2. Public Health Surveillance
Dr. Salwa Tayel

3. Objectives: After studying this lesson you will be able to:
• Define public health surveillance and its main components (activities)
• List the main uses of surveillance data
• Describe sources for data that can be used for public health surveillance
• Describe the flow of information for reportable diseases

4. Public Health Surveillance
Ongoing, systematic collection, analysis, and interpretation of health-related data essential to the planning, implementation, and evaluation of public health practice,
with the timely dissemination of these data to those responsible for prevention and control.

5. Essential activities of surveillance
Identify; define and measure the health problem of interest;
Collect and compile data about the problem (and if possible, factors that influence it)
Analyze and interpret these data
Provide these data and their interpretation to those responsible for controlling the health problem and
Monitor and periodically evaluate the usefulness and quality of surveillance to improve it for future use.
N.B
surveillance of a problem does not include actions to control the problem.

6. Information for Action
Surveillance is
Information for Action

7. Summaries, Interpretations, Recommendations
Information Loop of Public Health Surveillance
(involving health care providers, public health agencies, and the public)
Summaries, Interpretations, Recommendations
Reports
Health Agencies
Health Care Providers
Public
Analysis

8. The components of surveillance and resulting public health action

9. Surveillance System Components
Population of interest
which generates events
Public health response
Interpretation for associations,
trends, unusual patterns, signals
Measurement
and recording
Analytical applications
Transactional data
Data Management
Quality checks
Editing
Data preprocessing for a
specific purpose
(‘views’, ‘data marts’)
8/4/1428
Dr. Salwa Tayel

10. Purposes of Public Health Surveillance
Public health surveillance provides and interprets data to facilitate the prevention and control of disease.

11. Uses of Public Health Surveillance
Assess and monitor public health problems
Estimate magnitude of the problem
Useful in setting priorities to facilitate planning
Portray the natural history of a disease
Detect epidemics/define a problem
Generate hypotheses, stimulate research
Evaluate programs, control measures
Detect changes in health practices & services

12. Evaluate control measures of MEASLES
United States, 50
100
150
200
250
300
350
400
450
500
Vaccine licensed
MEASLES — by year, United States, 1983–1998 5 10 15 20 25 30
Year
1983
1988
1993
1998
Reported Cases (Thousands)
Reported Cases (Thousands) 20 10
Source: CDC. Summary of notifiable diseases
1963
1968
1973
1978
1983
1988
1993
1998
Year

13. Identifying Health Problems for Surveillance
Selecting a Health Problem for Surveillance:
Conducting surveillance for a health problem consumes time and resources.
It is important to select and prioritizing health problems for surveillance
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Dr. Salwa Tayel

14. Criteria for selecting and prioritizing health problems for surveillance:
Public health importance of the problem:
incidence, prevalence,
severity, sequela, disabilities,
mortality caused by the problem,
socioeconomic impact,
communicability,
potential for an outbreak,
public perception and concern, and
international requirements.
8/4/1428
Dr. Salwa Tayel

15. Criteria for selecting and prioritizing health problems for surveillance:
Ability to prevent, control, or treat the health problem:
preventability and
Availability of control measures and treatment.
Capacity of health system to implement control measures for the health problem:
Immediate response
availability of resources
8/4/1428
Dr. Salwa Tayel

16. Sources and Methods for Gathering Data
Three main sources:
Individual Persons
Health-care providers, facilities, and records
— Physician offices
— Hospitals
— Outpatient departments
— Emergency departments
— Inpatient settings
— Laboratories
Environmental conditions
— Air
— Water
— Animal vectors
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Dr. Salwa Tayel

17. Methods used to collect the health-related data
Environmental monitoring
Surveys
Notifications
Registries.
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Dr. Salwa Tayel

18. Surveys
Surveys, uses a “structured and systematic gathering of information” from a sample of “a population of interest to describe the population in quantitative terms.”
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Dr. Salwa Tayel

19. Notification
A notification is the reporting of certain diseases or other health-related conditions by a specific group, as specified by law, regulation, or agreement.
Notifications are typically made to the state or local health agency.
8/4/1428
Dr. Salwa Tayel

20. Registries
Reregistery is a method for documenting or tracking events or persons over time.
Examples:
Registries of vital events (birth and death certificates) are required by law and contain important health-related information.
A disease registry (e.g., a cancer registry) tracks a person with disease over time and usually includes diagnostic, treatment, and outcome information.
8/4/1428
Dr. Salwa Tayel

21. Surveillance data usually collected are:
Vital events, births, deaths, marriages, divorce,...
Morbidity data; infections diseases, non-communicable diseases, birth defects, injuries,...
Mortality data

22. Analyzing and Interpreting Data
Analyzing by time
Analyzing by place
Analyzing by person

23. Interpreting results of analyses
Observed increases or decreases in disease incidence or prevalence might be an artifact.
Common causes of artifactual (not true) change in disease occurrence are:

24. Changes in local reporting procedures or policies (e. g
Changes in local reporting procedures or policies (e.g., a change from passive to active surveillance).
Changes in case definition (e.g., AIDS in 1993).
Increased health-seeking behavior (e.g., media publicity prompts persons with symptoms to seek medical care).
Increase in diagnosis.
New laboratory test or diagnostic procedure.
Increased physician awareness of the condition, or a new physician is in town.
Increase in reporting (i.e., improved awareness of reporting).
Outbreak of similar disease, misdiagnosed as disease of interest.
Laboratory error.

25. Disseminating Data and Interpretations
Data and interpretations should be sent to:
those who provided reports or other data (e.g., health-care providers and laboratory directors).
They should also be sent to those who use them for
planning or
managing control programs,
Administrative purposes,
or other health-related decision-making.

26. Types of Surveillance Passive (Routine reporting system)
Hospitals, health centers, health facilities.
Reporting is governed by existing local rules.
Advantages:
Inexpensive.
Standardized.
Good for monitoring large numbers of typical health events
Disadvantages:
Under-reporting is a problem
Incomplete data
Busy doctors & nurses
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Dr. Salwa Tayel

27. Types of Surveillance 2-Active (Sentinel reporting system):
Collection of data on a specific disease for a relatively limited period of time.
By selected health units, certain physicians,…
Advantages:
More consistent pictures.
Motivated.
Disadvantages:
Not representative
Active surveillance is relatively expensive practice.
It is usually limited to disease elimination programs and to short-term intensive investigation and control activities, or to seasonal problems, (e.g. Influenza, arboviruses).
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Dr. Salwa Tayel

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Dr. Salwa Tayel

29. The End
Thank You
8/4/1428
Dr. Salwa Tayel