When we consider the concept of health, our understanding often changes based on our perception: A doctor would think of human health, a veterinarian of animal health and a conservationist of environmental health.
One Health is a concept and approach that attempts to link all of these areas. It recognises that humans do not exist in isolation, but are a part of a larger whole, a living ecosystem, and that activities of each ecosystem member affect the others.
One Health is the collaborative effort of multiple health science professions, together with their related disciplines and institutions – working locally, nationally and globally – to attain optimal health for people, domestic animals, wildlife, plants, and our environment. [i]
One Health’s evolution
One Health is a relatively new term, although the thinking behind it is not. Its global prominence has been gorwing in the past decade. For example, in 2007 representatives of 111 countries and 29 international organisations met for the International Ministerial Conference on Avian and Pandemic Influenza. During this meeting, governments were encouraged to further develop the One Health concept by building linkages between human and animal health systems for pandemic preparedness and human security.
In 2009 a One Health Office was established at The Centers for Disease Control (CDC). The CDC now uses a One Health approach by working with physicians, ecologists and veterinarians to monitor and control public health threats. Their focus is on learning about how diseases spread among people, animals and the environment.[ii]
In 2011 the first International One Health Congress was held in Australia. Delegates from 60 countries and a range of disciplines came togther to discuss the benefits of working together to promote a One Health approach. In addition to understanding the interdependence of human, animal and environmental health, attendees agreed that it was important to include other disciplines such as economics, social behaviour and food security and safety.
Understanding Biodiversity
Biological diversity – or biodiversity – is the term given to the variety of life on Earth. With human population growth increasing around 90 million per year since the last century, there have been huge related effects on landscape change, agriculture practices and environment. The related decline of biodiversity – specifically plant and animal extinction – is a global issue with wide ranging implications for human and planetary survival.
Biodiversity provides us with many “ecosystem services” that can’t otherwise be engineered. Natural ecosystems clean the air, filter water, suck greenhouse gases from the atmosphere, provide genetic stock for agriculture, contribute chemicals that cure cancer. Biodiversity can also protect human health by reducing the probability of human exposure to disease agents transmitted from wildlife.
Human-induced environmental changes, such as habitat fragmentation, can inadvertently increase disease risk by reducing both predators and biodiversity. Lyme disease, for example, is spread by ticks. Possums and squirrels can eat these ticks without harm, but deforestation means less of these species due to loss of their habitat. A more diverse community of mammals and birds, and more habitats, essentially means fewer infected ticks crawling around in the woods.[iii]
One Health and Biodiversity
While declines in biodiversity are alarming in their own right, they also represent a significant public health threat to human populations who depend on these animal resources for nutrition. Of all public health risk factors, malnutrition is the single largest contributor to the global burden of disease — accounting for one-third of the entire burden of disease in poor countries.[iv]
An additional concern relates to zoonosis – a process by which disease travels from animals to humans. Examples of zoonses include West Nile virus, the Bubonic Plague and Salmonella. A theory is that most human disease originated over centuries from the domestication of wild animals. In tropical climates, where biodiversity is high (thus is a rich source of pathogens), there is a waiting potential danger of new diseases once those areas are opened up due to deforestation and population growth.[v]
The World Health Organisation (WHO) has also identified antimicrobial resistance (AMR) as one of the key health global issues facing our generation. The risk of treatment failure in animals and humans attributable to AMR arising from the use of antimicrobial agents in food-producing animals or companion animals is a serious concern. AMR is a bidirectional zoonosis, with links to other environmental areas like aquaculture, food plants and drinking water. The ease with which AMR genetic material can be transferred between organisms means we are all ‘swimming in the same gene pool’ and all sources of AMR organisms need to be taken seriously. [vi]
The future
Much of the work of a One Health approach still lies in research and also efforts to get the identified multiple disciplines truly working together, particularly in an institutional context.
The One Health approach encapsulates the concept and thinking of Healthy Parks, Healthy People. While the driver behind One Health is largely improved human health, the related potential benefits to environmental and animal health are huge.
[i] Source: https://www.onehealthcommission.org/en/why_one_health/
[ii] Source: http://www.cdc.gov/onehealth/
[iii] Source: http://www.caryinstitute.org/newsroom/biodiversity-and-human-health-why-more-species-mean-fewer-cases-lyme-disease
[iv] Source: http://www.wcs-heal.org/approach/module-1-executive-summary#conduct
[v] Source: http://www.nature.com/nature/journal/v447/n7142/abs/nature05775.html
Image source: http://www.nature.com/nature/journal/v447/n7142/fig_tab/nature05775_F1.html