Nobel laureate Joshua Lederberg famously said that "the single biggest threat to man's continued dominance on the planet is the virus." The biological entities called viruses exist in the twilight zone between life and non-life and remain an elusive subject of evolutionary study. While the invisible biotic world of microbiology is often synonymous with dread, only around 1% of all microbes can actually cause disease in humans. Within the realm of microbes, bacteria, unlike viruses, have found redemption in our contemporary worldview through their positive role in digestive processes. Viruses have received less attention for their constructive role in ecological sustainability but their virtue should not be completely eclipsed by their vice. Nevertheless, Lederberg's words appear prophetic in our current pandemic crisis, even though humanity has endured numerous prior pandemics in history. What makes the situation different now is the speed of contagion spread due to globalization, as well as the economic and social impacts which are consequent as a result.
Enigmatic origins: wet markets, lab accidents and Tiger Kings.
The origin of the novel coronavirus that causes COVID19 disease is widely believed to be a wild mammal that likely carried the virus and transmitted the virus to humans in the Wet Market of Wuhan, China in the autumn of 2019. There is also some (as yet unsubstantiated) evidence of accidental release of the virus during virology research at China's only Biosafety-4 level laboratory, which happens to be in Wuhan -- only 200 meters from the entrance to the city's Wet Market. It is important to note that peer-reviewed research has shown that the virus itself does not appear to be genetically engineered and any connection to a lab release is purely from a scientific research origin of the natural pathogen. Regardless of the human exposure pathway, the virus has strong similarity with coronaviruses found in bats, and research undertaken by the Ecohealth Alliance suggest that bats have the largest virus reservoir of potential spillover to humans. The next question pertains to how transmission occurs. No doubt any human interaction with wildlife raises risk but this rise is particularly higher when wild animals with dormant virus reservoirs are activated through contact with humans. This can happen through bushmeat consumption (as with Ebola), contact of wild fauna like ducks and geese with domestic chickens (avian flu) or captive pet and meat sale markets (as may be the case with SARS or COVID19). Stress factors which can activate viruses definitely include captivity and close proximity with other animals, as is often the case in markets and during pet transport. However, this could conceivably happen with zoos and domestic pet populations as well.
Asia and Africa should not be singled out as the locus of zoonotic exposure, as many in the popular media are doing. Viewers of the new Netflix hit docudrama Tiger King should consider the wide exposure potential of zoonotic diseases transfer from the exotic pet and entertainment industry, which is widely practiced in the United States and Europe. A shocking fact to note is that there are now more tigers in captivity in the United States than in all of the world's wild habitats! Add to that the reptile gardens and poorly regulated exotic pets owned by individuals in their back yards and basements and the potential for a pathogenic zoonotic event happening the United States cannot be underestimated. Such was the case in the epic Hollywood film Outbreak in which a pet monkey spread a virulent hemmorhagic fever. Factory farming can also be a disease exposure accelerator as was the case with Swine Flu a decade ago which originated in Mexican pig farms. Disease origin is thus complex and all of humanity at some level is culpable in exacerbating our risk exposure through the way we are interacting with our fellow planetary organisms.
Global environmental change and pandemics
The role of climate change and habitat loss with regard to zoonotic disease prevalence is more complex and deserves greater care in policy formulation. Vector-borne diseases such as malaria are dependent on climatic ranges. Natural and human-made habitats can be conducive to their prevalence. A warming climate will on the one hand increase the altitudinal and latitudinal range of certain mosquito species, while it may also lead to dryer soil conditions which are less conducive to mosquito larvae. The situation with regard to the impact of climate change on influenza and corona viruses continues to perplex researchers. The viruses tend to be seasonal in temperate climates but they are still active in warmer tropics and overall infection rates are comparable. Understanding virus vitality under different temperature and moisture must be an urgent priority for pandemic prevention.
Overall far greater research is needed before any definitive claims can be made about the linkages between global environmental change and the wide and complex range of zoonotic pathogens. What is clear is that wildlife management in the anthropocene must go beyond simply ascribing blame on habitat loss as there are contemporary pathogens such as Lyme disease which have a far more complex zoonotic transfer ecology. We also need to be more alert to the consequences of our interaction with other animals as global environmental change and population densities continue to exacerbate stress on organisms. In areas such as remote unpopulated forests, it may be easier to follow a preservationist path and have much less human-wildlife interaction to mitigate zoonosis. At the same time human engagement with wildlife for research is also important, since many organisms in biodiverse ecosystems offer great hope for both chemical and biological pharmaceuticals.
Human behavior and cultural bias
Anthropologists will remind us that cultural and subsistence aspects of some forms of animal consumption need to be reconciled with modern standards of health, hygiene and sustainable consumption metrics, but we must do so consistently and without prejudice and xenophobia. A key element of epidemic and pandemic prevention will be limiting the scale and extent of such interactions through protected areas management that considers pathogen exposure potential. Some measured level of zoonotic exposure can also build immunity to potential pathogens as was observed with some of the market vendors in Guangdong during the SARS epidemic. Key to balancing exposure immunity and disease spread potential is monitoring the serology of such populations regularly to identify any antibody anomalies as well as the virus reservoirs in animal populations.
Nevertheless, reducing animal-based diets as well as far greater care with pet health and their exposure to wildlife are likely to reduce chances of zoonotic disease transfer. However, there are also a range of disease microbes which can find their reservoir in soil, plants and fungi as well and the phenomenon of sapronoses (disease transmission from abiotic or non-living substrates) should not be discounted either in its pathogenic potency. Diseases such as tetanus have historically spread through such mechanisms widely before vaccines were found. In such cases environmental impact mitigation itself may not be adequate. We simply need to be vigilant and monitor the risks and the evolutionary processes which will always spring surprises on us through mutations and horizontal gene transfer (a phenomenon which has also led to the emergence of antibiotic resistance bacteria).
Humility about hidden dangers
Human disease development in the face of environmental change will require constant research, global coordination and data exchange to keep up with the speed with which ecology and pathogenic agents are changing. There are still immense unknowns in this field which continue to confound us. Consider the case of the infectious facial cancer which is destroying the Tasmanian devil population in Australia which is under threat of extinction from the disease. So far there is no linking of this disease to human activity nor has animal to human transmission occurred but the potential for such transfer deserves study. Viruses in plants are thus far not able to transmit to humans but they do seem to find their way into insects and there are potential pathways for pathogenic entry into human systems. Research under ice sheets has also discovered viruses and bacteria which could potentially be pathogenic when they are released to the environment due to climate change melting the planet's polar regions.
The advent of the anthropocene has made it even more incumbent upon us as a species to consider the feedback loops of impact on biological systems from our activities while recognizing that nature has its own agency too. Pathogens have impacted humans even when we had a relatively benign impact on natural systems in our earlier history. Sustainable coexistence with biological agents does, however, require much greater investment in knowledge transfer about the multiple pathways of exposure.
Virus inventories versus human surveillance
If we are simply to consider viruses (excluding other pathogenic agents like bacteria), there are around 220 known types of viruses that are known to cause disease in humans. However, there are an estimated 320,000 virus types just in mammals (based on statistical extrapolations). An estimate published in 2013 suggested that it would cost ~$6.3 billion to discover these viruses (or ~$1.4 billion for 85% of the total diversity). Currently, there is a fairly well-funded organization called the Global Virome Project which is undertaking such an inventory since 2018. However, several more years are needed before this project can show clear preventative results against pandemics.
There are also detractors of such virus inventory work who have feel that funds would be better spent on surveillance of disease clusters and better coordination across global hospital reporting standards. Such an approach could also be a safeguard against wider population exposure to pathogens from lab accidents which may ensue from the inventory research. Clearly, given the staggering economic cost of the current pandemic, investment in both inventory and surveillance approaches would be justifiable and far less costly than the trillions of dollars in bail-out packages being implemented over just a few months of this crisis. Furthermore, even if surveillance is a more urgent mechanism against pandemic spread, viral inventories might also have a side benefit of perhaps discovering some virtuous viruses in the process which help us with nanotechnology research.
Viral governance in the anthropocene
Our aim should be to ensure, as best possible, that no virus or pathogenic entity is "novel" in an age when we have so many analytical tools at our disposal. Developing such a knowledge base would be an essential step in then charting out our sustainable coexistence path with the biotic diversity on our planet. Greater coordination between major environmental research projects and public health research entities deserves immediate attention. Organizations such as the Ecohealth Alliance which focus on pandemic prevention already have a broad partnership base with international environmental organizations. The next step may be more specific project coordination and data collection with organizations such as the Global Environment Facility and its implementing agencies that particularly service the Convention on Biological Diversity, the UN Convention to Combat Desertification and the UN Framework Convention on Climate Change. There is good evidence for the systemic linkages between biodiversity, land degradation and climate change which in turn can be threat multipliers for pandemic vulnerability.
Finally, while current environmental indicators may seem to be improving in some areas as result of low human activity patterns in the pandemic, there is no room to be sanguine. Recovery from such disruptions in the anthropocene means finding an optimal path between caution and paranoia. We will need to find win-win opportunities for lifestyles with lower ecological impacts while still mitigating health risks that can spark survivalist selfishness. For example a return to using low carbon public transport with greater hygiene care while not impacting risks of future contagions. Ultimately, in the post-COVID19 anthropocene, global environmental governance mechanisms will need to be more tightly coupled with individual responsibility if we are to have an ecologically and economically efficient path forward towards sustainable development.
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Very interesting article Saleem. Here is some relevant news from the University of Maryland's research community: https://today.umd.edu/articles/predicting-covid-19-outbreaks-7dd0062a-d9f3-4a6e-aafa-cb5ab866f46a
Many thanks Sally - have shared this as well with my networks.