Protecting human health through landscape immunity

When humans alter the natural landscape, it increases the risk of zoonotic spillover, which is when a disease jumps from wildlife to humans. Disease spillover can be dangerous because it introduces novel illnesses that may be difficult to control or treat in human populations.

These disease spillover events can occur when land use changes since it forces wildlife into closer proximity to humans, introduces stress that leaves wildlife more vulnerable to infection and changes the distribution of pathogens across the environment. Given the risk associated with zoonotic spillover, it is essential to the protection of human health to formulate land conservation policies to reduce the risk of disease spillover. 

A team of researchers, including CEID’s Daniel Becker, sought to aid this effort through the presentation of land use-induced spillover. The concept of land use-induced spillover can help policymakers understand why changes in land use can lead to novel disease emergence as well as how to provide protection from disease through the preservation of healthy landscapes.

Land use-induced spillover relies on two components: landscape immunity and dynamics of proximity. Landscape immunity is a set of ideal ecological conditions that allow wildlife to avoid getting sick, which in turn preserves human health. Dynamics of proximity are the ways disease transmission is facilitated, including the pathways, degree, and frequency of contact between humans and wildlife.  

Achieving landscape immunity and limiting dynamics of proximity lowers the risk for pathogen spillover substantially. In order to meet these goals, it is necessary to make changes to the formulation of conservation policies that foster the attainment of landscape immunity. The authors suggest four primary standards to be integrated into the development of conservation policy. 

The first is the recognition that humans influence and are influenced by ecological systems. Some conservation policy fails to recognize the impact humans have on certain ecological systems and the influence these systems have on humans. By recognizing the role of humans in ecological systems, policymakers can mend the disconnect many people feel from the environment and encourage more thoughtful treatment of natural landscapes. 

The second standard is recognizing that protecting human health is an ecosystem service. This refers to the health benefits the preservation of the natural environment offers to humans. Things such as access to clean drinking water, food and countless other services are provided by nature. However, most policies and governmental organizations fail to recognize the protection of human health as an ecosystem service. Recognizing the role nature plays in human health can open the door for human health impact to be included in environmental impact reports, which can raise awareness of when a land-use change project could risk a spillover event.

The third standard suggests a focus on investment in prevention measures rather than waiting and spending more money on the fallout when a spillover event inevitably occurs. This includes striving for landscape immunity, which can be achieved through sustainability initiatives and land conservation policies. 

The fourth and final standard to promote within the development of conservation policy is to utilize ecological restoration. In order to achieve landscape immunity, it is necessary to restore existing landscapes. For example, tree-planting initiatives can be used to prevent zoonotic events by altering the dynamics of proximity and lessening the stress on wildlife that can weaken their immune systems.

These four suggested tenets for conservation policy will help to safeguard humans as well as preserve the environment for wildlife. Understanding how to achieve landscape immunity and control dynamics of proximity is of paramount importance to preventing zoonotic spillover events.

To read more about this research, click here.

By Amanda Budd