Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals." It is concerned with threats to health based on population health analysis. The population in question can be as small as a handful of people, or as large as all the inhabitants of several continents (for instance, in the case of a pandemic).
Public health incorporates the interdisciplinary approaches of epidemiology, bio-statistics and health services. Environmental health, community health, behavioral health, health economics, public policy, insurance medicine and occupational health (respectively occupational medicine) are other important sub-fields.
The focus of public health intervention is to improve health and quality of life through the prevention and treatment of disease and other physical and mental health conditions, through surveillance of cases and health indicators, and through the promotion of healthy behaviors. Promotion of hand washing and breastfeeding, delivery of vaccinations, and distribution of condoms to control the spread of sexually transmitted diseases are examples of common public health measures.
Modern public health practice requires multidisciplinary teams of professionals including physicians specializing in public health/community medicine/infectious disease, epidemiologists, bio-statisticians, public health nurses, medical microbiologists, environmental health officers / public health inspectors, pharmacists, dental hygienists, dietitians and nutritionists, veterinarians, public health engineers, public health lawyers, sociologists, community development workers, communications experts, and others.