Posted by: glamielle | August 21, 2010

About One Health

In the traditional model for public health (left), there are minimal interactions between each field. A One Health approach (right) recognizes the inherent relationships between each field.

While not new, the principle of One Health has recently resurfaced. On its most basic level, it refers to the relationships between human, animal and environmental health. While the definition of global health may vary, my belief is that it is the application of One Health to a global scale.

The traditional view of public health is one that is often sheltered within its specific field. There is thus the belief that human health is only a matter of human health professionals, animal health a matter of veterinarians and environmental health a matter of environmentalists.

In such a situation, there is little communication between each field and in that sense they progress isolated, at a different pace and with little cooperation with each other.  Problems are viewed from one perspective and are managed in a unilateral fashion. This is, however, not a realistic representation of our world, where every system affects one another.

The advent of the Industrial Age has changed our world in dramatic ways. Science progressed to new exciting heights and human success has boomed. The other side of the coin is that the world has become overpopulated, leading to unequal development, rise in poverty and disease, decrease in food supply and environmental degradation. These are known as “wicked problems” and are multifactorial in nature. Unfortunately, there is rarely a simple answer to such complicated problems. It is only when looking at the world in a new way and appreciating its complexities that we come to realize that one-sided approaches cannot provide long-lasting solution to these problems.

There is thus the need to shift away from this traditional unilateral approach. One Health provides a more comprehensive perspective to public health, taking into account the intricate complexities of our world and using interdisciplinary tools to solve problems. In this model, humans and other animals live in a common environment. It is logical to assume that a change in one of these factors will affect the other two.

Veterinarians are lucky (well that’s how I see it at least…) in the sense that they find themselves at the center of these interactions. Indeed, they are on the frontlines of human health when it comes to zoonotic diseases, or diseases transmissible between animals and people. According to the World Health Organization, 70% of infectious diseases discovered in the past twenty years originated from animals. These include well-known illnesses such as HIV-AIDS, tuberculosis, plague, or influenza virus. If we are able to detect and identify outbreaks of such diseases in animals, we will be more likely to reduce their impact on the human population.

The bubonic plague, transmitted by the rat flea, is still largely present in the developing world (Photo from:

Public health is also strongly influenced by animal health. Indeed, many depend on animals for their subsistence and it is important to promote adequate animal health to ensure proper food safety and security.  Diseases such as rinderpest or foot and mouth disease are directly harmless to humans; however they can devastate agriculture and thus people’s livelihoods. Animal welfare is also an important part of promoting public health from this perspective and it is important to understand that, besides the obvious ethical issues, mistreated or stressed animals are more susceptible to illness.

While immune to the disease, people can be severely affected by Foot and Mouth Disease (FMD) through cattle and other animal losses (Photo from:

Perhaps the most complicated issue we are faced with is human impact on the environment and climate. It is difficult to project how environmental degradation will affect long-term public health. Losses in biodiversity have reached unprecedented levels through over-exploitation and habitat loss. Numbers are staggering, as illustrated by dwindling shark numbers worldwide (hundred million fished yearly) or bluefin tuna population in the Mediterranean. Wildlife species such as amphibians provide us with important bio-markers for environmental health and it is important to adequately study them if we are to better understand how environmental changes affect public health.

The chytrid fungus has been responsible for dramatic decreases in amphibian populations worldwide. Causes of this sudden spread of the disease are not well-known and some scientist implicate international travel and global weather changes. (Photo from:

To conclude, One Health gives us a complex world and appreciating how each part affects another can be difficult. While I am positive that we can do it, the question is: can we act accordingly. To tackle these “wicked problems”, a comprehensive and multidisciplinary approach is essential.

For more information about One Health, check out the Links section.

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