A recent study published in the Lancet Planetary Health Journal investigated the link between food systems, zoonotic diseases, and sustainability.
Study: Exploring scenarios for the food system–zoonotic risk interface. Image Credit: SerhiyHorobets/Shutterstock.com
Background
The global impact of the coronavirus disease 2019 (COVID-19) pandemic, caused by the sudden outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), underscored the need for investigating the drivers of zoonotic spillover events.
Spillover events occur for various reasons, including biodiversity loss, wildlife hunting, high habitat fragmentation, and agricultural inputs. The majority of these factors are connected to food systems. Thus the structure and characteristics of food systems can be seen as key determinants of pandemic risks. Therefore emerging communicable diseases should be addressed in the discourse of food systems to prevent spillover events.
Introduction
The COVID-19 pandemic has shown how public health is connected with ecological, economic, and societal vulnerabilities.
During the pandemic, most countries' governments have implemented various social restrictions to reduce infection rates and quickly contain the pandemic. However, these policies fell short due to the continual emergence of infectious SARS-CoV-2 strains.
The healthcare policies formulated to contain the pandemic did not consider the global food system, which is concerning because of its complex interaction with zoonotic outbreaks and infectious diseases. Food systems significantly vary in their production methods, governing policies, product varieties, and stakeholders. Hence, it is important to understand the risks of zoonotic disease from these various food systems.
About the study
The current study used a scenario framework approach to develop a qualitative blueprint of the variable impacts of multiple agricultural practices, diets, and land allocation patterns on zoonotic spillovers.
This approach will provide better insights into how food-related interventions and food policies affect zoonotic spillovers. Archetypal food systems were constructed based on the links between zoonotic spillovers and food systems.
A total of ten food-system-related drivers of zoonoses were categorized, i.e., biodiversity loss, fertilizer application, pesticide use, wildlife hunting, land fragmentation, water use, antibiotics use, livestock densities, farmworker densities, and aquaculture.
Based on a scenario framework, the extent of land use and agricultural practices were selected as the primary factors driving most of the variance in the ten food-system drivers and contributing differentially to sustainability.
Four archetypal food systems comprised structural characteristics of four unique global food-system narratives with varied risks and possible interventions that could decrease zoonotic spillovers. These systems were referred to as scenarios.
Study findings
This study focuses on the existing typologies and not on future developments. The experts ranked the ten individual food-system drivers in the four scenarios. The four scenarios reflected the existing food systems, and unique socioeconomic and environmental impacts and zoonotic spillover risk levels characterized each.
The overall risk of zoonotic spillover was assessed based on the product of the probability of an event occurring and its impact severity. A uniform degree of severity for all factors was assumed.
Although zoonotic spillover risk was quantified based on the potential for the occurrence of events, some factors were found to be less risky than others. For instance, irrigation was less risky, with a maximum score of three out of five.
The American and Australian populations consume a high meat diet, so the production volume of livestock is high. The industrial animal-based scenario indicated that a high meat diet entails high zoonotic spillover risks.
This scenario was associated with multiple food-system drivers, such as the high use of water, fertilizers, antibiotics, and pesticides over large land areas. It also involved biodiversity loss due to land transformation and fragmentation. High animal-based foods lead to significant land encroachment and transformation despite increased sustainable practices.
The continual increase in the demand for meat production enhances the risk of future zoonoses. Similarly, aquaculture is growing rapidly due to a steady decline in wild aquatic food sources. Aquaculture intensification also increases the risk of zoonotic spillovers.
The agroecological animal-based scenario was linked to excessive livestock production via intensive silvopastoral systems, mixed cropping systems, and regenerative agriculture.
The broadscale land use and animal husbandry increase the risk of zoonotic spillover events. Agroecological methods associated with high agrobiodiversity and low inputs could reduce the spillover risks linked to the use of water, antibiotics, pesticides, and biodiversity loss.
The industrial and agroecological plant-based scenarios could restore the natural ecosystem via smaller ecotones, decreased agricultural areas, and higher biodiversity. These food systems pose a lower risk of zoonotic spillovers. Wildlife hunting practices entail higher zoonotic spillover risks.
Future outlook
The current study underscores the factors that increase the risks of zoonotic spillovers. It also highlights how these risks could be alleviated. In the future, more follow-up empirical research could quantify these conceptual insights.
Since many low-income and middle-income countries obtain their nutrition from animal-based foods, a total replacement of the animal food industry with a plant-based food system is not possible. Targeted policies must be formulated for wildlife harvesting. In addition, the underlying spillover mechanisms must be analyzed.
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