Lesson 5: Public Health Surveillance

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Section 1: Introduction

Surveillance — from the French sur (over) and veiller (to watch) — is the “close and continuous observation of one or more persons for the purpose of direction, supervision, or control.”(1) In his classic 1963 paper, Alexander Langmuir applied surveillance for a disease to mean “the continued watchfulness over the distribution and trends of incidence [of a disease] through the systematic collection, consolidation, and evaluation of morbidity and mortality reports and other relevant data.” He illustrated this application with four communicable diseases: malaria, poliomyelitis, influenza, and hepatitis.(2) Since then, surveillance has been extended to non-communicable diseases and injuries (and to their risk factors), and we now use the term public health surveillance to describe the general application of surveillance to public health problems.(3)

Evolution of Surveillance

The term surveillance was used initially in public health to describe the close monitoring of persons who, because of an exposure, were at risk for developing highly contagious and virulent infectious diseases that had been controlled or eradicated in a geographic area or among a certain population (e.g., cholera,plague, and yellow fever in the United States in the latter 1800s). These persons were monitored so that, if they exhibited evidence of disease, they could be quarantined to prevent spreading the disease to others.

In 1952, the U.S. Communicable Disease Center described its effort to redirect large-scale control programs for multiple infectious diseases, which had achieved their purpose, “toward the establishment sofa continuing surveillance program. The objective of this redirected program is to maintain constant vigilance to detect the presence of serious infectious diseases anywhere in the country, and when necessary, to mobilize all available forces to control them.”(4)

In 1968 at the 21st World Health Assembly, surveillance was defined as “the systematic collection and use of epidemiologic information for the planning, implementation, and assessment of disease control.” (5) In the 1980s and 1990s, Thacker (3) and others(6–8) expanded the term to encompass not just disease, but any outcome, hazard, or exposure. In fact, the term surveillance is often applied to almost any effort to monitor, observe, or determine health status, diseases,or risk factors within a population. Care should be taken, however, in applying the term surveillance to virtually any program for or method of gathering information about a population’s health, because this might lead to disagreement and confusion among public health policymakers and practitioners. Other terms (e.g., survey, health statistics, and health information system) might be more appropriate for describing specific information-gathering activities or programs.(9)

The essence of public health surveillance is the use of data to monitor health problems to facilitate their prevention or control. Data, and interpretations derived from the evaluation of surveillance data, can be useful in setting priorities, planning, and conducting disease control programs, and in assessing the effectiveness of control efforts. For example, identifying geographic areas or populations with higher rates of disease can be helpful in planning control programs and targeting interventions, and monitoring the temporal trend of the rate of disease after implementation of control efforts.

Those persons conducting surveillance should: (1) identify, define, and measure the health problem of interest; (2) collect and compile data about the problem (and if possible, factors that influence it); (3) analyze and interpret these data; (4) provide these data and their interpretation to those responsible for controlling the health problem; and (5) monitor and periodically evaluate the usefulness and quality of surveillance to improve it for future use. Note that surveillance of a problem does not include actions to control the problem.(2)

In this lesson, we describe these five essential activities of surveillance, enumerate the desirable characteristics of surveillance, and provide examples of surveillance for multiple health problems.

References (This Section)

  1. Merriam-Webster. Merriam-Webster’s Dictionary of English Usage. Springfield (MA): Merriam-Webster, Inc. 1976.
  2. Langmuir AD. The surveillance of communicable diseases of national importance. N Engl J Med 1963;268:182–92.
  3. Thacker SB, Berkelman RL. Public health surveillance in the United States. Epidemiol Rev 1988;10:164–190.
  4. Communicable Disease Center. Communicable Disease Center Activities 1952-1953. Atlanta: Department of Health, Education, and Welfare; 1953. Public Health Service Publication Number 391, p. 17.
  5. World Health Organization. Report of the technical discussions at the twenty-first World Health Assembly on ‘national and global surveillance of communicable diseases.’ Geneva: World Health Organization; 18 May 1968, p. A21.
  6. Thacker SB, Stroup DF, Parrish RG, Anderson HA. Surveillance in environmental public health: issues, systems, and sources. Am J Public Health 1996;86:633–8.
  7. Vaughan JP, Morrow RH. Manual of epidemiology for district health management. Geneva: World Health Organization; 1989.
  8. Wegman DH. Hazard Surveillance. In: Halperin W, Baker E, Monson R (editors). Public Health Surveillance. New York: Van Nostrand Reinhold; 1992, pp. 62–75.

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