KEY ISSUES IN PUBLIC-HEALTH SURVEILLANCE FOR THE 1990S

In this paper we propose a wider scope for public health surveillance in order to incorporate demographic and health systems monitoring alon g with activities conventionally associated with epidemiologic surveil lance. This new conception stems, in turn, from a revised definition o f public health, which describes-not a sector of activity or a type of health service-but a level of aggregation based on the population at large. In our review of the ideas that lead to the institutionalizatio n of health surveillance, we stress the broad concepts developed by su ch pioneers as Graunt and Petty. Their original concepts emerged from their active concerns for the public's health at a time when no scient ific theory of contagion was available-let alone any knowledge about h ow to treat persons for the major diseases that affected them. Later o n, and largely as the result of impressive advances in biomedical know ledge, surveillance activities tended to specialize and to concentrate predominantly on disease outbreaks and on salient adverse health cond itions. Health surveillance became closely associated with epidemiolog ic surveillance, which in turn became associated with the ability to r espond promptly to adverse health outcomes. Recently, we have witnesse d a gradual broadening of both the concepts and the practice of health surveillance. Paradoxically, the newer proposals tend to recapture pa rt of the spirit and scope of earlier definitions, prompted perhaps by such thoughtful historic parallels as the newly emerging health probl ems for which we have no clear-cut solution. If one element has to be stressed to promote the objectives of health surveillance today, it is the need to anticipate health outcomes and not just respond to them. This, in turn, requires an increased attention to the surveillance of risk factors, and a greater understanding of the complex causal relati onships that those factors -including behavioral, lifestyle, and envir onmental ones-with adverse healt outcomes and disability. Needless to say that, the first and foremost aim of health care-and of modern surv eillance-is to promote the well-being of individuals by improving thei r health.