Toward a “One Health” Approach to Stress Management to Better Manage Epidemics

The COVID-19 pandemic is a particularly relevant example of the impact of stress on our societies. While humans have faced the onslaught of the virus, the risk of illness, lockdowns, and social isolation, the animals living alongside them have not been spared. In addition to the disease’s impact on each individual, stress also causes immune deficiencies in animals, which may contribute to the spread of the viral infection. This shared stress has weakened an entire ecosystem and may have influenced the outcome of the pandemic. It must therefore be taken into account, not only for the physical and mental health of populations but also in epidemic management.   Stress is not necessarily harmful in and of itself. This stimulus, which disrupts homeostasis to elicit a response, drives us to take action—whether to engage in physical activity, avoid some kind of danger, or even go to work in the morning. The absence of stress is therefore not necessarily a good thing, as it can lead to boredom and frustration. The challenge, then, is to determine whether a given stress is a natural experience—often unavoidable and with positive effects—or whether it is instead a form of distress that leads to harmful effects. There are, of course, experiences that are inherently negative. Animals can experience psychological stress—from handling, transport, or weaning—or physical stress caused by hunger, thirst, fatigue, injury, extreme temperatures, or overcrowding. For example, intensive farming, which combines several of these situations, is one of the main stressors. But the difference between beneficial and harmful stress is sometimes more subtle. It may simply depend on the intensity or duration of the experience. When chronic stress occurs, for example, it alters hormone levels, affects the central nervous system, and suppresses the immune system, making humans and animals more vulnerable to disease. Stress can thus weaken the body’s resistance to pathogens. It must therefore be taken seriously in the context of a global pandemic—not only for the physical and mental health of populations but also for epidemic management. Stress can increase viral load and shedding in animals, which can result in high levels of contamination in livestock products, reduced production, fertility, and overall immunity in animals, thereby increasing the risk of disease transmission. Healthy livestock and pets therefore mean healthier and happier owners and more profitable livelihoods for farmers, not to mention that animal welfare reduces the need for antibiotics. Preventive disease management, based on animal welfare and complemented by the prudent use of antibiotics, would, in particular, enable a more effective fight against antimicrobial resistance—a growing problem affecting humans and animals worldwide. Antibiotic resistance clearly illustrates the need for shared disease management between human and animal populations. We must now look beyond a simple therapeutic response to an animal’s physiological or pathological conditions. Active disease surveillance, improved animal welfare, and stress reduction can collectively enhance the global health of animals. This is an issue that concerns us all, but animal owners have a particularly important role to play in ensuring the health and animal welfare of their own animals. Greater awareness of how we raise, feed, and care for animals can help reduce the stressors affecting them and the resulting negative consequences. Animal welfare is also important for its effects on humans. Shared health and the monitoring of potential pathogens capable of undergoing cross-species transmission make animal health a sentinel for human health—both physical and mental. Recently, spending more time with animals in our homes has helped alleviate moments of loneliness and stress caused by social isolation due to the pandemic. Just as with animals, our mental health can have a significant impact on our stress levels—and thus on our immune health and vulnerability to disease. In turn, humans’ psychological state can affect the other species around them. Stressed humans often harm animal welfare. Animals are known for their ability to sense negative emotions, and human stress can easily trigger stress and discomfort in animals. Human health, animal health, and environmental health are interdependent, and stress is a factor to consider in the “One Health” equation. It’s a virtuous cycle: adopting less stressful living conditions for animals will have positive effects on humans. These effects are particularly sought after and relevant in a world where zoonoses are more common and can lead to pandemic crises. It is becoming crucial to take proactive measures now to predict, detect, and manage threats to the mental health of all living beings, including stress. Being fully aware of the impact of stress on our societies and optimizing certain key control points could make all the difference in the future.