surveillance /sərvā″ləns/ [Fr, surveiller, to watch over] , 1. supervision or observation of a patient or a health condition. It may include the use of closed-circuit television cameras and monitors to cover unattended locations from a central office. 2. a detailed examination or investigation for the accurate collection of data to record changes in the character of a population as at a particular time or, in a prospective or longitudinal surveillance, over a period. Retrospective surveillance might study the characteristics of a population in which a previous event occurred. The collection of data may include hospital records, morbidity and mortality statistics, death certificates, records of immunization, age groups, and various ecological and weather factors for the period of investigation, particularly if insect vectors are possible influences.
