Definitions of health, as well as methods to pursue it, differed according to the medical, religious, and natural-philosophical ideas groups held, the resources they had, and the changing circumstances in which they lived.
Public health is an interdisciplinary field. For example, epidemiology, biostatistics, social sciences, and management of health services are all relevant. Other important sub-fields include environmental health, community health, behavioral health, health economics, public policy, mental health, health education, health politics, occupational safety, disability, oral health, gender issues in health, and sexual and reproductive health.
Public health, together with primary care, secondary care, and tertiary care, is part of a country’s overall healthcare system. Public health is implemented through the surveillance of cases and health indicators, and through the promotion of healthy behaviors.
Common public health initiatives include the promotion of hand-washing and breastfeeding, delivery of vaccinations, promoting ventilation and improved air quality both indoors and outdoors, suicide prevention, smoking cessation, obesity education, increasing healthcare accessibility, and distribution of condoms to control the spread of sexually transmitted diseases.
There is a significant disparity in access to health care and public health initiatives between developed countries and developing countries, as well as within developing countries. In developing countries, public health infrastructures are still forming. There may not be enough trained healthcare workers, monetary resources, or, in some cases, sufficient knowledge to provide even a basic level of medical care and disease prevention. A major public health concern in developing countries is poor maternal and child health, exacerbated by malnutrition and poverty coupled with governments’ reluctance in implementing public health policies.