Toward a healthy planet: Implementing a One Health approach to conservation

To address health challenges equitably and sustainably, it is necessary to understand that every form of environmental degradation may have direct or indirect negative consequences for human and animal health that can be prevented or mitigated with a One Health approach. However, the importance of the environmental pillar of One Health is the least well understood and prioritized in One Health strategies and conventional medicine.

Strengthening the voice of the environmental sector in One Health interventions is vital. But in order to do so, we need a holistic understanding of the relevance of the environment in One Health. The environment is critical to overall human health, influencing it in myriad ways that can be summarized as follows:

• Ecosystem services: Healthy ecosystems provide essential services like clean air, water filtration, and erosion prevention, which are vital for human and animal health. Environmental health ensures that the shared environment and services it provides remain safe and sustainable for all.
• Pathogen transmission: The majority of infectious diseases can be spread through interactions between humans, animals, and the environment. For example, zoonotic diseases like Ebola and COVID-19 can jump from animals to humans due to environmental factors that bring them into closer contact. A healthy environment reduces the likelihood and spread of diseases and contributes to the well-being of all living beings. Intact landscapes provide animals with the habitat they require to maintain distinct populations and limit the ability of infectious diseases to spread among and between species. Habitat loss and degradation concentrate animal populations, leading to the emergence of novel infectious diseases that can have dramatic impacts on people and society.
• Pollution and contamination: Environmental pollutants such as pesticides, plastics, and industrial waste can pose significant health risks to humans and animals. Contaminated water or food can lead to outbreaks of diseases. Environmental health safeguards the quality of water and food sources upon which humans and animals rely.
• Innovations from nature: The environment plays a pivotal role in the development of new medicines, therapies, and sustainable technologies that promote resilience, adaptation, and transformative solutions benefiting human and ecological systems.
• Climate change: Environmental health can address some of the health impacts of climate change, such as heat-related illnesses, increased prevalence of vector-borne diseases, and food insecurity. These impacts affect human health directly and can also influence animals and ecosystems.

The relationship between environmental, animal, and human health is complex. Developing an effective, integrated approach to addressing the underlying challenges requires a wide range of strategies and interventions.

To achieve healthy ecosystems, people, and animals, WWF has developed guidance on six strategic areas:

Ensuring “landscape immunity” means safeguarding sustainable and healthy ecosystems in which animal–pathogen–human interactions are in balance and neither wildlife nor humans are overly stressed or forced to aggregate or migrate because of land use-induced changes.

Land-use change that deforests, converts, and fragments natural habitat can force wildlife into closer proximity to humans and livestock. Stressed wildlife are also more vulnerable to infection, and more likely to either “shed” and introduce pathogens to people or livestock or, in turn, be susceptible to catching pathogens from people or livestock. Natural predators and scavengers can be sensitive to these changes and are more likely to be replaced in an unhealthy landscape by species known to host pathogens, like rodents.

Deforestation, conversion, and fragmentation are widely linked to infectious disease dynamics, and many land-use changes play a role, including infrastructure development (such as roads, rail, dams, and mining), coastal zone degradation, wetland modification, and urbanization.

Wildlife trade intensifies human-animal contact through various activities along trade routes, such as during farming, hunting, butchering, storage, and transport, as well as at live wildlife exhibits, markets, and restaurants. These direct interactions increase the risk of spillover of zoonotic diseases. Wildlife trade involves an estimated one-quarter of all mammal species, including high percentages of bats, rodents, and primates, which are known to be high-risk species that can host a high diversity of zoonotic pathogens. Illegal wildlife trade also circumvents all regulatory controls, veterinary checks, and appropriate care and facilities for live wildlife, increasing the potential for zoonotic disease transmission.

Preventive medicine is the practice of promoting veterinary and medical activities that support the health and well-being of an individual or population to prevent disease spread, disability, and death. This includes vaccination, parasite prevention and control, and health screening, as well as strategies for appropriate management of existing diseases and related complications.

Preventive medicine is crucial for people and livestock. While it is used less commonly for wildlife, it plays a critical role in certain scenarios, such as vaccinations of endangered black-footed ferrets against sylvatic plague.

Zoonotic pathogens can emerge at any time, threatening every society’s health, well-being, and economy. A One Health intelligence framework that collects and shares epidemiological data and information across a broad range of sectors can aid early detection of pathogens and enable early warning of emerging threats. This can allow for early intervention to respond to outbreaks, ultimately reducing the impact of disease.

Monitoring can improve our understanding of existing host and pathogen dynamics, drivers of disease, and disease transmission in animals and humans in their shared environment. Monitoring the origin, spread, and patterns of new pathogens in geographical regions and interfaces can form part of a surveillance strategy that can potentially anticipate and prevent pandemics.

Livestock plays a major role in global food systems and contributes to poverty reduction, food security, and agricultural development. Livestock farming is also often the predominant form of land use within natural grasslands and savannahs. These systems are usually where the One Health triad of people, the environment, and animals are most intertwined, with herders, livestock, and wildlife all living together and sharing resources from the same ecosystem.

Unsustainable livestock management can negatively impact wildlife while increasing the potential for transmission of diseases among humans, wildlife, and domestic animals.

Effective One Health strategies for sustainable livestock management, including herd health management, sustainable rangeland management, and managing the interface between livestock and wildlife have the potential to improve human health, increase livestock productivity, and deliver equitable benefits to people, particularly in low and middle-income countries.

To achieve the changes needed to ensure healthy people, animals, and ecosystems, behavior change and education will be essential tools for a coordinated and cross-sectoral One Health approach. Behavior change efforts that could be crucial to One Health initiatives encompass a wide variety of tactics, from reducing demand for wildlife products with a high-risk potential for disease to behaviors around hygiene, food safety, and waste management practices.