Public
health is "the science and art of preventing disease,
prolonging life and promoting health through the organised
efforts and informed choices of society, organisations, public
and private, communities and individuals."
It is
concerned with threats to the overall health of a community
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.
Public
health has many sub-fields, but is typically divided into
the categories of epidemiology, biostatistics and health services.
Environmental, social and behavioral health, and occupational
health, are also important fields in public health.
The focus
of public health intervention is to prevent rather than treat
a disease through surveillance of cases and the promotion
of healthy behaviors.
In addition
to these activities, in many cases treating a disease can
be vital to preventing it in others, such as during an outbreak
of an infectious disease. Vaccination programs and distribution
of condoms are examples of public health measures.
