The “One Health” concept, introduced in early 2000, refers to a notion that has been understood for more than a century: human health and animal health are interdependent and linked to the ecosystems where they coexist.
Human health and animal health are interdependent and linked to the ecosystems where they coexist.
More specifically, One Health is defined as “the collaborative efforts of multiple disciplines”—medical, veterinary and research professionals, etc.—“working locally, nationally and globally, to attain optimal health for people, animals and our environment”.
The concept has recently acquired new importance in light of the changing dynamics of interactions between people, animals, plants and our environment.
Three changes stand out in particular:
1. The human population is growing and expanding into new geographical areas.
As a result of this trend, many people are now living in close contact with wild and domestic animals. Although these animals play a very important role in our lives, more human-animal contact means a greater likelihood that animal diseases—known as zoonoses—will be passed on to people. Nearly 300 diseases are known to affect both animals and humans. We have long understood that animal health is essential to maintaining public health. According to the World Organisation for Animal Health (OIE), 60% of known human infectious diseases originated in animals (domestic or wild), as did 75% of the pathogens that cause emerging infectious diseases in humans.
2. Our planet is undergoing climate and land-use change, leading to deforestation and more intensive livestock farming.
These changes in environmental conditions and habitats can make it easier for diseases to jump from animals to people. Intensive livestock farming has been associated with negative impacts on the environment and global human security. According to the United Nations Food and Agriculture Organisation (FAO), livestock farming generates more greenhouse gases than the global transport sector. The effects of intensive livestock farming include deforestation, high water consumption, and soil contamination via faeces (which release antibiotics and other waste into the soil) as well as ammonia from animal feed. In addition, the overuse of antibiotics in animals and the emergence of zoonoses pose serious problems for human health. Deforestation has many negative effects on the environment. One of the biggest impacts is habitat loss, which affects millions of species. These species are forced to seek out new niches closer and closer to human settlements, bringing them into contact with people and increasing the risk of zoonoses.
3. Global movements of people, animals and food have increased dramatically.
International travel has become far more common in recent decades, allowing diseases and vectors of transmission to rapidly spread across borders worldwide. In our increasingly interconnected and interdependent world, the outbreak of an infectious disease in one country can become a health emergency of great concern to the entire world (e.g. COVID-19).
More human-animal contact means a greater likelihood that animal diseases—known as zoonoses—will be passed on to people
In short, these changes have facilitated the transmission of diseases between animals and humans by providing new opportunities for contact between people, animals and the environment.
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The areas in which the One Health approach is especially needed are food safety, zoonosis control and the fight against antimicrobial resistance.
A Comprehensive Solution to Antimicrobial Resistance
On the antimicrobial resistance front, it is well known that most of the antimicrobial agents used in veterinary medicine and human health care belong to the same families and share similar mechanisms of action. This increases the risk of resistant bacteria moving between humans and animals via the food chain or other routes of transmission (faeces, direct contact, etc.). It is highly worrying that some of the antimicrobial agents most commonly used in animals— colistin, for example—are the same ones reserved for the most difficult cases in humans. Transferable resistance mechanisms have been detected in bacteria of human and animal origin found in many different countries across the globe.
It is highly worrying that some of the antimicrobial agents most commonly used in animals—colistin, for example—are the same ones reserved for the most difficult cases in humans
One of the practices that has driven the increase and spread of antimicrobial resistance since the mid-20th century is the widespread use of antibiotics as “growth promoters” to stimulate weight gain. Antibiotics have also been used in animals to prevent disease. This has led to the selection of resistant bacteria in animals, which reach humans via the food chain.
In conclusion, we urgently need a transdisciplinary approach to improving the health of people, animals and our environment. We need One Health.