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One health: seeing the whole ecosystem

With One Health gaining increasing prominence in research and the media, we look at the driving factors behind the concept and ask what action may need to be taken.

The philosophy at the heart of “One Health” is far from new but it has acquired a fresh impetus as the fallout from the COVID-19 pandemic continues to be picked over. Was it triggered by an animal virus crossing over to humans?

Could better food safety have prevented its spread? Did environmental destruction make it more likely? As critical as these lines of inquiry are individually, the greater significance, when viewed from the perspective of One Health, is that they cannot be separated from one another.

As a concept, One Health has its roots in the 1960s, when Calvin Schwabe, a veterinarian and public health expert, wrote about the close relationship between human and animal medicine. Leading on from this observation, the concept suggested that human medicine, particularly in relation to public health, doesn’t occur in isolation, and that not only does the interaction between humans and animals need to be taken into account, but also the interaction between humans and animals and the environment.

This holistic view of medicine began to take a firmer shape during the first decade of the 21st century, with the emergence of new and threatening infectious diseases, such as H5N1 influenza (bird flu), severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The origins of these of outbreaks could be traced to the breakdown of the traditional barriers between animals and humans, allowing the virus to jump from one to the other.

Big steps

These events were the impetus to establish a formal approach for One Health. A big step came in 2008 with the launch of the One Health Framework, known as the FAO-OIE-WHO Collaboration, by the Food and Agricultural Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE) and the World Health Organization. This set out a vision of “a world capable of preventing, detecting, containing, eliminating, and responding to animal and public health risks attributable to zoonoses and animal diseases with an impact on food security through multi-sectoral cooperation and strong partnerships”.

Then in 2009 the One Health Commission was set up. The objective of this joint initiative by the American Medical Association, American Veterinary Medical Association and American Public Health Association was to bring experts together from across all three disciplines and to “raise awareness and to educate all audiences about the importance of transcending institutional and disciplinary boundaries to transform the way that human, animal, plant, and ecosystem health professionals work together for the health of all living things and the planet”.

In the years that followed, more organisations dedicated to understanding and promoting the tenets of One Health were established, international cross-discipline conferences were held, research papers written and strategies drawn up. Ultimately none of this did much to help prevent the emergence or soften the impact of the SARS-CoV-2 virus and the global pandemic; even so, one of the lessons coming out of the pandemic has been an evident need to sharpen the focus on a coherent and more intent response to the underlying issues.

“Perhaps it has generated more interest in the wider world outside of nerdy microbiologists like me”

 

The SARS-CoV-2 virus

“The emergence of the SARS-CoV-2 virus that causes COVID-19 has underlined the need to strengthen the One Health approach, with a greater emphasis on connections to animal health and the environment,” says WHO. “Attempting to save money by neglecting environmental protection, emergency preparedness, health systems, water and sanitation infrastructure, and social safety nets has proven to be a false economy, and the bill is now being paid many times over.”

 

“Resistant bacteria can be transmitted between companion animals, such as dogs, and their owners”

Today, WHO’s definition of One Health emphasises vigorous action, describing it as: “an approach to designing and implementing programmes, policies, legislation and research in which multiple sectors work together to achieve better public health outcomes”. The areas where it believes a One Health approach is especially relevant include food safety, zoonotic diseases, climate change, environmental health and antimicrobial resistance.

Here in the UK, a proponent of the One Health approach is Dr Sarah Pitt, Principal Lecturer in the School of Applied Sciences at the University of Brighton. She says a key step is to remove some of the barriers between human and animal medicine: “They’re taught separately, you are either a vet or a doctor, and they don’t necessarily talk to each other. But there’s a lot of overlap in learning and understanding anatomy and physiology, particularly for mammals. What we learn from or know about one thing we can extrapolate to another. It doesn’t always translate but it’s often a very useful starting point.”

In essence it’s about not looking at things in isolation. But it’s about taking that step further and taking a much wider view. “One Health sees the whole ecosystem, which includes humans and animals, but also includes the climate, and the environments we live in, whether that’s a city or a village. These things are all part of our health,” says Sarah.

Major concerns

Climate change and its associated extreme weather events in particular have in recent years rammed home this point. “On the one hand people might be worried about mosquitoes appearing in Surrey, but on the other there is a lot more to it than that. We have to ask, with the very hot temperatures and the extreme flooding we had all across the world last year, how does that affect people’s health and wellbeing? It leaves them susceptible to all sorts of diseases, and if gets too extreme they are likely to want to migrate somewhere not quite as hot, and they might be carrying those infectious diseases with them. If they decide to stay where they are, they will have to live in a much more restricted environment, so how would that affect their health?”

Another complicating factor is deforestation, which has only accelerated over the past couple of decades, bringing humans and animals into much closer contact in ways that previously never occurred. The potential ramifications of this for global health could be enormous.

Along with COVID, has all this had the effect of raising awareness of One Health and the many intertwined issues? “Perhaps it has generated more interest in the wider world outside of nerdy microbiologists like me,” says Sarah. “That has got to be a good thing, hasn’t it?”

A further key concern under the One Health banner is the well-documented problem of antimicrobial resistance. With the misuse and overuse of antibiotics among humans and animal populations throughout the late 20th and early 21st centuries, the rise of drug-resistant microbes is now one of the major challenges facing medical science.

In a recent paper, “One Health interprofessional stewardship to combat antimicrobial resistance”, published in Nature Medicine, a research team at Tufts University in Massachusetts found that the threat of resistance is not limited to animals in agriculture: “studies increasingly recognise that resistant bacteria can be transmitted between companion animals, such as dogs and cats, and their human owners, and that pets can act as a reservoir for multidrug-resistant organisms that affect human health”.

As with COVID-19, the issues are far closer to home than suspected.


A British Journal of Biomedical Science special edition

Acknowledging the growing importance and awareness in the wake of the COVID-19 pandemic of the need for a balanced and sustainable approach to the health of humans, animals and ecosystems, the integrated approach of One Health will be the subject of a special edition of the British Journal of Biomedical Science later this year.

Manuscript submissions are being welcomed on perspectives, challenges and recent advances in the fields of One Health, diagnostics, pathology and epidemiology of existing and emerging zoonotic diseases. The deadline date for submission is 17 April 2023.

For more details visit: frontierspartnerships.org/research-topics/34/zoonoses-and-one-health

 


Antimicrobial stewardship

One of the authors, Dr Claire Fellman, Assistant Professor in the School of Veterinary Medicine at Tufts, says that the One Health approach underpins much of the school’s work. “It’s a really important concept for us. There’s a lot of expertise on the human side of medicine for which we need to build analogous expertise on the veterinary side. The exciting thing is that it’s not just them helping us. On occasions we’ve been able to help them with health issues related to zoonosis.”

Whether they are in the doctor’s office or the veterinarian’s office, notes Claire, people are becoming more receptive to the message that antimicrobials need to be protected and preserved. “Of course One Health applies much more broadly,” she says, “but I do think antimicrobial stewardship is a good example of how it can work.” The job is far from finished, though: “We still need to gain traction within the medical fields of the concrete benefits and I also think we’ve been a little slow to loop in the environmental aspects.”

She adds that, from a US perspective at least, there is now a firm expectation of collaborative science. “I think that within 10 years collaboration is going to be extensive. And as we realise the interconnections and the expertise that could be found, even more collaboration will be expected, and even greater benefits will be realised.”

As the issues that feed into One Health become yet more pressing, raising uncomfortable questions about the robustness of global health, strenuous and systematic collaboration might appear to be the best bet for avoiding the next pandemic and similar devastating events.

Image credit | Sam-Falconer

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