COVID-19 is both a One Health disaster and opportunity

In this blog CE4AMR post-doc Jess Mitchell discusses COVID-19 through a One Health lens.  Why do we need to worry about bat’s strong immune systems? How do our disrespectful interactions with nature put us at risk of future pandemics, and interlinked global challenges?  Jess discusses these issues in the scope of recently published work with the aim of providing an accessible One Health overview of the COVID zoonosis, it’s links with global challenges including AMR, climate change and the potential to truly Build Back Better.

 

Let’s begin with bats

COVID-19 is a type of coronavirus that appears very similar to viruses carried by Horseshoe Bats in China, Cambodia, and Japan.  Bats are known as reservoir species for viruses and other pathogens (the generic term for microorganisms such as bacteria, viruses, and fungi, that cause disease).  This is because many infections appear to survive in bats without causing them harmful symptoms.  Bats have several adaptations to their immune systems which allow them to fight infections very effectively.  Firstly, they can quickly generate lots of antibodies which attack specific pathogens, secondly flight elevates body temperature to an almost feverish level which again helps fight off infections in general.  Finally, bats can limit the inflammatory response of their immune systems during infection, such that they are able to effectively fight off pathogens without causing their bodies to become exhausted.

But why is this important?  Well, heightened immune functioning is great news for bats, but less so for other species such as humans.  This is because bat viruses (and other pathogens) must become very hardy.  To get ahead of the bat’s immune defenses these viruses must multiply and grow rapidly once they infect a host.  In bats this is not a huge problem but when a bat virus spills over into other hosts, like humans, it can tear through our weaker immune systems before we have a chance to respond. This is what we have seen with COVID-19. Of course, we do not know for certain that COVID-19 came directly from bats, but the genetic data give us pretty good reasons to assume.  We also know that many of the first humans infected with COVID-19 had visited the wet market in Wuhan China, where a variety of wild animals are sold for food and traditional medicines.  This wet market did sell bats so it is possible that the virus could have spilled over from bat to humans there.  An alternative explanation is that the virus first infected another type of animal, an intermediate host, and then spilled over to infect humans.  For a more detailed discussion see Tiwari et al. Regardless of the exact pathway the virus took to spill-over from one species to another (zoonosis), we are pretty sure it happened because of our increasingly invasive behaviour into the habitats and ecosystems of wild animals.

COVID appeared due to ignorance of One Health

Over the past several decades humans have encroached on many habitats at an alarming pace, destroying biodiversity and ecosystems.  At local level this is often linked to population growth and the expansion of cities and settlements.  However much of our encroachment is not driven by local individuals but by consumerist practices managed by humans far away from the habitat itself.  For example, logging of rainforests to provide timber, pasture for meat producing animals, or mining access.  Such activities benefit the lives of those purchasing the furniture, beef burgers, gadgets, and other resources.  However, at local level the impact is much more threatening.  Indigenous communities whose land rights are ignored, are usurped to make way for machinery and access roads, pushing whole settlements into new territory where their interaction with nature becomes much more intense.  Communities are pushed into closer contact not just with wild animals from which disease can spill-over into humans directly, but also with vectors, biting insects like mosquitos, which can transfer disease between animal species and humans. Waste and run-off from farming and mining can move downstream to pollute the water of local communities. This forces humans, wildlife, domesticated animals, and vectors to share water sources which creates opportunities for diseases to spread through cross-contamination.  Pollution itself can also cause genetic changes in pathogens which can cause diseases to resist treatment (AMR) or become more likely to infect new species.

As large companies profit from habitat destruction local ways of life including employment and food production are challenged.  This increases human-environment conflict meaning local people may hunt bushmeat as food or for profit, utilize agricultural medicines inappropriately to accelerate the growth of their livestock, contribute to habit destruction as they create new settlements, and travel farther for work.  These actions directly increase the risks to local people and their livestock of contracting pathogens such as COVID-19.  However, the impacts do not stop at local level.  If bushmeat, poaching hauls or farmed animal produce are sold on the risk extends to the wider population.  We know that the Wuhan wet market sold a variety of live wild and farmed animals so the risk of wild pathogens infecting city dwelling humans suddenly becomes plausible.  Once taking hold of a city-based population it was a matter of months before the virus hit pandemic status spread by international travel across the globe.  Instantly this shows us how important human-wildlife interactions are to everyone, and how consumerist behavior in disparate countries can directly facilitate the zoonosis and spread of new pathogens at international level.

This is an extreme example, and it is important to stress that most wet markets are small scale and likely to include preserved animal products from which the risk of zoonosis or infection is greatly reduced.  What can be generalized is that the speed of our industrial and consumerist habits far exceeds the natural process of evolution whereby pathogens may steadily move between species and some level of immunity can be acquired. No matter what vaccine developments we can fast track, history will repeat itself if we do not challenge the root cause of the pandemic.  Zoonoses happen when animal species (including humans) are suddenly forced to interact very closely.

COVID and similar zoonoses can only be controlled by true One Health action

It is this One Health narrative that has received little attention in the reporting of COVID-19, or indeed earlier pandemics.  The Reservoir multimedia story from 2018 discussed contextualized zoonosis and spillover events through a One Health lens way before we faced  COVID-19. Unfortunately, it appears we still have a lot to learn.  During this current pandemic we have focused on finding vaccines and managing COVID’s spread through good hand hygiene, which are of course important steps.  However, we also need to minimize the risk of another zoonotic event by protecting our animal and environmental health. China has discussed the option to close wet markets and limit the trade in wild animals. Although some may see this as a positive step, as it does deal with  areas of concern such as animal welfare, it doesn't represent a holistic One Health approach of joining up human, animal and environmental issues. For example, closing wet markets will not address the causes of why people poach, traffic, or consume wild animals.  Additionally, in many parts of the world wet markets are essential community practice and bushmeat is a sustainable source of protein.  Global bans could thus push some communities into increased poverty, malnutrition, and economic challenges.

One holistic solution is to engage people with the One Health dialogue.  There has been huge progress in translating Climate Change science into accessible language that allows non-academic audiences to understand and see where they fit into the problem.  We can localize climate impacts so that global audiences understand why they should personally make behavioral changes, and what the benefits of these changes are for humans, animals, and the environment. We can also exert pressure on the businesses, politicians and individuals who are responsible for widespread climatic damage via their unsustainable practice. We drastically need to extend this thinking to One Health topics, particularly zoonoses.  This approach would be locally specific and mean different communities need to take different action.  For a forest-dwelling community this may mean limiting your bushmeat consumption and employing stricter hygiene practices.  For a western consumer it may mean overhauling purchasing habits to ensure your goods are sourced from well managed areas with strong environmental and ethical policies.  Wherever you live, you may need to lobby for change at policy level.  We have seen the Climate Crisis enact this kind of bottom-up pressure for change across the globe, whilst the interlinked challenge of antimicrobial resistance (AMR) is also benefiting from community engagement interventions. A key learning from these challenges is that to create behavioral changes, people must be fully engaged with a problem.  Awareness raising and increased knowledge alone are not enough.

What are the wider benefits of One Health action on zoonoses?

It’s not just pandemics that could be alleviated through One Health action. As we have mentioned, many of the behaviors implicated in zoonoses also exacerbate the climate crisis (deforestation, mining, unsustainable agriculture, urbanization etc.) so working toward locally appropriate solutions does have a duel benefit.  Climate and zoonoses are also interlinked, new evidence suggests warmer temperatures can speed up the ability of pathogens (viruses, bacteria etc.) to change or evolve, and make it more likely that they will infect other species.

Infectious diseases in general could become better-controlled by the implementation of good hygiene practices, environmental respect, and distancing between humans and both wild and domesticated animals (in terms of water sources and sleep quarters for the latter).  We also need to learn about what best practice means in different environments.  We know temperature, humidity, and climate impact on diseases.  The communities living in these areas will be experts in how to manage their own disease risks and western organizations would do well to listen to this expertise.

We could also make great strides in tackling another interlinked and burgeoning global crisis, antimicrobial resistance (AMR).  Pathogens are becoming increasingly resistant to our current treatment options (including antibiotic medicines) because these drugs have been used inappropriately and unnecessarily. Like that bat’s hardy immune system, this malpractice only serves to challenge the pathogens to find ways to survive and adapt. AMR is currently considered in the light of its human impacts which are concerning, we face the prospect of being unable to treat common infections, making medical processes such as surgery and cancer chemotherapies increasingly risky.  The One Health approach, though, moves beyond human health to consider the wider impact on our planet. Taking a One Health approach is critical in the fight against AMR because resistant pathogens can survive in humans, animals and even the soil and water around us. AMR is closely linked to zoonoses as unregulated use of antimicrobials in agriculture is a key driver of resistance.  This practice tends to happen when food producers are under pressure to meet increasing consumer demand for food and do not have high quality pasture to allow slower, safe growth of animals.  In these instances, antimicrobial treatments are often used as growth promoters or as prophylaxis to prevent, rather than treat, disease outbreaks.  Unfortunately, antimicrobial use in livestock can allow resistant genes to spill over into the environment and spread, such that resistance moves from community to community across the globe.  A fruitful avenue of action here would be to better link the Sustainable Development Goals with AMR indicators as discussed in a previous blog.  However, engagement with One Health would allow communities across the globe to understand how their personal actions impact on a variety of issues.  COVID-19 has given a face to One Health challenges, a face we cannot ignore.  Hopefully, a learning from this pandemic will be a greater appreciation for the interlinkages between human, animal and environmental health, and a translation of this appreciation into action.

Summary

COVID-19’s jump to humans was in many ways inevitable because of our growing disrespect for the ecosystems around us.  But this blame cannot be localized to the communities in closest proximity to the site of zoonosis. Rather we need a global focus on One Health, the interplay between human, animal, and environment health.  One Health ignorance leads to exploitation of our ecosystems because we can disregard our human reliance upon them.  While we must consider the needs of a growing population for food and shelter, we cannot loose sight of the potential impact that unsustainable farming and deforestation have on our long-term planetary health. COVID-19 is a reminder that we are equally vulnerable to a microscopic part of these wider eco-systems.  However, in our aims to build-back-better, One Health awareness could become the silver lining of this pandemic.  Greater understanding of how human, animal, and environmental health are intertwined could change those behaviors and attitudes which drove us into this pandemic, protect us from future zoonoses, infectious diseases, and other challenges including Climate change and AMR.

 

Opinions expressed within this article are those of the author and are not necessarily representative of CE4AMR as a network.  If you would like to contribute a blog or opinion piece regarding the inclusion of AMR within the SDGs or Build Back Better dialogue please contact Jess (j.mitchell1@Leeds.ac.uk).

Photo credit: Nichola Jones