1. Public Health Surveillance
Ashry Gad Mohamed
MB.ChB, MPH, DrPH
Prof. of Epidemiology

2. Contents Definition Importance Elements Objectives Types
Procedures of data collection
Analysis
Action
Reports

3. Public Health Surveillance
“Ongoing systematic collection, analysis, and interpretation of outcome-specific data for use in the planning, implementation, and evaluation of public health practice.”
CDC

4. Surveillance System
 Data Collection
 Analysis
 Dissemination

5. Surveillance for communicable diseases remains important…
The world population is highly mobile
International travel and troop movements increase the risk of communicable disease transmission
Migration for war and famine, and voluntary immigration increase communicable disease risk
Naturally occurring disease is not our only threat

6. Elements of surveillance
Cases and deaths due to a given disease.
Laboratory results.
Prevention and control measures.
Environment.
Vector.
Reservoir.
Population

7. Public Health Surveillance
Conceptual Taxonomy
Public Health Surveillance
Medical Utilization
and Adverse Events
Disease
Drug
Vaccine
Other
Products/Services
Traditional
‘Syndromic’
Infectious Disease
Other
Birth defect
Injuries
Etc.

8. Objectives of surveillance
Identify diseases of public health importance.
Identify quickly any outbreak, epidemic or unusual event.
Identify risk factors.
Identify high risk population.
Monitor disease trend.
Access current disease control activities.

9. What data do we collect?
Should be preceeded by careful selection of diseases or conditions.
Should be indicated.
Specify the indicator for each item wanted to be monitored.
It may requires In-Depth interview, if decision to investigate causes is taken.

10. Types of Surveillance Passive Inexpensive, provider-initiated
Good for monitoring large numbers of typical health events
Under-reporting is a problem
Active
More expensive, Health Department-initiated
Good for detecting small numbers of unusual health events
Enhanced
Rapid reporting and communication between surveillance agencies and stakeholders
Best for detecting outbreaks and potentially severe public health problems

11. Data collection Routine reporting system Advantages:
Hospitals, health centers, health facilities, CHW.
Advantages:
Inexpensive efficient.
Standardized.,
Disadvantages:
Incomplete
Busy doctors & nurses

12. New and complex disease entities must also be monitored…
New syndromes may emerge that present in an atypical manner
Syndromic surveillance uses health-related data that precede diagnosis and signal a sufficient probability of a case or an outbreak to warrant further public health response

13. Example of Passive Surveillance
Day 1- feels fine
Day 2- headaches, fever - buys Tylenol
Day 3- develops cough - calls nurse hotline
Day 4- Sees private doctor – dx with “flu”
Day 5- Worsens - calls ambulance seen in ED
Day 6- Admitted - “pneumonia”
Day 7- Critically ill - ICU
Day 8- Expires - “respiratory failure”
Case enters surveillance system through an EDC

14. Example of Syndromic Surveillance
Day 1- feels fine
Day 2- headaches, fever - buys Tylenol
Day 3- develops cough - calls nurse hotline
Day 4- Sees private doctor - dx “flu”
Day 5- Worsens - calls ambulance - seen in ED
Day 6- Admitted - “pneumonia”
Day 7- Critically ill - ICU
Day 8- Expires - “respiratory failure”
Case is under immediate investigation by the LHD because of the pre-diagnostic information gathered
Pharmaceutical Sales
Nurse’s Hotline
Managed Care Org
Absenteeism records
Ambulance Dispatch (EMS)
ED Logs

15. 2-Sentnel reporting system
Selected health units
Advantages:
More consistent pictures.
Motivated.
Disadvantages:
Not representative
Changed with surved population

16. 3-Surveys and special studies
Broad estimate.
Measure reliability.
Relieve health care workers.
Disadvantages:
Large sample size.
Expensive

17. 4-Case and outbreak investigations
On occasion.
Used as a next step

18. Data collection procedures
Operational definition
Instruments
Registers
Questionnaires
Case investigation form
Pre-test the instrument

19. Data collection
Training
Supervision
Quality control
Reporting

20. Analyze the data Summary tables. Disease charts. Maps. Rates & ratios
More analysis for pattern and causes

21. Investigate causation
Case and outbreak investigations.
Verbal autopsy.

22. Develop an action plan
What?
Who?
When?
Where?
How?
Outline resources.

23. Prepare and present reports
Review objectives.
Review tables, graphs & maps.
Add short narrative to explain findings.
Describe action plan.
Disseminate the report