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One Health: an all-encompassing strategy for better well-being

Understanding the deep connections among human, animal and environmental health is more important than ever, according to the two heads of a groundbreaking EU research project.
Hein Imberechts (left) and Arnaud Callegari led the One Health European Joint Programme. © One Health EJP

In an era of interconnected global threats, the “One Health” idea recognises that human well-being is tightly tied to that of animals, plants and the wider environment.

For example, close links exist among human food, animal feed and nature, with the state of any one of them affecting the others. 

The EU is playing a leading role in the move towards a fairer, healthier and more resilient food system. The goals include environmental sustainability, animal welfare and the reduction of antimicrobial use, with One Health at the heart of the transition.

A landmark partnership with public authorities across Europe called the One Health European Joint Programme, or EJP, has helped to chart the course. The project, which ended in September 2023 after five years, tackled the rise in animal-borne diseases, the overuse of antibiotics and emerging threats.

Horizon Magazine spoke to Dr Hein Imberechts, a scientific advisor at Belgian health institute Sciensano, and Arnaud Callegari, programme coordinator at the French Agency for Food, Environmental and Occupational Health and Safety, about the lessons learned. Imberechts and Callegari jointly led the One Health EJP.

1. How is the Covid-19 pandemic relevant to One Health?

Hein Imberechts (HI) - Covid-19 is not the first human disease to be attributed to spill-over from animals and it won’t be the last. However, what it did more than any previous outbreak is bring those links to the attention of decision-makers and into the public eye. 

The importance of the origin of SARS-CoV-2, the way it spread through human populations and the possibility of spread back into animals highlighted these links. 

Early in the pandemic, the One Health EJP set up a specific project – COVRIN – to reinforce Europe-wide collaboration and integrate research and risk assessment activities on SARS-CoV-2 across public and animal health institutes. 

2. How does the environment affect animal-to-human diseases? 

Environmental changes caused by human activities are having a significant impact on infections in animals.

Dr Hein Imberechts, One Health EJP

HI - The majority of new and emerging human infectious diseases are thought to come from animals. Environmental changes caused by human activities are having a significant impact on infections in animals and, therefore, the risk of these pathogens spilling over into humans. 

This can be through local impacts such as habitat loss and increased contact between humans and animals, for example through the wildlife trade. What is perhaps more difficult to measure – and a longer-term threat – is the effect of climate change on how these infections are spread. 

We are only just starting to understand, for example, the potential impact of changes in the geographic range of disease-bearing organisms – vectors – such as ticks and mosquitoes.

3. What role do animals play in disease transmission?

HI - Animals play a significant role in the transmission of infectious diseases to humans. But diseases can also be spread from humans to animals – reverse zoonoses. For example, it happened with the Covid-19 virus where minks and pets were infected through their contact with infected people.

It is a complex web of connections. The environment itself can become contaminated with pathogens, which can then infect other animals and indeed humans. Animals can harbour smaller organisms such as ticks, mites and so on that then facilitate the transmission of pathogens to different species.

A big concern here is the growth of antimicrobial resistance – the resistance of pathogens to common treatments and antibiotics. This too can be spread between animals and humans, rendering existing treatments ineffective. 

4. How could better animal welfare also improve human health?

HI - The welfare of food-producing animals depends on how they are kept and how they are handled during transport and at the slaughterhouse. If this is done in the most appropriate way, the animals are less stressed, less likely to get sick and less likely to become infected with and shed pathogens. 

Better overall health of animals means less need to treat them with antibiotics. This benefits not only the animals themselves but all of us because it will result in fewer antibiotic-resistant pathogens, which is important for humans too.

5. What is the link between antimicrobial resistance and animal and environmental health?

Arnaud Callegari (AC) - Antimicrobial resistant organisms are found everywhere – in humans, animals, food, feeds, plants, water, soil and air. They can spread from person to person, or from animals to people, or from food of animal origin, or even just from the environment they – or indeed we – live in.

The main drivers of antimicrobial resistance include the over- and misuse of antibiotics in humans and animals – but less well-known are changes in the way we are using land and the pollution of soil and water with residues from agricultural herbicides and insecticides.

For example, evidence suggests that faecal pollution is higher in urban than agricultural areas and contributes to antimicrobial resistance and that chemical biocides contribute to bacterial resistance.

6. What were the main achievements of the One Health EJP?

We have built a whole community of One Health researchers – not just for today but also for the future.

Dr Arnaud Callegari, One Health EJP

AC - The One Health EJP brought together more than 500 researchers in 44 organisations over 22 European countries. All these organisations are now better prepared to work together to face future disease outbreaks as well as the growing threat of antimicrobial resistance. 

We have built a whole community of One Health researchers – not just for today but also for the future. 

We have also generated a wealth of new knowledge that is now accessible for everyone interested in food safety, infectious diseases and antimicrobial resistance – whether national authorities, European and international agencies or even the private sector and non-governmental organisations. 

7. What were the main lessons learned and challenges faced?

AC – The scale of the One Health EJP meant that people had to learn to work together not only across different countries but also across different disciplines – human health, veterinary medicine, agriculture and food production, environmental protection and so on. 

The challenge now will be to make sure that the knowledge generated by the EJP is communicated to those who need it and is turned into action that will make a difference. This communication work will be taken up by the Med-Vet-Net Association, the original instigators of the EJP.

8. How will the European Partnership on Animal Health and Welfare help?

AC – It will focus more specifically on the sustainable production of food-producing animals and aquaculture. Its aim is to ensure a high level of health and welfare at every stage of an animal’s life. This, in turn, will help prevent and control disease in these animals and reduce the use of antibiotics. 

Much attention will be paid to improving disease and welfare monitoring systems as well as conditions for animals during transport and slaughter. The development of new vaccines and treatments is also foreseen. 

9. What are the main policy and political challenges ahead?

AC - One Health has become a familiar term on the political agenda. Health policies are now much more aware of the environment-animal-human axis of disease transmission. 

Putting these concepts into action on a wide scale remains a challenge, however. A proper legal framework and financial resources for One Health actions are still needed. 

The next step will be to broaden the scope of the One Health approach to food safety by adding new areas of research such as chemical contaminants. 

Publication of this article coincides with a European Commission conference on “One Health for All, All for One Health” in Luxembourg on 13 November 2023.

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