The One Health Model
Veterinary organisations and practitioners around the world have been proponents of the One Health model for many years. It combines human, animals and environmental aspects to address global health challenges. This approach has spread to human medicine in more recent years, and is particularly relevant in combating zoonotic diseases.
A disease is called zoonotic when it can move between animals and humans. While some diseases, like toxoplasmosis, can be very mild, others, like rabies, can be extremely dangerous. Although the exact origin of COVID-19 is still unknown, in recent months zoonoses have moved into the public spotlight after scientists discovered that the virus is extremely closely related to one found in horseshoe bats. Zoonotic diseases are one of the biggest threats to human health across the world. Studies of emerging diseases suggest that up to 75% of new diseases could come from animals. As habitat degradation and environmental exploitation increase, potentially so does the risk of novel zoonotic infections spreading to human populations.
What is the One Health Model?
The main idea of the One Health model is that animal health, human health and environmental health are intrinsically intertwined. The movement promotes collaborations between researchers, practitioners, and policy makers from diverse specialisms. Through these links, it becomes easier to address and combat health challenges.
The basics of the One Health model have been around for decades, ever since the concept of zoonosis was first described in the 1800s. Even before that, people understood the links between animal health and human health. Many cultures had dietary laws and traditions which, in part, helped to reduce the spread of zoonotic diseases.
In 2004, the Wildlife Conservation Society in the US published their “12 Manhattan Principles” to combat threats to human and animal health. This really kicked off the modern One Health movement. Since then, many major organisations like the World Health Organisation (WHO) and the World Organisation for Animal Health (OIE) have become strong supporters.
Aside from the threat of zoonotic disease, there are many other aspects of health that fall under the principles of One Health. Antibiotic resistance, for example, is a problem both in both veterinary and human medicine. While some resistant pathogens can pass directly from livestock to humans and vice versa, that is not the only source of resistance. Residual antibiotics in animal products can enter the human food chain and cause increased resistance in human-specific bacteria.
On the environmental side, poor ecosystem health has a knock-on effect on animal and human communities. Although this is usually more immediate and obvious in agricultural communities, it still has an effect on the wider community as a whole. An example of this would be the widespread effects of pollinator loss. It is now well-known that pollinators such as bees are at risk from over-use of insecticides and from habitat loss. Fewer bees means less pollination, which in turn means lower crop yields. An enormous one third of all food is thought to be dependent on bees. Added to this, large quantities of feed for livestock are similarly dependent on pollination.
The Future of One Health
Changing the attitudes towards animal, human and environmental health can seem a daunting task. While the One Health model is still relatively obscure outside of professional organisations, it is gaining significant traction worldwide. Multiple organisations around the world have adopted One Health principles. Many veterinary and medical schools now teach it to students as part of their curriculum. Major global health challenges, like the COVID-19 pandemic, show how collaboration is necessary, not just across geographical lines, but interdisciplinary ones as well.