One Health

One Health is an approach calling for "the collaborative efforts of multiple disciplines working locally, nationally, and globally, to attain optimal health for people, animals and our environment", as defined by the One Health Initiative Task Force (OHITF). It developed in response to evidence of the spreading of zoonotic diseases between species and increasing awareness of "the interdependence of human and animal health and ecological change". In this viewpoint, public health is no longer seen in purely human terms. Due to a shared environment and highly conserved physiology, animals and humans not only suffer from the same zoonotic diseases but can also be treated by either structurally related or identical drugs. For this reason, special care must be taken to avoid unnecessary or over-treatment of zoonotic diseases, particularly in the context of drug resistance in infectious microbes.

A number of organizations throughout the world support the objectives of "One Health" including the One Health Commission (OHC), One Health Initiative, One Health Platform, CDC One Health Office, Society of Infectious Diseases Pharmacists (SIDP), and the Quadripartite Organizations. The Quadripartite Organizations are:

In particular, the One Health High Level Expert Panel, an independent advisory group to the Quadripartite Organizations, provided a comprehensive definition of One Health, whereby:

"One Health is an integrated, unifying approach that aims to sustainably balance and optimize the health of humans, animals, plants and ecosystems. It recognizes the health of humans, domestic and wild animals, plants and the wider environment (including ecosystems) are closely linked and interdependent. The approach mobilizes multiple sectors, disciplines and communities at varying levels of society to work together to foster well-being and tackle threats to health and ecosystems, while addressing the collective need for clean water, energy and air, safe and nutritious food, taking action on climate change, and contributing to sustainable development."

In the 19th century, two leading physicians first noticed and discussed the relationship between human health and animal health: Rudolf Virchow and William Osler (who was Virchow's student). Osler has been credited through word of mouth in the medical community with coining the term "One Medicine", though no direct evidence has been found for this.

In its contemporary form, the concept of "One Health" is generally credited to the work of Calvin Schwabe at the University of California, Davis in the 1960s and 1970s. Schwabe, a veterinarian trained in public health, coined the term "One Medicine" in a veterinary medical textbook in 1964 to reflect the similarities between animal and human medicine and stress the importance of collaboration between veterinarians and physicians to help solve global health problems. He established a department at UC Davis to jointly address issues in the animal and human health sciences. Schwabe went on to fully rethink and develop the concept of One Medicine in 1976. Since 2009, UC Davis has continued to support the One Health movement through its One Health Institute.

In 2004, The Wildlife Conservation Society held a conference called "One World, One Health" at Rockefeller University in New York. Out of that conference the twelve Manhattan Principles were created to describe a unified approach to preventing epidemic diseases. These principles emphasized links between humans, animals, and the environment, their importance in understanding disease dynamics, and the need for interdisciplinary approaches to prevention, education, investment, and policy development.

Due to global scares surrounding the H5N1 influenza outbreaks of the early-mid 2000s, the American Veterinary Medical Association established a One Health Initiative Task Force in 2006, the American Medical Association passed a One Health resolution to promote partnering between veterinary and human medical organizations in 2007, and a One Health approach was recommended for responses to global disease outbreaks in 2007. Building on these initiatives, the Food and Agriculture Organization (FAO), World Organisation for Animal Health (OIE), and World Health Organization (WHO) came together with the United Nations Children's Fund (UNICEF), United Nations System Influenza Coordination, and the World Bank to develop a framework entitled Contributing to One World, One Health-A Strategic Framework for Reducing Risks of Infectious Diseases at the Animal-Human-Ecosystems Interface in 2008, reiterating recommendations for a One Health approach to global health. This framework was expanded and implementable policies were developed at Stone Mountain, Georgia in May 2010. International meetings on One Health were held in 2011 in Africa and Australia.