness spread to more than two dozen countries in North America, South America, Europe, and Asia before it was contained. Zika and West Nile virus, which emerged in Africa, have mutated, and become established on other continents. Mers, linked to camels, originated in the Middle East and spread rapidly.
Viruses & diseases that jump from animals to humans are termed ‘zoonotic’ diseases, and it seems like history is repeating itself with COVID-19, which emerged last year in Wuhan, China, linked to wet-markets, where humans are in close contact with a wide variety of live & butchered-on-site animals from around the world.
"Poorly regulated, live-animal markets mixed with illegal wildlife trade offer a unique opportunity for viruses to spill over from wildlife hosts into the human population," said the Wildlife Conservation Society in a recent statement.
Thomas Gillespie, disease ecologist and associate professor in Emory’s University department of environmental sciences, says something extremely important that we should all remember, “Pathogens do not respect species boundaries.” He has been studying how shrinking natural habitats and changing behaviour add to the risk of diseases spilling over from animals to humans, claiming that he isn’t “surprised about the coronavirus outbreak.” He goes on to say that “the majority of pathogens are still to be discovered. We are at the very tip of the iceberg.”
He explains that humans have made it easier for diseases to spread, accelerating the process by reducing the natural barriers between host animals, in which the virus originated, and themselves. Wildlife is under stress, due to the fact that habitats have been destroyed by major landscape changes implemented by humans. This leads to overcrowding of species that come into greater contact with humans. Species that wouldn’t normally come into contact with each other are mixing together and with humans. We have created unnatural conditions by messing with the laws of nature.
It seems that human health research has underestimated our surrounding natural ecosystems and how human interaction and invasion into them may facilitate the development of these viruses. Richard Ostfeld, distinguished senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York, says that “There’s misapprehension among scientists and the public that natural ecosystems are the source of threats to ourselves. It’s a mistake. Nature poses threats, it is true, but it’s human activities that do the real damage. The health risks in a natural environment can be made much worse when we interfere with it.”
The more that humans disturb forests and habitats, the higher the likelihood that zoonotic diseases can cross from animals to humans.
As many of us know, COVID-19 was believed to have originated in a ‘wet market’, one that sells fresh produce and meat in Wuhan, China. This particular market processes numerous wild animals, including live wolves, salamanders, crocodiles, scorpions, rats, squirrels, foxes, koalas, civets and turtles; species that often would not meet in the wild, but are crowded together in unhygienic conditions, in close quarters with humans. This is the ideal place for a spillover event to occur and the transmission of a virus to take place. The first cases of COVID-19 were seen in stall-holders.
There have been waves of improvements made by the Chinese government in the regulation of such markets since the outbreak of the virus. You can view a collection of photographs that will give you a clearer picture of how it all started here (warning - it's not pretty). It’s not known how long regulations banning in-market slaughter will remain in-place.
Some scientists don’t believe that bans on live animals sold in urban areas or informal markets are necessarily the answer. An argument can be made that if these markets are banned, they will simply move underground, with even less hygienic conditions. Delia Grace, a senior epidemiologist and veterinarian with the International Livestock Research, based in Nairobi, Kenya, insists that “these markets are essential sources of food for hundreds of millions of poor people, and getting rid of them is impossible.” Where people may not be familiar with an informal street market in the Western world, this is the cultural norm for many cultures in Africa and Asia, where the trade in wild animals is rampant.
Perhaps we need to look at the trade of wild animals in general, rather than solely focusing on these informal markets? While a link can be established between informal markets and diseases spreading to humans, COVID-19 being one of them, evidence from an issue paper in the latest edition of the Environment and Urbanization journal, shows the link between informal markets and disease is not always so clearcut...
Eric Fèvre, Professor of veterinary infectious diseases at the University of Liverpool and Cecilia Tacoli, Principal Researcher in IIED's Human Settlements research group, have come to the conclusion that these informal, or wet, markets are a staple of nutrition in urban and rural communities in Africa and Asia. For this reason, China has made sure to invest in upgrading many of its cities’ traditional food markets rather than simply banning them.
When we get to the bottom of it, the main issue is with the sale of wildlife, for it is wild animals rather than farmed animals that are the natural hosts of many viruses (partly due to the rampant use of antibiotics in factory farms, causing a whole host of other problems). In response to COVID-19, China has placed a “comprehensive” ban on the trade and consumption of wild animals, but a troubling one with loopholes for trade in wild animals for medicinal uses. According to an analysis by the Wildlife Conservation Society, the decision does not ban trade for fur, medicine, or research, which creates a potential loophole for traffickers. It won’t be easy to put a stop to the sale and consumption of these wild animals, as the cultural roots for China’s use of wild animals run deep, and it’s not just for food, but traditional medicine, clothing, ornaments, and sometimes pets.
This isn’t the first time officials have tried to contain the trade of wildlife in Asia. After SARS in 2003, civets (mongoose-type creatures), were banned when it was discovered they likely transferred the virus to humans. The selling of snakes was also briefly banned in Guangzhou after the SARS outbreak. But today, dishes with these animals are still eaten in parts of China.
Part of the pushback against the banning of the sale of this wildlife is how lucrative of a business it is. A government-sponsored report in 2017 by the Chinese Academy of Engineering found the country's wildlife trade was worth more than $73 billion and employed more than one million people.
So, that's the wildlife trade & COVID-19. But what about climate change? Is this making the problem worse?
As for the effects of climate change on the emergence of new viruses, Katharine Anne Scott Hayhoe, an atmospheric scientist and professor of political science at Texas Tech University, where she is director of the Climate Science Centre, explains the correlation succinctly...
Some diseases, such as Zika, are spread by animals like mosquitoes and ticks, and can be expected to increase in prevalence as a warming world expands the animals’ geographic range as the climate warms. This means that certain vector-borne diseases, such as malaria, dengue fever or Lyme disease, may move into new territories in the future, as the carrying insects, such as mosquitoes, bring disease-carrying pathogens from other hosts. Climate change is increasing the number and range of such insects, and bringing them into more contact with humans.
Another connection between climate change and disease, is air pollution. Air-borne polluting particles have been found to exacerbate the effects of the disease, making people more susceptible to respiratory illnesses. A look at the SARS epidemic in China in the past found that patients from regions with high air pollution were “twice as likely to die from SARS” compared to patients from regions with cleaner air.
Epidemiologists have documented the volume of coronaviruses in the animal world and warned of the threat they pose. “There is a database that shows there are some 30,000-odd isolated coronaviruses in animals, says Seth Berkley, a epidemiologist who heads GAVI, the global vaccination initiative. COVID-19 is just one example of a coronavirus, and it’s already mutating into multiple strains.
Epidemiologists have proposed studying those 30,000 viruses to see which might fit the receptors on human cells... “But the problem is, people don’t invest in those types of research,” Berkley said. “And of course I think—given it’s an evolutionary certainty that we’re going to see this—that we should be.” said Seth Berkley.
The demand for wood, minerals, and resources from the global north has led to degraded landscapes and habitat destruction, which has pushed humankind further and further into the danger zone of exposure to zoonotic viruses. Hunters, loggers, market traders, and consumers are only just beginning to understand the risk.
I hope you’ve stuck with us throughout this article, we know it’s a lot of information. We thought it would be important to help articulate the relationship between the climate, environment, and viruses, especially going forward in the future. As you can, see, it’s a complex issue.
COVID-19 has changed everything, and it continues to spread rapidly across the world today. Collectively, governments will need to re-evaluate pandemic response plans, budgets, and healthcare systems. Scientists will race against the clock to develop a vaccine and hopefully, people will begin to understand far-reaching effects our behaviour can have on the planet.
Mess with nature, she’ll fight back. Covid-19 is a live case-study. We hope this sparks the beginning of a world awakened to how vulnerable we are as humans.