Redefining our relationship with nature to avoid future pandemics

Abstract

Emerging infectious diseases that progress to pandemics are becoming recurrent, causing serious impacts that exceed our health and well-being. Despite its unheard of magnitude, the COVID-19 pandemic is just one more in a long list of severe events that have stricken humanity in recent decades (HIV-AIDS, Ebola, Nipah, Hendra, SARS, Zika, H1N1 influenza, etc.) (1). Far from downplaying its importance, this magnifies it, given that even with repeated warnings we have failed to recognize the underlying problems and act accordingly, in advance.

Most recent human emerging infectious diseases are of animal origin, and in many cases linked to wildlife (1, 2). These emerging zoonoses are associated with land use change (e.g., deforestation for agriculture), the expansion and intensification of food-animal production (e.g., industrial-scale swine and poultry), and the use and consumption of wildlife (e.g., Asian exotic species markets) (2). All these activities are promoted by our growing consumption and share the common factor of favoring unprecedented and frequent contacts between multiple species, allowing an enormous diversity of pathogens to infect new hosts. Because of our demographics and globalization, once spillover (the initial jump from an animal to a person) has occurred, an infection can easily become an outbreak, and then a pandemic, spreading to and within urban areas through trade and transportation networks.

Although transmission of a virus with pandemic potential is still extremely rare, as with any selection pressure, the more common the epidemiological contexts selecting in that direction become, the greater the risk to all will be. This is a key element because we tend to oversimplify the agent-host-environment epidemiological triangle, thinking of systems as rules of three. However, this reductionism disregards the fact that diseases occur in complex systems. Thus, their understanding requires broader epidemiological intelligence, i.e., ecological and social contextualization, beyond the mere verification of overlap in time and space of pathogens and hosts.

In this sense, the One Health approach, which integrates human health into its ecological environment, is our most powerful tool because, by definition, it places us in a dynamic matrix. Whether or not it is obvious to us in daily life, our health is closely linked to, and depends almost entirely on, the health of the environment and the species with which we coexist. Biodiversity not only acts as a buffer by diluting or balancing the microbiome around us, but is central to the provision of life-sustaining ecosystem services (3). Some species, such as bats, are efficient controllers of disease-vector insects and agricultural pests, pollinate essential crops and disperse seeds that regenerate the tropical forests needed to regulate the planet's climate. Far from blaming them as scapegoats for incubating the ills that afflict us, we should value their contribution to ecological regulation that further enhances health. Essential contributors to human well-being, ecosystem services are valued at 44 trillion dollars annually (4) and their degradation or loss is an obstacle to the reduction of poverty, hunger and disease (3).

Conversely, dividing health into siloed compartments has made us more vulnerable. That the burden of response to disease emergence falls on public health systems, when the underlying etiology only touches on health, is a serious global deficiency. This became self-evident with the appearance of SARS-CoV-2 only 16 years after what should have been an alert of seismic magnitude, the SARS-CoV of 2003. If the root cause of coronavirus zoonoses is the close contact between taxonomically distant species and a value chain that often borders on illegality (or is outright illegal), then the prevention of future events depends essentially on reconciling competing interests (economic, political, health, environmental) by implementing One Health.

Even though there are important information gaps, what we already know gives us a clear advantage: it allows us to propose mitigation strategies. For example, in the last decade and through projects like PREDICT (5), we have focused on searching for and characterizing zoonotic viruses with pandemic potential in their animal reservoirs, before they become human pathogens. Following One Health principles, PREDICT delved into the dynamic relationships of disease emergence factors and, above all, into the socio-ecoepidemiological contexts in which they occur. Beyond the nearly 1,000 new viruses identified, including some particularly relevant ones such as Bombali Ebolavirus and Marburg virus in a new geographic area, PREDICT left a legacy of unprecedented capabilities in 35 vulnerable countries around the world. It also demonstrated the benefits of One Health concurrent surveillance, promoted harmonious and safe coexistence with wildlife in rural communities and identified wildlife trade as one of the activities with the greatest zoonotic risk but with little or no sanitary control.

Meanwhile, the Global Virome Project plans to spend a decade identifying all wild bird and mammal viruses with zoonotic potential (estimated at 500 to 700 thousand). Although there is no certainty that this viral atlas can anticipate "Disease X", it would at least broaden the horizons on problematic groups such as coronaviruses and allow anticipating diagnostic and therapeutic developments. Proof of its potential is that of the 177 coronaviruses described by PREDICT in animals and humans, 113 were new to science (5). In all cases, the aim is to move away from the traditional model of post-outbreak reaction and control, in favor of prediction and prevention.

However, it is increasingly clear that more is needed, and that without a profound and systemic social transformation we will remain trapped in the current vicious cycle that engenders pandemics. Experts predict that without a paradigm shift, "pandemics will emerge more often, spread more rapidly, kill more people, and repeatedly crash the global economy" (3). In 2019, another group of experts convened by the same UN panel cautioned that if we continue down this path we will be "eroding the foundations of our economies, livelihoods, food security, health and quality of life" (3). The good news is that if we set our minds to it and succeed in reversing the environmental damage caused by unsustainable production and consumption, we would simultaneously be mitigating the three greatest threats to our species: biodiversity loss, climate change and pandemics.

Given current knowledge we should avoid falling into the simplistic acceptance that since the risk of pandemics is uncertain we can only wait for one to strike before reacting. Estimates show that responding to control is 100 times more costly than investing in prevention (3). And that is without considering that, as a result of the disparate impact of COVID-19, 32 million people in the 47 least developed countries will be plunged into extreme poverty (6). What future response capacity will such impoverished countries have? Redefining our relationship with nature will allow us to stop pulling the devil by the tail within the timeframes set by the Pandemic Era.

Acknowledgments: F. Milano and P. de Diego for their critical reading and valuable suggestions.

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