EXPLAINER

Conserving Biodiversity to Mitigate Pandemic Risks

Thousands of undiscovered viral species of mammals and birds have the capacity to transmit diseases to humans. Photo credit: F. Ricciardi.
Thousands of undiscovered viral species of mammals and birds have the capacity to transmit diseases to humans. Photo credit: F. Ricciardi.

To prevent the emergence of a new pandemic, monitoring of pathogens must be supported by socioeconomic solutions that protect biodiversity.

Introduction

Zoonoses or diseases that are transmissible from animals to humans are not a new threat. In fact, many of the recent pandemic diseases originated from a spillover of pathogenic organisms such as bacteria or viruses from wildlife. Unfortunately, the exponential growth of human population, the encroachment on previously untouched natural areas, and other major environmental changes have dramatically increased the potential emergence of these diseases.

To reduce these risks, it is critical to re-think our usual risk mitigation approach to pandemics. Surveillance of pathogens in wildlife and human populations is not enough. Mitigation through specific actions related to illegal wildlife trade, agri-business, tourism, and transport infrastructure planning are fundamental steps that need to be considered.    

Why Existing Risk Mitigation Efforts Are Not Enough

A major global health and economic burden, zoonotic diseases have caused millions of deaths every year and hundreds of billions of US dollars of economic damage in the past 20 years. The recent novel coronavirus disease (COVID-19), for example, may eventually cost the global economy between $5.8 trillion and $8.8 trillion in losses or 6.4% to 9.7% of global GDP, according to a recent Asian Development Bank (ADB) report.

Current economic responses mostly focus on mobilizing resources for post-outbreak response. Meanwhile, the risk mitigation measures implemented at the initial stages of emerging infectious diseases are mostly limited to the surveillance of pathogens both in wildlife and human populations living in riskier areas.

Table 1. Stages of Pandemic Emergence

Stage 1:

Pre-emergence

Stage 2:

Localized emergence

Stage 3:

Full pandemic emergence

The pathogen is still in its natural “reservoir” of wildlife hosts.

There is a spillover of a wildlife (or livestock) pathogen to humans. Causes range from handling of butchered wildlife to exposure to wildlife markets or livestock farms, or in the wild. Outcomes may vary from small clusters of human infections to large outbreaks, some with limited person-to-person transmission (e.g., Ebola virus) and some without.

There is sustained person-to-person transmission and large-scale spread, often aided by global air travel (e.g., SARS, COVID-19) or the international movement of reservoir hosts or vectors through trade (e.g., West Nile virus).

Source: The Lancet.

Monitoring pathogens is necessary; however, it does not prevent the emergence of a new pandemic (moving from Stage 1 to Stage 2) because the risk factors remain. As highlighted by the Global Virome Project, there are 1.6 million undiscovered viral species of mammals and birds. Around 650,000 to 840,000 of these have the capacity to transmit diseases to humans.

On top of this are cases where authorities and communities ignore alerts coming from scientists about the high likelihood of a dangerous pathogen emerging from wildlife.

Drivers of Disease Emergence

Aside from monitoring pathogens, it is also necessary to mitigate the drivers of disease emergence such as population growth, expansion of agricultural and livestock areas into natural habitats, deforestation, increased contact with wildlife pathogens reservoirs, growing wildlife trade, and the rise of bushmeat hunting and consumption. To do this, multiple dimensions of socioeconomic development need to be taken into account.

Demand from a growing population and various environmental challenges, like climate alterations and frequent weather anomalies have changed the landscape of agri-business in Asia. Already the world’s largest agricultural market, Asia’s population is expected to grow to about a billion more by 2050. With these, the region is seen to account for half of the global increase in annual beef and poultry consumption in the next 20 years. To sustain this need, food production will have to increase significantly.

As arable land areas decrease, the pressure on the remaining natural habitats will surely increase. Studies have shown that high agricultural economic potential zones can overlap with high biodiversity areas. It means that there is an economic stimulus to convert these natural areas into croplands to boost agricultural production. Southeast Asia, for example, has already lost 293,000 square kilometers of forest cover to agriculture expansion.

Figure 1: Spatial association between endemism richness and potentials for a cropland expansion and intensification

High–high clusters indicate hotspot locations (red), in which areas most suitable for expansion/intensification of cropland are significantly associated with high values of endemism (species restricted to a particular geographic region). Source: Nature Communications.

Further encroachment into forests with high biodiversity will increase the risk of contacts with zoonotic pathogens and a potential spillover into humans or livestock. Considering the limited monitoring of pathogens and the high volume of trades for agricultural commodities, such event will have dramatic consequences.

Current development estimates highlight that 25 million kilometers of roads will be added worldwide by 2050. Ninety percent of these will be in developing countries, including many regions that sustain exceptional biodiversity, such as the Amazon, Borneo, the Congo Basin, and the Greater Mekong Subregion. Opening and fragmenting high biodiversity areas with new roads will almost inevitably cause human encroachment that would drive agricultural and livestock production. This would significantly increase the risk of contact with wildlife and the probability of a pathogen spillover. Unfortunately, access to roads could also increase the trade of bushmeat and wildlife products.

Figure 2: Roadless areas distribution in Asia

In Southeast Asia, roadless areas are still present in Borneo, Papua New Guinea, and Myanmar.
Source: Resource Watch.

The relationship between infectious diseases and altered climate patterns is not well understood yet. However, studies on seasonal flu can give an insight into what may occur with related diseases. In temperate parts of the world, flu exhibits strong seasonal patterns and tends to peak during winter. There is a possibility that the virus survives better in colder and drier conditions. Since people tend to stay indoors more, it is possible that they may infect others more easily, given the shortened physical distance.

In the warmer tropics, on the other hand, flu season tends to spread out throughout the year, with some spikes during the rainy season. Some experts suggest that climate change may cause outbreaks in temperate regions to become less intense but more evenly distributed across the seasons.

What is likely to happen with other viruses is difficult to predict, as they may vary in terms of climate preference and spreading modalities. However, it is likely that climate change can have a role in increasing the risk of further spreading disease.

Pushing many species on the brink of extinction, the trade of wildlife and its derivatives, legal or illegal, is a market worth trillions worldwide. The link between illegal wildlife trade and epidemics has already been confirmed on many occasions. Several pathogens have been detected in wildlife specimens traded worldwide. The disease transmission does not only cause human disease outbreaks but also threaten livestock, international trade, rural livelihoods, native wildlife populations, and the stability of ecosystems.

Table 2: Some of the pathogens diagnosed in illegally traded wildlife species or in humans or domestic animals in contact with them

Category

Pathogen

Species affected

 

 

 

Bacterial

Chlamydophila psittaci

Wild birds, humans

 

Salmonella sp.

Humans

Endoparasite

Opisthorchis sp.

Humans

Viral

Avian influenza

Wild birds, domestic poultry

 

Newcastle disease

Wild birds, domestic poultry

 

Rabies

Wild carnivores, domestic pets

 

Simian foamy virus

Humans

Adapted from National Center for Biotechnology Information.

The original host for COVID-19 was likely bats, but an intermediate host was probably involved in the transition to humans. At the time of writing, there is considerable speculation that this was a pangolin. Trading pangolins is illegal but persists because their meat and scales are highly valued. 

Regardless of the species involved and the exact geographical origin, COVID-19 demonstrated the urgency of combating illegal wildlife trade.

Proposed Solutions

Strengthen the planning and design of infrastructure, and avoid encroachment into natural forests, especially in biodiversity-rich areas.

Environmental considerations often come into discussion very late during infrastructure planning. In some cases, the destruction of natural habitats is seen as a “necessary cost” on the way to economic development. Road alignments are often prepared following engineering constraints and cost-saving considerations. Environmental assessments normally come at a later stage, when the probability of avoiding environmental damages are almost negligible.

The cost considerations, however, very often fail to include appropriate values on the ecosystem affected and are too short-sighted to include indirect impacts that very often go very far beyond the infrastructure actual footprint. For example, scientific studies have recently highlighted that out of a total planned investment of $27 billion in 75 road projects in the Amazon, 45% of them were not financially viable if environmental costs were properly calculated.  In addition, choosing a more optimal subset of roads could have delivered 77% of the economic benefits while incurring just 10% of the total estimated social and environmental costs. These costs, in areas of high zoonosis spillover risks, could be even higher.

Government and infrastructure planners need to be trained with targeted capacity building sessions to strengthen their understanding of the environmental, social, and public health implications of their choices. The expansion of agriculture and livestock farms near natural areas should be prohibited, leaving space for environmentally sustainable activities. Road, rail, and other transport projects need to be better planned, incorporating green infrastructure design to preserve natural habitats and biodiversity.

Create and develop country-specific Pandemic Risk Maps.

Each country needs to map key biodiversity areas vis a vis agriculture/livestock zones.  There is still time to modify the areas planned for agricultural clearance and to move them somewhere else. Integrating living landscape with infrastructure projects must be prioritized. 

The COVID-19 pandemic has shown that limited pathogen surveillance can have dramatic consequences. Even if global maps of risks are already available, each country needs to know which specific areas need attention to make their development compatible with nature conservation.

Likewise, research activities focusing on the discovery of potential new pathogens needs to be sufficiently funded.

Improve and strictly enforce laws and policies to regulate wildlife hunting, trade, and collection.

In addition to reducing the risk of pandemics, regulating wildlife trade will help conserved species and protect biodiversity. 

In the Philippines, the Department of Environment and Natural Resources, supported by ADB and other partners through the Global Wildlife Program, is revising the country’s 18-year old Wildlife Law to increase criminal penalties for wildlife trafficking and trade, as well as to increase public awareness to reduce the demand for products from wildlife. Efforts such as these need to be scaled up internationally. Global agreement to fight illegal wildlife trade is also critical.

In addition to capacity building and training for enforcement officers, new technologies must be leveraged to strengthen crime monitoring. For example, machine learning and artificial intelligence can mine a large amount of information to identify trade traffic routes. Fast and cheap DNA barcoding tests can also be used when the traded species comes in the form of derivatives, such as meat, feathers, or other products.

Re-think tourism focusing on environmental sustainability and local communities’ culture and traditions.

The increase in tourism worldwide has serious consequences on the environment and on wildlife. In some areas, local communities hunt wildlife to satisfy the appetite of foreign tourists. Eco-friendly and socially responsible tourism enterprises need to be encouraged and destructive tourism practices should be prohibited.

Fruit bats collected to be sold to tourists in North Sumatra, Indonesia. Photo credit: F. Ricciardi.

Conclusion

If the world continues on business as usual, it is merely a matter of time before the next pandemic—possibly the most unforgiving—will emerge.

Thus far, global efforts for emerging infectious diseases have been reactive or focused on post-outbreak measures such as control and containment, quarantine efforts, and vaccine development. Their usefulness will probably be limited for the next pandemic.   We need to plan for emerging infectious diseases like we do for other natural disasters: focused on mitigating risks, improving safeguards, and increasing resilience.  

A paradigm shift is needed because humanity and economies depend on healthy ecosystems, and not vice-versa.

 

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Ask the Experts

  • Francesco Ricciardi
    Environmental Specialist, Sustainable Development and Climate Change Department

    Prior to joining ADB, Francesco worked as a researcher focusing on the impact of pollution on natural ecosystems and wildlife. After leaving academia, he has worked as environment, ecology and biodiversity consultant in several projects around Asia, including energy plants, coastal infrastructures, and natural resources. He is also a published underwater and wildlife photographer.

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  • Asian Development Bank (ADB)

    The Asian Development Bank is committed to achieving a prosperous, inclusive, resilient, and sustainable Asia and the Pacific, while sustaining its efforts to eradicate extreme poverty. Established in 1966, it is owned by 68 members—49 from the region. Its main instruments for helping its developing member countries are policy dialogue, loans, equity investments, guarantees, grants, and technical assistance.

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   Last updated: June 2020



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