Programs that provide for the ongoing, systematic collection, analysis, interpretation and dissemination of data regarding health-related events for use in public health action to reduce morbidity and mortality and to improve health. Public health surveillance activities are generally authorized by legislators and carried out by public health officials; and may vary by jurisdiction. Included may be surveillance of infectious, chronic, or zoonotic diseases; injuries; exposures to toxic substances; health promoting or damaging behaviours; and other events associated with public health action.
Programs that utilize one or a combination of diagnostic tools to test large groups of people who are assumed to be well for the presence of a particular disease or condition or for certain risk factors that are known to be associated with that disease or condition; or which conduct in-depth tests to establish the cause and nature of an individual's presenting illness. The purpose of screening is to identify people who have a potential problem and refer them for early diagnosis and treatment and, where possible, to provide preventive measures. Early identification is particularly important when dealing with conditions that are more difficult to treat when fully developed. The purpose of more in-depth diagnostic work is to establish a logical basis for ongoing treatment.
The above terms and definitions are part of the Taxonomy of Human Services, used here by permission of INFO LINE of Los Angeles.