Table 1. Mainly causes and related effects influencing the emergence and reemergence of many diseases

Animal disease is a critical driver of poverty and a source of significant human morbidity and mortality, and thus deserves the re-invigorated focus brought by OH. In the face of a human population of nine billion in the next half century, finding ways to produce safe, secure and sustainable food through improved livestock systems will become an increasingly important role for OH. The recent shift in OH investment and effort towards endemic zoonoses, livestock diseases and food safety is a necessary development to ensure this approach remains relevant beyond the spectrum of emerging infections.

Successful public health interventions require the cooperation of the human health, veterinary health, and environmental health communities. According Center for Disease Control and Prevention (CDC), about 75 % of recently emerging infectious diseases affecting humans are of animal origin, and about 60 % of all human pathogens are zoonotic. What many do not realize is that these diseases do not just wreak havoc on human health. They leave collateral damage along the way, killing livestock, reducing the number of qualified health workers and educators, creating political unrest, and stopping the progress of developing nations. Most of the fundamental social and environmental determinants of health, such as water security, biodiversity, climate change, social justice, equitable access to resources, pollution and land use planning, have remained beyond the scope of most OH programmes, despite their profound impacts on human and animal health and welfare. Two factors that could be driving the more specific focus on infectious diseases in One Health are:

i ) the desire to reduce economic losses and to ensure access to markets by meeting the legislated obligations to attest to freedom from specific infectious diseases of animals, and

ii) the investment of resources from the public health sector for emerging zoonotic disease research and control programs. For years OH has focused its efforts on controlling disease rather than on protecting and promoting health. Health is more than the absence of disease. Health is a reflection of how individuals or populations interact with their world to cope and recover from stressors or changes, often what ecologists refer to as ‘resilience’ defined as the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and recovering quickly.

Although the concept of One Health was not new—the theory was supported by William Osler and Rudolf Virchow, the Father of Comparative Pathology, and re-articulated in Calvin Schwabe’s Veterinary Medicine and Human Health in 1984—our increasing interdependence with animals and their products has spurred the human medical and veterinary professions to readdress such an approach. This approach would encourage the collaborative efforts of multiple disciplines working locally, nationally and globally to attain the best possible health for people, animals and environment.

The benefits of a One Health approach include:

1. Improving animal and human health globally through collaboration among all the health sciences, especially between the veterinary and human medical professions, to address critical needs,

2. Meeting new global challenges head-on through collaboration among multiple professions—veterinary medicine, human medicine, environmental conditions, wildlife health and public health,

3. Developing centres of excellence for education and training in specific areas through enhanced collaboration among colleges and schools of veterinary medicine, human medicine and public health,

4. Increasing professional opportunities for veterinarians,

5. Adding to our scientific knowledge to create innovative programmes to improve health.

Actions against diseases at the animal–human–ecosystems interface must be based on prevention. The prevention of crossing ecosystem boundaries by diseases requires the existence of effective surveillance systems, focusing all relevant ecosystems involved or potentially involved and an appropriate multidisciplinary and inter-sectorial cooperation. During the surveillance of the animal–human–ecosystems interface, and when actions to prevent the crossing of ecosystem boundaries must be defined, no single method is valid for all diseases and situations. The approaches to be used are indeed rather intrinsic to the specific environment and disease we are facing and should be defined following an accurate retrospective and holistic analysis of the epidemiology of the disease under consideration, the environmental situation, the production systems involved (considered from farm to fork in case of food-borne diseases) and the historical information available. Finally, a proper integration of local needs with the requirements for international surveillance of EIDs is essential for a fair relationship between countries assuring local authorities active cooperation.

Recognizing that human health, animal health, and ecosystem health are inextricably linked, OH seeks to promote, improve, and defend the health and well-being of all species by enhancing cooperation and collaboration between physicians, veterinarians, other scientific health and environmental professionals and by promoting strengths in leadership and management to achieve these goals.

In conclusion we can statethat OH approach shall be achieved through:

1. Joint educational efforts between human medical, veterinary medical schools, and schools of public health and the environment;
2. Joint communication efforts in journals, at conferences, and via allied health networks;
3. Joint efforts in clinical care through the assessment, treatment and prevention of cross-species disease transmission;
4. Joint cross-species disease surveillance and control efforts in public health;
5. Joint efforts in better understanding of cross-species disease transmission through comparative medicine and environmental research;
6. Joint efforts in the development and evaluation of new diagnostic methods, medicines and vaccines for the prevention and control of diseases across species and;
7. Joint efforts to inform and educate political leaders and the public sector through accurate media publications.

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1. http://www.cdc.gov/onehealth/people-events.html
2. http://www.cdc.gov/onehealth/about.html
3. http://www.newsweek.com/healthcare-workers-fighting-ebola-biggest-battle-staying-healthy-282821
4. http://en.wikipedia.org/wiki/Resilience_%28ecology%29