Covid-19 has changed the world, mostly for the worse. The pandemic has resulted in hundreds and thousands of deaths, millions of infections, global lockdowns resulting in a recession whose effects we are yet to see or even comprehend, millions losing their jobs and incomes, and with no vaccine yet, a bleak and uncertain future.

What this novel coronavirus has also revealed is the increasing precariousness of our relations with the environment and thereby with wildlife, drastically increasing our exposure to viruses of all types, novel and otherwise. It has also driven home the sobering point that unless there are concerted efforts to halt our encroachment of wildlife habitats and protect biodiversity, more pandemics are likely in the future. And at a time when humanity is rapidly running out of time to beat the climate change ticking clock and combat growing income and social inequalities, it simply cannot afford another pandemic. If there’s a sliver of silver lining to this disastrous series of events, it could be that people may finally start realising the catastrophic and cascading consequences of their ‘benign’ actions that are actually rooted in the exploitation of nature and end up harming each one of us.

What are zoonotic diseases?

According to the CDC website, more than 6 out of 10 known infectious diseases in people can be spread from animals, and 3 out of 4 new or emerging infectious diseases in people originate in animals.

Zoonotic diseases (diseases spread by animals who carry the harmful germs) spread when germs are transmitted between animals and people. This is how:

  • Direct contact: Coming into contact with the saliva, blood, urine, faeces, or other body fluids of an infected animal or through petting, handling, getting scratched
  • Indirect contact: Coming into contact with areas where animals live and roam, or objects or surfaces that have been in contact with infected animals, such as aquarium tank, pet habitats, chicken coops, barns, food dishes, etc.
  • Vector-borne: Through insects that act as vectors for the disease-causing agent. For instance, being bitten by a tick or an insect 
  • Foodborne: Eating or drinking contaminated food or water, such as unpasteurised milk, undercooked meat, or raw, unwashed fruits and vegetables that are contaminated with faeces from an infected animal
  • Waterborne: Drinking or coming in contact with water that has been contaminated with faeces from an infected animal

A paper by Roger Frutos and his colleagues in Frontiers in Medicine lays out the three conditions that leads to the emergence of an infectious disease: the pathogen causing the outbreak must be compatible with humans, while the other two conditions are anthropogenic – there must be contact between humans and the pathogen carrier and a human-to-human urban cycle must be possible. Covid-19 fulfils all three conditions.

Most of the important human pathogens are either zoonotic or originated as such before adapting to human beings, and more than three-quarters of emerging infectious diseases are directly transmitted. A review conducted by the Secretariat for the Convention on Biological Diversity and WHO found that one of the major risks driven by biodiversity loss is infectious diseases transmitted from wildlife to humans.

While the exact origin of Covid-19 is still murky, what we do know is that it is zoonotic. The most popular hypothesis is that it spread into humans from an intermediate host that carried the virus from bats and then (most likely) to a wholesale market in Wuhan, China. WHO suggests that this market was the source of the outbreak or played a role in amplifying it. From there, the rest is history and our unfortunate present. Other deadly coronaviruses spread in a similar way – civets were intermediaries for the spread of the severe acute respiratory syndrome (SARS) that originated in bats. For Middle East respiratory syndrome (MERS), also a coronavirus disease, it was camels that infected humans and other animals around them.

Biodiversity affects us and We affect it

What is the relation between infectious disease and wildlife? 

The concept of planetary health is useful to grasp the interconnectedness of human activity, biodiversity, and climate change. As stated in this paper published in The Lancet, ‘planetary health is based on the understanding that human health and human civilisation depend on flourishing natural systems and the wise stewardship of those natural systems.’ However, the Anthropocene Age is increasingly marked by rampant exploitation of Earth’s natural resources with scant regard for the environment, biodiversity, or even people themselves. This has enormous and often ominous implications for every living being on this planet, including health effects. Disease outbreaks, like the one the world is going through right now, will become increasingly more common with rapid environmental degradation. 

A 2006 WHO report estimated that about a quarter of the global disease burden and more than a third of the burden in children was due to modifiable environmental factors. Other reports by reputed organisations such as IPCC have repeatedly stressed on the fact that changes in the global environment will have adverse impact on human health. As The Lancet report points out, zoonotic disease outbreaks were predicted by several studies which reported an increased risk of such disease transmission in disturbed and degraded habitats. In other words, when biodiversity doesn’t thrive, diseases survive.

As this paper in Nature states, biodiversity changes increase the risk of infectious disease exposure in plants and animals because infectious diseases, by definition, involve interactions among species. Deforestation, land-cover change, changes in the local ecosystems, and resource depletion mean that animals are forced to adapt. For example, fruit bats are the likely host of the Ebola virus. They are social animals that often congregate in large groups. Anthropogenic activities impact their migratory patterns, group size, and resource availability, leading to unnatural and unpredictable changes in their behaviour. Often this can bring about increased animal-to-human contact, leading to novel diseases and global crises.

Bats naturally host many viruses but in the wild this isn’t a problem as species tend to specialise within distinct patterns, and interactions with other species is well-established and contained. But with changes in land use, such viruses are more likely to be transferred by them to humans or animals if they live in ecosystems that have been disturbed by human activities, such as recently cleared forests or swamps drained for farmland. Many studies show that the density and variety of bat-borne viruses is higher near human habitation.

The same Nature paper found that between 1940 and 2005, almost half of the global zoonotic infectious diseases in humans were driven by changes in land use, agricultural and other food production practices, or through wildlife hunting. This means that the emergence of such diseases is due to increased contact rates between humans and other animals. The highest-risk areas are where human population growth is high, the ecology is disrupted due to human developments, and human and wildlife populations overlap substantially.

Biodiversity can serve as protection against transmission and help reduce exposure to infectious agents. However, with the rapid degradation of ecosystems exacerbated by climate change, the number of invasive species is slated to increase, causing significant impacts on human health including ‘diseases or infections, exposing humans to bites and stings, causing allergic reactions, and facilitating the spread of pathogens.’ Environmental changes have meant that such diseases emerge and re-emerge at higher rates.

Climate change has made such pandemics a matter of when and not if. The rapid warming of the planet and shifting climate zones are causing wildlife to migrate to new places including those where humans reside in significant numbers, putting them in close contact with species they haven’t previously encountered and breeding new forms of diseases. Then there’s the rampant air pollution that increases our vulnerability to such diseases.

The status quo won’t hold

If the many documented effects of climate change were not enough – all of which are disastrous at best and catastrophic at worst – pandemics such as the Covid-19 should force governments, corporations, and people to wake up and take stock of what’s at stake if we continue to take mild action against planetary plunder. After all, the evidence and prognosis are clear – pandemics are not the fault of wildlife, it is human activity that is facilitating and enabling the emergence and spread of such diseases. If biodiversity were preserved and animal habitats left as it is, coronaviruses would not cause mayhem and deaths. 

When humans disrupt the ecological balance, mindlessly and ruthlessly exploiting land and its resources, deadly consequences will naturally follow, many of which will spiral out of control. It is our hubris that blinds us to the physical law of action and reaction. To ignore the cumulative effect of global warming, deforestation, pollution, and rampant destruction of the natural world is to be caught flat-footed and napping when pandemics like this one hits because science and technology can only do so much. Other phenomena like frequent droughts, cyclones, floods, unpredictable weather patterns, and extreme weather events are already happening, and yet meaningful action is yet to be even discussed, forget implemented.

If Covid-19 should teach us anything, it is to learn its harsh lessons and adopt long-term solutions to combat recurrences. This includes preserving biodiversity and the fragile ecological balance of our planet, taking drastic action against climate change to limit the global temperature rise to 2 °C at a minimum, limiting human activities and land use in areas that are the habitats of animals, and protecting wildlife. It also means tackling healthcare inequalities and guaranteeing basic, liveable income to every human on this planet so that an unknown disease doesn’t wreak havoc on the lives of the most underprivileged of us. The migrant-worker crisis in India precipitated by the lockdown has shown the complete lack of social security and human dignity provided by the state when that is their main responsibility. 

The disease may have been generated in China but the abysmal handling of the pandemic here raises questions as to what kind of society we live in and what kind of society we want to be. What is clear is that the world can ill-afford another pandemic and it definitely cannot afford to degrade the environment any further. The key question remains: is it too late for an unprecedented global action to save the planet? Without being overly fatalistic, the answer is inching towards a yes.