There are various definitions of One Health, but they converge on the idea that One health is a collaborative, multisectoral approach that aims to achieve optimum health for people, animals and the environment, through recognising the connections and health risks they share. Infectious disease emergence and preventing epidemics is a common focus of One Health research and practice, given that 75% of recently emerging infectious diseases in humans are zoonotic. Beyond zoonoses, One Health more broadly emphasises the importance of relationships between humans and animals for their mutual health and wellbeing, such as the effects of the relationship between people and their companion animals on mental health. One Health also places intrinsic value on animal health as its own good, not only through its relevance to human health.
In practice, the environment component of One Health is often overlooked, with a much greater focus on shared health risks affecting humans and animals. In contrast, Ecohealth is a field that focuses on the role of human-ecosystem interactions, including ‘ecosystem services’, on health. Ecohealth emphasises biodiversity as a core value that has intrinsic worth independent of any benefits or harms to people, but the majority of research and practice is focused on human health. Ecohealth enshrines the value of indigenous and other forms of knowing alongside ‘scientific’ knowledge.
Planetary Health is a recently coined phrase to draw together and initiate research on “the health of human civilisation and the state of the natural systems on which it depends” (1). The challenge for this emerging field is to develop concepts and measures of the health and sustainability of current and future human civilisations. As such, this approach is focused on humans, but recognises that animal and ecosystem health are essential to its goals.
Here at Ausvet, we see One Health as an approach that recognises the close relationship between people, animals and the environment, and the impact that poor health in one of these areas can have on the others. A One Health approach is vital for the prevention and control of zoonotic diseases, but is also important in understanding a wide range of challenges such as antimicrobial resistance, food security and nutrition, and community and mental health issues arising from relationships with land and the environment in the face of environmental degradation and climate change.
For example, though African Swine Fever (ASF) is not a zoonosis, the global ASF pandemic poses a substantial threat to global food security and nutrition, particularly in resource-limited settings where pork is a key protein source. Similarly, crop pests and diseases are responsible for 50% of crop losses on the African continent. This has myriad flow-on effects on human health, with direct impacts on nutrition, but also indirect impacts including families’ ability to pay for health care, and the adverse effects of high levels of pesticide use on reproductive health.
Our expansive view of One Health is partly shaped by the fact that we are epidemiologists. Our basic epidemiological training equips us to apply a variety of methods for understanding patterns of health in any population. Nonetheless, a sharp divide between public health and veterinary epidemiology practice remains, and lack of collaboration across sectors is consistently recognised as the biggest challenge to implementing One Health effectively5. This is not surprising; in most public health-oriented epidemiology training programs; students might learn the basics of topics as diverse as infectious disease modelling, molecular epidemiology, and life course approaches, but not the basics of transmission of influenza virus in humans, domestic poultry and wildlife. This is despite the fact that there are far more similarities in the epidemiological methods for infectious diseases of humans, animals and plants (such as outbreak investigation, spatial analysis, and modelling) than compared to, for example, pharmacoepidemiology.
This is starting to change. There are a growing number of academic and field-based epidemiology training programs around the world that are incorporating One Health. For example, the London School of Hygiene and Tropical Medicine and the Royal Veterinary College now offer a joint MSc in One Health, and TEPHINET is developing One Health content for field epidemiology training programs (FETPs), and there are collaborative efforts to develop field epidemiology training for veterinarians around the world.
For those who have already completed their training, the career pathways into One Health are less clear. Imposing a top-down One Health framework on existing national public and animal health services that have not already embraced it, is difficult and rarely productive. Ausvet has found that a bottom-up approach is much more effective – start with information, in the form of an integrated health information system, that provides access to human, animal and environmental health data, and then demonstrate how our understanding of problems and solutions can be enhanced by integrated epidemiological analysis of information from different domains.
2 Harrison, Sarah, et al. “EcoHealth and One Health: A theory-focused review in response to calls for convergence.” Environment international 132 (2019): 105058.
3 Davis, Meghan F., et al. “Checklist for one health epidemiological reporting of evidence (COHERE).” One Health 4 (2017): 14-21.
4 Lebov, J., et al. “A framework for One Health research.” One Health 3 (2017): 44-50.
5 Destoumieux-Garzón, Delphine, et al. “The one health concept: 10 years old and a long road ahead.” Frontiers in veterinary science 5 (2018): 14.