Happy One Health Day! But wait, what’s One Health?

One Health Day will be acknowledged around the world on November 3rd to raise awareness of the multidisciplinary efforts to promote and maintain the health of humans, animals, and the environment.

I briefly alluded to One Health in an earlier post about rabies, but we need to discuss what One Health really is and how it’s actually helping you.

Imagine that a large chemical company dumped harmful chemical byproducts into your local river, which is where you regularly go fishing for trout and bass for family dinners. The chemicals in the environment end up in the fish you eat, which means you ultimately consume the mercury and other heavy metals that the company dumped into the river. While this does not involve infectious disease, it does address the chronic health problems from heavy metal exposure through subsistence fishing. Think of it this way – if the environment is sick, the animals get sick, and it ultimately makes you sick, too. This was just one of the many examples that highlight the interdependence between humans, animals, and the environment.

onehealth
Premise of the One Health framework: interdependence between animal health, human health, and environmental health.

Other environmental conditions like pollution, climate change, and land use changes (i.e. deforestation and construction) could lead to the emergence or re-emergence of pathogens and diseases. For example, the outbreak of Lyme disease is thought to have stemmed from land use changes. As we clear more forests to build houses, shopping malls, and subdivisions, we inadvertently send the white-footed mice scattering into new areas to find a new home. However, this particular mouse is the reservoir for Lyme disease, which means it harbors the pathogen without getting sick from it. The white-footed mouse is also really lousy at cleaning and grooming itself, so ticks love to latch on for a good blood meal without fearing that they’ll get pulled out or combed away.

If you can imagine this playing out, it’s a nicely orchestrated chain of events. A mouse living in a forest needs to run away to a new place because its home is destroyed by land clearing and construction. The mouse takes the ticks with it, or if it has no ticks on it, it certainly picks up new ones wherever it decides to resettle. These ticks then suck up infected mouse blood and then transfer the Lyme disease pathogen to other animals and humans. The One Health framework seeks to help stop the spread of Lyme and other health problems by addressing the environment, the animals, and the humans that share common spaces. But before we continue with ways One Health seeks to improve health, let’s take a look at how the framework came to be.

Since the beginning of mankind, people have tried to explain the cause of diseases and plagues. Ancient civilizations had always considered animals and humans as inherently different because of the religious belief that animals had no souls; therefore, animals were only considered useful for transportation, labor, and food. But Aristotle was interested whether a connection existed between animals and humans, so he performed dissections and anatomical research. He paved the way for future scientists like Galen, Andreas Vesalius, and William Harvey, who discovered undeniable similarities between animal and human anatomies. Clearly, animals and humans were more similar than previously thought.

Fast-forward to the 1700s when animals took a more central role in society. For example, Claude Bourgelat established the first veterinary faculty in France, thus paving the way for formal education in veterinary science. Around that time, English physician Edward Jenner made observations about smallpox and cowpox. He noticed that milk maids who handled cattle had a condition known as cowpox, but they never got sick with smallpox. Thinking that cowpox could be protective, he created the fist successful vaccination against smallpox. These animal-human observations and educational opportunities helped scientists and researchers open new possibilities in science and health.

In the 1800s, English physician John Snow conducted groundbreaking research in a fatal cholera epidemic that swept through Soho. He determined that the water was the cause of cholera and anyone who drank from it was at an increased risk of getting the disease and subsequently dying from it. Snow is credited with being the father of epidemiology, but his research was also integral in connecting the environment to human health. Meanwhile, a prominent German physician, Rudolf Virchow, dedicated his research to examining the similarities between animals and humans. In doing so, he coined the term “zoonosis,” which describes a disease that can be passed between animals and humans.

In the mid-1900s, Calvin Schwabe was the first to coin the term “One Medicine,” which emphasized the need to address both animal and human health when considering infection prevention strategies. Although Schwabe missed the environmental component, it was one step closer to One Health.

Until the 21st century, we saw bits and pieces of scientific achievement in human, animal, and environmental health. Although the three disciplines were never combined or used in tandem, these different pieces of research helped to propel us into the 21st century, riding on a wave of technological and scientific innovation.

However, as the Avian Influenza pandemic swept throughout the planet in 2003, international agencies like the World Health Organization (WHO), the Food and Agricultural Organization (FAO), and the World Organization for Animal Health (OIE) all sought to control the outbreak.

While the WHO sought to help people, the FAO and OIE worked to cull infected animals and stop the spread of disease from birds to humans. However, each organization worked alone, trying to secure funding and conduct their own research during this tumultuous time. Looking back on the pandemic and all that happened, the three organizations realized they were working toward similar goals but never thought to work together. In 2008, the WHO, FAO, and OIE decided to create the “One World – One Health Framework,” which helped to propel the concept of One Health to the forefront of public health research.

In the past, scientific achievements were entrenched in their own disciplines without connecting their implications or improvements to other fields that could have benefitted. Now, we aim to share what we find in order to coordinate our efforts across all major disciplines in hopes that we can better address disease and maintain public health.

One Health formally promotes the collaboration among human, veterinary, and environmental professions to ensure wellness and health while controlling and preventing disease. The idea that research should be shared across disciplines will hopefully help to unite professionals in working toward similar research goals. Opening these multidisciplinary communication channels will help to coordinate education, policy, and research efforts to better address the needs we face today.

With nearly 75% of new diseases originating from animals, a changing climate, and a global human population expected to reach 9 billion by 2050, we need to continue integrating research efforts across human, animal, and environmental fields to best address the coming changes.

So November 3rd is really a day of reflection and awareness of how far we’ve come as a society. It’ll be celebrated through various events held in various parts of the globe to highlight the importance and necessity of One Health.

It’s reassuring to know that despite looming outbreaks on the horizon, we will not face them alone.

 

Stay healthy!

 

If you want to learn more about One Health, take a look at the timeline from the Centers for Disease Control and Prevention website found here.

Cover Image credited to the One Health Commission.

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