The Health of Nature Is Our Health: Understanding One Health

Quick Summary

• Connected Health: The health of humans, animals, and the environment is deeply connected, so taking care of wildlife and ecosystems ultimately supports our own well-being.
• Risks from Habitat Loss: When forests are cleared and cities expand, animals come closer to humans, increasing the spread of diseases and causing declines in biodiversity that can disrupt the ecosystems we rely on.
• How to Help: People can make a difference by choosing sustainable food, reducing pollution, respecting wildlife, practicing good hygiene, raising awareness about these issues, and supporting conservation efforts.

One Health and Wildlife

At a wildlife rescue centre on the edge of a forest, a weak elephant once lay in the dust with a deep, infected wound above her leg. She was so exhausted that even standing was often too much for her. Veterinarians and volunteers worked for weeks to help her recover, carefully cleaning the wound and encouraging her to stand and eat. Some days, she managed to take a few slow steps toward the forest before exhaustion forced her back to the ground.

What first looked like a story of a single injured animal turned out to be something much bigger. Her survival depended on human care, but our own human well-being is also tied to the health of the animals and ecosystems she’s part of. 

This connection between animal health, human health, and environmental health is known as One Health.

So, what exactly is OneHealth?

At its core, One Health is a simple idea: human, animal, and environmental health are interconnected. To protect one, we need to protect them all. As pollution and resource depletion worsen, human health will be harder to maintain. We sometimes think we’re separate from nature and life on Earth, but that’s not the case—we share the same system. 

The connection becomes even more visible in natural ecosystems. For example, a polluted ocean doesn’t harm just aquatic animals—it affects the whole food web, and, essentially, humans are not separated from it. Toxins like heavy metals and microplastics can build up in fish and other sea creatures and eventually reach the food we eat. 

Land ecosystems also have similar connections. Many animals have a crucial role in maintaining the health of their living habitats. For instance, orangutans and gibbons contribute to seed dispersal by moving through the forest and consuming fruit. When these seeds spread around the area, they help forests regenerate and keep plant life diverse.

Habitat Loss: Where the Real Risk Begins

Many emerging infectious diseases over the years share something in common: they originate in animals. We refer to these as zoonotic diseases, which means diseases or infections that can be transmitted naturally from animals to humans and vice versa. 

Recently, the risk of these diseases has been growing because climate change, urbanisation, travel, animal migration, and trade blur the boundaries between wildlife, domestic animals, and humans. 

One of the biggest drivers is habitat loss. When forests are cleared for agriculture, cities expand, and roads are built through natural landscapes, we deprive wildlife of its essential habitats. Animals don’t simply disappear because of this—they also move, often closer to the human settlements, farms, and livestock. The result is an opportunity for germs or pathogens, since living closer increases the chances that diseases circulate more widely. 

Human activities push these risks even further. Deforestation, urban expansion, and the wildlife trade bring species together that would rarely interact in the wild. Markets and transportation networks can become pathways through which disease-carrying pathogens move between animals and humans. 

Habitat destruction also affects the animals themselves. When forests and natural areas disappear, wildlife may struggle to find enough food and space. Overcrowding and stress weaken their immune systems, making them more vulnerable to disease. At the same time, damaged or fragmented ecosystems can allow disease-carrying species to thrive, making disease spread easier and threatening biodiversity.

When Disease Becomes a Conservation Threat

One risk is often overlooked: infectious diseases can devastate wildlife populations. For species that are already vulnerable, a severe outbreak may push them closer to extinction. 

This risk is already evident today. Tragically, cases have occurred in many parts of the world. In most severe cases, the disease outbreaks have driven species from decline to extinction. 

Some outbreaks have already shown how devastating this can be. Ebola, for example, has caused severe population declines among great apes in Central Africa, including the western lowland gorilla. Because they reproduce slowly, it can take several years for populations to recover from such losses. To protect vulnerable gorilla populations, researchers have developed preventive strategies, such as vaccination programs for mountain gorilla groups and emergency vaccination plans if Ebola appears.

Similar concerns have been raised elsewhere. In 2018, parasites and a dog disease called canine distemper virus spread among the last surviving Asiatic lion population in India, killing over 23 lions in just a period of three weeks. However, thanks to collaborative efforts, the population has since shown signs of recovery.

Conservation efforts can manage some outbreaks, but others have resulted in far more devastating consequences. One of the most striking examples is the fungal disease chytridiomycosis. Scientists believe this fungal disease is behind the decline of at least 500 amphibian species over the last 50 years, including 90 presumed extinctions. The fungus infects amphibians such as frogs and salamanders by attacking their skin, which they need to breathe and regulate water. The Golden Toad of Costa Rica is a well-known example, as it hasn’t been seen since the late 1980s. 

These patterns reveal something important: disease emergence is not only a medical issue. It is as much an environmental issue. How we modify the environment, interact with wildlife, and manage ecosystems all influence the conditions under which new diseases emerge.

When Wildlife Gets Sick, We Feel It Too

While some of the species became extinct, the story does not end there. Instead, the disappearance creates a void in the ecological balance—a domino effect, where each move has an impact on another. 

After frogs started to disappear, all the species that preyed on them started to lack food. On the other hand, some insect species started to increase significantly. Among these were mosquitoes, known carriers of diseases such as malaria and dengue fever. When their natural predators aren’t keeping them in check, their numbers can rise, potentially affecting nearby human populations as well. 

Not long after, more malaria cases were reported in those areas, raising concerns about possible links to mosquito-borne diseases. So what began as a disease affecting animals ended up affecting ecosystems and eventually the well-being of people. 

Beyond disease risk, biodiversity loss also affects food security, agriculture, and water systems. Many species are key players in pollination, seed dispersal, pest control, and soil health. When these ecological roles disappear, the systems that support human societies become more fragile. 

Some societies face these risks more strongly than others. Among them are usually indigenous communities, where the forest, rivers, and wildlife form the foundation of local food systems, cultural practices, and livelihoods. As hunting, fishing, and gathering remain important sources of nutrition, changes in the ecosystems can immediately affect their well-being.

At the same time, indigenous people possess extensive knowledge developed over generations of living closely with nature. This knowledge can play an important role in identifying any changes in the environment and supporting conservation efforts. 

In short, protecting wildlife and ecosystems is part of conservation. But at the same time, it is also about safeguarding the ecological processes we all depend on. 

How to Contribute to OneHealth?

Global challenges can seem and feel overwhelming.

Still, there are things everyone can do and therefore should do. The idea behind OneHealth shows that actions at different levels can make a difference. While governments, scientists, and conservationists usually play a big role, individuals can also contribute in a meaningful way. 

The Wild Is Not Separated From Us

The idea behind One Health reminds us that boundaries we often imagine between humans, animals, and nature don’t really exist. These connections are far tighter than we tend to realise. Until something begins to break, these connections are often invisible. Only then do we take action.

The concept of One Health invites us to rethink this relationship. Human progress has long relied on managing, extracting, or controlling nature. The growing number of environmental crises and emerging diseases is revealing how fragile that assumption really is. The health of forests, oceans, wildlife, and human societies is part of the same system, and recognising this connection is the first step toward protecting it.

Protecting nature is about protecting us all. Want to make a real difference? Join our volunteer, internship, or ecotravel programs and experience firsthand how you can help wildlife and ecosystems—be part of the change today!