Table 3. Public Health Surveillance Definitions.

	Public Health Surveillance: CDC Definitions
	1988[56]	1992[35], 2012[57]	2001[26]	2011[58]	2008, 2012[37] **
Process	The ongoing systematic collection, analysis, and interpretation	The ongoing, systematic collection, analysis, and interpretation	The ongoing, systematic collection, analysis, interpretation, and dissemination	The ongoing, systematic collection, analysis, and interpretation	The systematic, ongoing collection, management, analysis, and interpretation
Knowledge	Of health data	Of health data essential to the planning, implementation and evaluation of public health practice	Of data regarding a health-related event	Of health-related data	Of data
Purpose	Closely integrated with the timely dissemination of these data both to those providing the data, and to those who can apply the data to control and prevention programs	Closely integrated with the dissemination of these data to those who need to know, and linked to prevention and control *	For use in public health action, to reduce morbidity and mortality, and to improve health	With the a priori purpose of preventing or controlling disease or injury, or of identifying unusual events of public health importance, followed by the dissemination and use of information, for public health action	Followed by the dissemination of these data to public health programs, to stimulate public health action

The complete definition in Thacker and Berkelman's 1992 book chapter is “the final link of the surveillance chain is the application of these data to prevention and control. A surveillance system includes a functional capacity for data collection, analysis, and dissemination linked to public health programs”.

Definition that Thacker et al. (2012) cite from the 2008 Dictionary of Epidemiology, 5^th ed.