One Health: Using a holistic approach to combat global disease and improve population health

To support population health at a global scale, a collaborative, transdisciplinary approach is vital. With recent outbreaks like COVID-19 and Ebola, the awareness of zoonotic diseases—those that jump from animals to humans—continues to grow. One Health can help stakeholders better understand and prevent future pandemics.

What is One Health?

One Health is a multi-sector approach that recognizes the interconnection between people, animals, and our shared environment. One Health employs a holistic perspective to better understand and solve public health threats on a local, regional, national, and global scale. By encouraging collaboration between sectors otherwise siloed, this approach can more effectively achieve comprehensive and integrated public health outcomes.

A history of One Health

The term One Health dates to 2006, but the concept of One Health and the natural world’s interconnectedness with human health goes back to ancient times. One Health is grounded in traditional wisdom and is a strong theme among many Indigenous tribes, but it is the rapid environmental change of the 21st century that brings it to the forefront of public health.

Major components of One Health

All three components—human, animal, and environmental health—are closely intertwined. Details of each component are provided below:

Human health: The physical, mental, and social wellbeing of humans relies on several factors, including location, medical access, and environment. Within the One Health concept, human health can be affected by close proximity to wild or domestic animals and the larger environment.

Animal health: Encompassing wild animals, domestic animals, and livestock, animal health plays a key role in the shared environment. The One Health approach takes into account the potential spread of animal-borne diseases or possible spillover effects from these animals and their environments.

Environmental health: This includes water, soil, air, plants, and ecosystems. Relevant sectors include agriculture, climate, and environmental sciences. Systems-level shifts that the One Health approach takes into account may include deforestation, changes in land use, or the spread of non-native plant species.

Climate change, pollution, migration, and human behavior continue to impact animal and environmental ecosystems, increasing the urgent need for data-driven responses to public health threats. A transdisciplinary approach, One Health relies upon the collaboration of professionals across different sectors—including public health, agriculture, environment, and wildlife management—at the local, regional, national, and global levels to achieve optimal health outcomes.

How does a One Health approach work?

One Health works by bridging the gap between human, animal, and environmental health by engaging experts across the sectors. In practice, this requires:

• Systemic thinking
• Holistic planning
• Transdisciplinary working

To employ a successful One Health approach, public health leaders must develop and implement surveillance and reporting infrastructure to capture epidemiologic data. For example, a country can bring together disease surveillance by human, animal, and environmental health departments, resulting in evidence-based datasets that help shape response strategy options for public health threats. By encouraging the sharing of data and responsibility among key stakeholders, networks of expertise can facilitate innovative solutions at a global scale.

Surveillance systems drive collaborative response

Surveillance systems are critical to detecting and reporting cases of zoonotic diseases in a timely manner to drive collaborative solutions. To create more effective evidence-based health interventions, One Health surveillance systems collect, validate, analyze, interpret, and disseminate information collected on all three sectors.

Along with a consortium of partners, we implement the U.S. Agency for International Development-funded IDDS (Infection Disease Detection and Surveillance) project. This project strengthens public health diagnostic networks and surveillance systems to effectively detect and monitor infectious diseases of public health importance in more than 20 countries in Africa and Asia. Since May 2018, we have had a major impact in those countries by improving diagnostics and surveillance. IDDS is doing its part to bridge the gap between animal and human health systems in 10 countries in Africa and Asia, with a focus on training and helping veterinary laboratories follow international standards for diagnostic testing quality, safety, and efficiency. In 2021, IDDS was key to the development of Uganda’s National Strategy for Coordinated Surveillance of Priority Zoonotic Diseases. The strategy provides practical guidance on data sharing and joint disease outbreak response in Uganda. Read the IDDS 2021 annual report to learn more about the project’s impact.

A critical moment for an interdisciplinary approach

A clear example of the direct linkage between animal, human, and environmental health systems, the COVID-19 pandemic reinforces the immediate need for a One Health approach. The most disruptive pandemic in modern history, understanding this zoonotic disease requires multidisciplinary collaboration.

Applying a One Health lens in responding to the COVID-19 pandemic reinforces key areas such as:

• More integrated surveillance infrastructure and monitoring of infectious diseases in both humans and animals
• Improved collaboration between stakeholders
• Awareness of effective institutional landscapes and regulation of transmission hotspots
• Need for equitable solutions for disproportionate disease burdens on vulnerable populations

According to the World Health Organization, zoonoses are on the rise. In fact, 70% of all current and re-emerging pathogens are zoonotic. To prevent and contain COVID-19 and other zoonotic diseases, developing a comprehensive One Health approach is critical.

Zoonoses—prevalence and risks

The prevalence of zoonotic diseases extends well beyond the current COVID-19 pandemic. Other recent zoonoses of significance include:

• Ebola
• Avian Influenza (bird flu)
• Nipah Virus
• Severe Acute Respiratory Syndrome (SARS)
• Middle East Respiratory Syndrome (MERS)

Zoonotic diseases are common, spreading through a variety of sources, including direct and indirect animal contact, food- and waterborne contamination, and vector-borne illness. The CDC estimates that six out of every 10 known infectious diseases can spread from animals—and their impact results in many consequences, ranging from mild illness to death.

The Global Health Security Index measures and tracks 195 countries’ risk and vulnerability to disease outbreaks, including zoonotic disease.

Current issues related to One Health

Antimicrobial resistance (AMR) is a major global health concern that threatens the effectiveness of treatment for infections including zoonoses and other diseases. AMR—which includes resistance to antibiotics, antivirals, antifungals, and antiparasitics—spreads through the food chain and the environment. To prevent infections and continued resistance, a One Health approach that incorporates agriculture, food, and environmental disciplines is crucial to curtailing related morbidity and mortality. The IDDS project works to improve testing capacity for AMR in veterinary laboratories in Cameroon, Guinea, Kenya, Senegal and Tanzania.

Global Health Security Agenda

The Global Health Security Agenda (GHSA) is a collective, global effort to strengthen countries’ capacity to prevent, detect, respond to, and protect against emerging and re-emerging infectious disease threats such as viruses and bacteria. By engaging with multisectoral partners across the globe, the GHSA accelerates capacity-building efforts to meet the core requirements of the International Health Regulations (IHR).

To facilitate progress towards these health security goals and support the implementation framework, the GHSA developed a set of Action Packages that focus on global activities, highlight measurable approaches, and define specific commitments at the country level with five-year targets. These Action Packages include the following key areas:

• Identifying priority pathogens and combating AMR
• Emphasizing a One Health approach to control zoonotic disease threats
• Implementing a strategic plan for biosafety and biosecurity
• Establishing and maintaining an effective outbreak response plan
• Strengthening national laboratory systems and effect point-of-care diagnostics;
• Initiating event-based surveillance systems and effective communication and collaboration across sectors
• Ensuring timely and accurate disease reporting to WHO
• Prioritizing workforce development and training the next generation of health workers
• Establishing emergency operations centers capable of responding to public health emergencies

These key areas ensure that countries are prepared to respond to public health threats. The application of a One Health approach ensures that all pathogens affecting human, animal, and environmental health are considered in supporting the goals and objectives of the GHSA.