Disease Surveillance Overview

Surveillance of Disease

• Surveillance is the process of collecting, analyzing, interpreting, and reporting data on the incidence of death, diseases, and injuries.
• It is considered the foundation of disease control efforts
• The CDC (Centers for Disease Control and Prevention) is the federal agency responsible for surveillance of most acute diseases.
• The CDC conducts surveillance if requested by a state or if an outbreak has the potential to affect more than one state.
• Data are passed from local and state governments to the CDC.
• The federal government has jurisdiction over interstate commerce, including interstate implications.
• State governments have jurisdiction over intrastate implications.

Creating a Surveillance System

• Clear objectives regarding the diseases or conditions to be covered are essential.
• The case definition is usually based on clinical findings, laboratory results, and epidemiologic data on:
  • Time
  • Place
  • Characteristics of affected persons

Methods and Functions of Disease Surveillance

• Active Surveillance:
  • Requires periodic telephone calls, electronic contact, or personal visits to obtain data.
  • More labor-intensive and costly.
  • Less frequently used for routine purposes.
• Passive Surveillance:
  • Physicians, clinics, laboratories, and hospitals are required to report diseases.
  • Expected to record all cases of reportable disease that come to their attention

Detection and Documentation of Outbreaks

• The percentage of patients with reportable diseases actually reported varies considerably.
• Seasonal variation is common amongst many infectious diseases.

Characterize Epidemic By Time, Place, and Person

• Time:
  • Epidemic time curve can be used to track the spread of an outbreak.
  • Example: Figure 3-14 shows shigellosis among students at a summer camp.
• Place:
  • Spot map and incidence rates by location are helpful tools.
  • Example: John Snow's spot map of cholera deaths in London, 1854
• Person:
  • Knowing the characteristics of affected persons clarifies the problem and its cause.
  • Example: Incidence of Measles in Residents of Cuyahoga County, Ohio, by Age Group.

Investigation of Epidemics

• Standard Approach to Investigation:
  • Making a diagnosis
  • Establishing a case definition
  • Determining whether there is a definite outbreak
  • Characterize time, place, and person
  • Develop and test hypotheses, pattern of spread, and mode of transmission
  • Test hypotheses using laboratory data or research methods

Surveillance for Bioterrorism

• Special surveillance techniques are being developed for rapid detection of major increases in the most likely biological agents.
• Syndromic surveillance:
  • Goal is to characterize "syndromes" consistent with agents of particular concern and to prime the system to report any such syndromes quickly
  • Provides an early warning of bioterrorism problems.

The Failure of a Vaccine to Produce Satisfactory Immunity

• This can be detected by:
  • A lack of change in disease rates
  • An increase in disease rates after an initial decrease
  • An increase in disease rates in a recently vaccinated group

Importance of Surveillance

• Setting disease control policy:
  • Surveillance data can inform policies to protect public health.
• Investigation of Disease Outbreaks:
  • Surveillance data and information are crucial for effective investigation and response to outbreaks.
• Communication with Appropriate Authorities:
  • Key for successful implementation of disease control measures
  • Includes communicating with:
    • Appropriate authorities
    • Appropriate health professionals
    • Public
• Professional Knowledge:
  • Contributes to the fund of knowledge about the causes and control of outbreaks

Example of Preparedness and Response to a Global Health Threat

• Surveillance of Disease Activity is the foundation of public health control of disease.
• Example: Figure 3-14 shows the impact of the two types of polio vaccines in the United States, and how the introduction of vaccines affected rates of paralytic disease.
• The figure also illustrates how recurrent polio spikes occurred after the initial introduction of vaccines, and how the continued use of the oral vaccine resulted in the eventual decline of polio cases.

Explore the critical process of disease surveillance, which involves collecting and analyzing data on diseases and injuries. This quiz covers the roles of the CDC and the importance of clear objectives in creating effective surveillance systems.