Worldwide it is estimated there are up to 850,000 undiscovered viruses in mammals and birds with the ability to make the jump to humans. Known as zoonotic diseases or zoonoses, these types of animal-human viruses account for 70% of emerging diseases (for example, Ebola, Zika or Nipah encephalitis) and almost all pandemics, including influenza, HIV/AIDS and COVID-19.
Perhaps the most alarming statistics reveal that so-called “spillover” events from animals to humans are becoming more frequent. This stands to reason, since the human-made factors driving the spillovers are accelerating too: soaring demand for animal protein; intensification of agriculture; destruction of remaining wildernesses. Industrialisation of global food production has been found to produce less sanitary conditions, while sophisticated food supply chains can spread a virus across the globe in a short period of time — perhaps even shorter than its incubation period. Zoonosis risk has also increased thanks to a boom in both the legal and illegal wildlife trade; and the warmer, wetter and more extreme weather events caused by human-induced climate change.
This article explores how policymakers are reacting to the arguably overdue realisation that we are entering a “Pandemic Era”, and what more could be done to limit the risk of new zoonotic diseases emerging in future. These potential solutions fall into two broad categories: identifying dangerous viruses before an outbreak, and treating the risk factors bringing us into contact with them in the first place.
Too often zoonotic disease policies have focused purely on containment once an outbreak has already occurred. Proactively testing for zoonotic viruses remains patchy, whether in wild animals, infected domestic animals or at likely spillover sites. The bulk of pathogen-identifying laboratories are in wealthy Western countries rather than in or near zoonosis hotspots. This can make diagnostics expensive and cumbersome, for example thanks to the need to shuttle teams and samples between distant locales.
A more flexible, decentralized approach has been called for, providing training to local health officials, education to communities, and widespread distribution of modern biosampling technology which has become increasingly affordable to use in remote locations. This should be coupled with more centralised elements such as a publicly accessible global database of emerging pathogens and regional labs for large-scale tasks such as biobanking of cell cultures and research into virus evolution.
In Uganda, environmental health practitioners monitoring the food chain have had success in preventing zoonoses such as Ebola. In Bolivia, an investigation of howler monkey deaths detected the yellow fever virus and prompted a vaccination drive of the local population.
Equipment and training have been successfully transferred to remote hotspots, for example during the Ebola or Zika epidemics. But again, this was reactive only once an outbreak had occurred.
An existing model for a worldwide zoonoses database might be the GISAID EpiFlu repository, a global initiative developed for sharing influenza virus sequence data which is currently also documenting SARS-CoV-2.
Efforts at coordinated international responses to zoonoses have been developed before, for example a UN-backed framework after the bird flu pandemic. Meanwhile, WHO’s International Health Regulations (IHR) attempt to bind states to improving domestic detection of diseases and empower WHO to seek non-state (“unofficial”) evidence on outbreaks.
Such frameworks proved toothless during the early stages of COVID-19, however, as the Chinese government seemed willing to detain healthcare workers warning of a new virus threat rather than passing on information to WHO in a timely manner. Between the known first cases and the sharing of the COVID-19 genetic data, at least a month was lost.
Deeper and more effective global collaboration is required. IPBES, an independent body advising on biodiversity and ecosystems, has called for a high-level intergovernmental council on pandemic prevention to coordinate strategic research, monitoring, and ultimately setting binding targets for countries to meet. The UN Environment Program promotes the expansion of a “One Health” approach, with practitioners across disciplines working together on human, animal and environmental health.
On March 30, more than 20 world leaders signed an op-ed published in media around the world calling for a “new international treaty for pandemic preparedness and response”. Such a treaty would make governments “better prepared to predict, prevent, detect, assess and effectively respond to pandemics”, they wrote. It would be “rooted” in WHO’s constitution and “underpinned” by the IHR. Among other things the idea would be to foster collaboration on alert systems, data-sharing, research and diagnostics, and specifically mentions a “One Health” approach.
However, it is worth reflecting on the fact that this proposal emerged in media op-eds rather than through diplomatic or institutional channels. For the big question is how to convince geopolitical rivals to act in good faith within a common framework. China and its mainly Western adversaries increasingly appear to operate in antagonistic silos — exemplified by the reaction of the US and 13 of its allies to the latest report in the WHO’s investigation into COVID-19’s emergence in Wuhan, implicitly accusing China of withholding “access to complete, original data and samples”, and by the pledge by the WHO’s director-general to carry on the investigations.
During Donald Trump’s presidency, the vulnerability of funding streams for pandemic prevention was laid bare. Federal funding was removed from the PREDICT program, a branch of USAID, and the EcoHealth Alliance, both researching zoonotic diseases. Ultimately the Trump administration pulled out of WHO entirely.
The “mainstreaming” of pandemic prevention funding has been urged, building costs into consumption, production and government budgets worldwide. If the harrowing experience of COVID-19 proves insufficient motivation, advocates suggest further cost-benefit analyses to convince governments this is a sound investment. On a local scale, communities in zoonotic hotspots can be presented with similar arguments to convince them to abandon risky behaviours, such as trading wild meat or unsustainable agriculture. These should be coupled with incentives by providing appealing alternatives for both local diets and income.
A cost-benefit analysis on pandemics made by the World Bank in 2012 estimated that global investments of $3.4 billion would be required to avert losses due to pandemics that the Bank estimated at around double this investment. As COVID-19 has proved, this estimate was actually a huge under-statement, with global economic losses measured in trillions of dollars, making the cost-benefit analysis of prevention and detection even clearer.
Over one-tenth (3.3 million square kilometres) of wilderness areas have been lost since the early 1990s. Animal populations in these undisturbed wildernesses are often “reservoirs” for viruses with which humans have not yet come into contact. Furthermore, disruption or fragmentation of wild ecosystems has been shown to often benefit zoonotic species — for example, rodents are associated with more than 80 zoonotic diseases and also tend to adapt more quickly and increase in number following habitat disruption.
The main reason for habitat destruction is land-use change, particularly from forest to agricultural land. Demand for new cropland and pasture is driven by population growth and by higher demand for some food products (especially rising meat consumption in developing countries), but also poor farming practices leading to land degradation. Drought and desertification, exacerbated by climate change, is also causing losses of 12 million hectares of farmland per year, capable of growing 20 million tonnes of grain.
Global coordination on habitat support is growing. Over 50 countries have now pledged to protect 30% of their land and coastal waters by 2030, including EU member states, the UK, Canada and many African and Latin American countries.
But conservation alone will not work without transformative thinking around food production. This could mean policies encouraging behaviour change, such as taxes on meat consumption or livestock production, and education for both local producers and global consumers. Solutions may also be technological, such as better methods for raising yields and protecting soil, genetically modified crops, lab-grown meat or other substitutes, and vertical farming.
The world actually reached peak deforestation in the 1980s, and many regions are seeing an increase in forest cover as afforestation efforts balance out losses. Over four decades, China has sought to tackle ecological problems such as desertification, soil erosion, flooding and dust storms with the “Conversion of Cropland to Forest Program”. Deforestation targets have been met elsewhere by working with local communities, for example the Cocoa and Forests Initiative helped halve deforestation in Côte d’Ivoire and Ghana between 2018 and 2019.
Crucially, the focus is shifting from mere tree planting to the creation of genuinely natural habitats that can act as refuges for (potentially zoonotic) species. The global “rewilding” movement to restore large-scale wildernesses and connect fragmented habitats is growing rapidly — marking the first “World Rewilding Day” in March 2021.
The legal trade in wild animals and meat has grown five-fold in 14 years, estimated to be at $107 billion in 2019. Illegal trade has been estimated between $7 billion-23 billion annually. This boom can be attributed to the increasing ease with which wealthy consumers are able to buy these “luxury” products from previously remote producers. The wildlife trade faces limited global regulation making disease monitoring problematic. Wildlife markets — where live wild and domestic animals mix closely with humans — are some of the riskiest places for zoonotic viruses to spread.
Any solutions in this area would have to involve enforcing global standards on the trade in wildlife, with consistent monitoring from “farm to fork”. Again, training and education for local producers and traders is important. More extreme measures include prohibiting the trade of species with a high zoonotic disease risk and closing specific high-risk markets. Tougher policies come with the risk of driving further trade underground.
A model that has been suggested is the Convention on Trade in Endangered Species (CITES). This offers varying degrees of protection to about 5,800 animal species, based on the risk trading poses to their survival in the wild. CITES has never dealt a killer blow to the endangered wildlife trade, and there are again concerns that it has limited influence on powerful countries such as China. However, one study suggests that just by making it harder to trade zoonotic species via regulation would reduce the risk of a deadly zoonotic jump being made.
There is no magic bullet for stopping zoonotic diseases blowing up into pandemics. Better global governance, funding and monitoring can be put in place. But the issue is enmeshed with other policy problems, such as biodiversity loss and food supply. Geopolitical rivalries, principally between China and the US and its allies, also hinders genuine global cooperation, with the COVID-19 crisis stoking as many recriminations as it did calls for global unity. But without advances on all fronts — local and global, across many sectors and disciplines — the outbreak of zoonotic diseases in this “Pandemic Era” looks set to continue.