Introduction
Public and preventative health as a medical discipline is an  under-recognized yet vital career track for physicians in training.  Unlike traditional clinical medicine that focuses on disease  identification and management on the individual (patient) level, public  and preventive health seeks to promote the health of communities on a  local, regional, national and even global level.
This article introduces the concept of public health practice,  describes the training of public health physician practitioners in the  US and Canada, and concludes with recommendations for developing a more  global public health practitioner postgraduate training model.
What is the mission of public health?
This mission of public health is explained in the three core  functions of public health, defined in the Institute of Medicine  landmark publication, The Future of Public Health:
Assessment: Public health entities regularly and  systematically collect, assemble, analyze, and make available  information on the health of the community, including statistics on  health status, community health needs, and epidemiologic and other  studies of health problems (1).
Policy Development: Public health entities serve  the public interest in the development of comprehensive public health  policies by promoting use of the scientific knowledge base in  decision-making about public health and by leading in developing public  health policy (1).
Assurance: Public health entities assure their  communities that services necessary to achieve agreed upon goals are  provided, either by encouraging actions by other entities (private or  public sector), by requiring such action through regulation, or by  providing services directly (1).
How is the public health mission executed?
Public health is carried out within communities by performing ten essential public health services:
	- Monitor health status to identify and solve community health problems.
- Diagnose and investigate health problems and health hazards in the community.
- Inform, educate and empower people about health issues.
- Mobilize community partnerships and action to identify and solve health problems.
- Develop policies and plans that support individual and community health efforts.
- Enforce laws and regulations that protect health and ensure safety.
- Link people to needed personal health services and assure the provision of health care when otherwise unavailable.
- Assure competent public and personal health care workforce.
- Evaluate effectiveness, accessibility, and quality of personal and population-based health services.
- Evaluate effectiveness, accessibility, and quality of personal and population-based health services (2).
What skills do public health physicians need in order to execute the public health mission?
Successful public health physicians require specific skills  beyond scientific knowledge and clinical care. The eight core  competencies of public health professionals, some of which are similar  to the ACGME competencies, are:
	- Analytic/Assessment Skills
- Policy Development/Program Planning Skills
- Communication Skills
- Cultural Competency Skills
- Community Dimensions of Practice Skills
- Public Health Sciences Skills
- Financial Planning and Management Skills
- Leadership and Systems Thinking Skills (3)
Public health physicians develop these competencies in the study  of environmental health, health communication social and behavioral  sciences, health policy and management, epidemiology and biostatistics,  infectious disease and international health, risk policy and management,  and population and reproductive health.
How do physicians achieve public health professional competencies?
Many physicians from a wide variety of medical fields pursue a  Masters in Public Health at some point in their career either to enhance  their understanding of public health, or to obtain needed skills in  their professional development. Physicians who complete a Masters degree  in Public Health are more likely to practice in a primary care field,  be employed in academia, conduct public health research, receive NIH or  other funding, and have more peer-reviewed or scholarly work, compared  to their non-MPH physician counterparts (4).
Public health practitioner postgraduate specialty training exists  in several countries, including the United States and Canada. The  Canadian system offers a 5-year direct-entry public health and  preventive medicine (PHPM) residency training experience, requiring at  least one year each of clinical training, academic work, and field-based  public health practicums. The additional years are flexible, but  involve further training in the three core requirements. Many PHPM  trainees choose to complete 2-years of clinical training to achieve  certification as a family practitioner, obtain a Masters in Public  Health, and then finish with relevant field work (5).
In the United States, residents can train in preventive medicine  (PM), which includes training aerospace medicine, occupational medicine,  and public health and general preventive medicine. Subspecialty  training is available in undersea and hyperbaric medicine, medical  toxicology, and clinical informatics. PM physicians obtain board  certification from the American Board of Preventive Medicine (ABPM),  which is a member of the American Board of Medical Specialties. The ABPM  also allows board certification via alternate pathways than a PM  residency, for those physicians considering a midcareer change in their  specialty or practice focus (5).
Why is global postgraduate training in public health important?
With a shift in global health care from the management of acute  illnesses and infectious diseases, to the management of chronic diseases  in aging populations with increasingly burdensome healthcare costs,  current and future generations of physicians need to develop skills in  population and public health (6). In the new era of medical educational  globalization, efforts should be directed at the training of a cadre of  public health physician practitioners who possess the knowledge, skills,  attitudes and experience in both public health and clinical medicine.  Public health physician specialists around the world should engage in  integrated international training experiences, not only to improve their  knowledge base, but also to share ideas, resources, and best practices  aimed at improving both local and worldwide health (5).
References
	- Institute of Medicine (U.S). Committee for the Study of the  Future of Public Health, Division of Health Care Services. The Future of  Public Health. 1988.
- Centers or Disease Control and Prevention. CDC - 10 Essential Public Health Services. 12/09/2010; Available at: here Accessed 03/26, 2013.
- The Council on Linkages Between Academia and Public Health  Practice. Core Competencies for Public Health Professionals. 05/2010;  Available at: here Accessed 03/26, 2013.
- Krousel -Wood M, He J, Booth M, Chen CS, Rice J, Kahn MJ, et al.  Formal public health education and career outcomes of medical school  graduates. PLoS One 2012;7(6):e39020.
- Loh LC, Peik SM. Public health physician specialty training in Canada and the United States. Acad Med 2012 Jul;87(7):904-911.
- Institute of Medicine (U.S). Committee on Integrating Primary  Care and Public Health, Board on Population Health and Public Health  Practice. Primary Care and Public Health: Exploring Integration to  Improve Population Health. 2012.
	Reviewed in April 2013 by:
		Kristina Sole, MD, FACOG
		Assistant Professor of Obstetrics & Gynecology, Director of Women's Health
		Director of Obstetrics & Gynecology Clerkship, Weill Cornell Medical College in Qatar
		Consultant at Hamad Medical Corporation - Women's Hospital