Surveillance by Jeremiah Kwenah censil lec note

Surveillance.ppt

1. SURVEILLANCE
ITS TYPES AND USES IN
PUBLIC HEALTH
Dr Mayur Vala
Resident
PSM Department
PDU Medical College
Rajkot
1Surveillance

2. Content:
- Definition
- History
- Types
- Public health Aims
- Criteria for undertaking
- Prerequisite for effective surveillance system
- Conducting a Surveillance
- Evaluation
- Uses
2Surveillance

3. Definition:
System of close CONTINUOUS observation of all aspects of
occurrence and distribution of disease through systematic
collection, tabulation, analysis and TIMELY dissemination of all
relevant data pertaining to disease control and prevention.
Simply surveillance is DATA COLLECTION FOR ACTION
The continuous scrutiny of all aspect of occurrence and spread
of the disease that are pertinent to effective control.
3Surveillance

4. 4
Data collection for Action flow chart
Surveillance

5. 5
History:
Origin:
From French word, surveiller
sur – over veiller – watch
First use of Public Health Action:
- William Farr
Recognition by WHO:
- In 21
st
World Health Assembly in 1968
Types:
- Routine
Active
Passive
- Sentinel
Surveillance

6. Routine:
Active-
- A system in which project staff make periodic field visit to
health care facilities to identify new cases of diseases or
deaths from disease that have occurred.

- Go and get data/information
Adv.:
More accurate than passive
Local outbreaks are identified
Assume complete reporting
Disadv.:
Required skilled personnel
Expensive
6Surveillance

7. Passive-
- Surveillance in which available data on reportable disease are
used or reporting is mandated or requested with the responsibility
for the reporting often falling health care provider or district health
officer.
- Simply pt. comes to the clinic and provide information
Adv.:
Simple
Less burdensome
Inexpensive
Disadv.:
Under-reporting
May not be representative
May fail to identify outbreaks
7Surveillance

8. Sentinel:
-Method of identifying missing cases and thereby

supplementing the notified cases.
- Helps in estimating total amount of disease in
community.
8Surveillance

9. Public Health Aims:
•Assess the Public health status
•Define Public health priority
•Evaluate Public health programme
•Stimulate research
Criteria for undertaking:
•Public health importance
- Burden of disease
- Severity, mortality
- Epidemic potential, threat
- Cost, socio-economic impact
•Feasibility
- Cost
- Availability of data
9Surveillance

10. Prerequisites of effective surveillance
system
•Standard case definition
•Enumeration of reporting units
•System for disease surveillance
10Surveillance

11. Conducting a surveillance:
1. Collection
* Requires reporting from individual to health
department to state health department.
* Reporting known or suspected cases is considered to be
an obligation of
• Physicians, dentists, nurses, and other health
professionals
• Medical examiners
• Administrators of hospitals, clinics, nursing homes,
schools, and nurseries.
• Laboratory directors
• Any individual who knows of or suspects the existence of a
reportable disease
11Surveillance

12. 2.Analysis
In term of Time, Place and Person
# Time
- To detect actual changes in disease incidence
- Comparing report for current week with preceding
weeks
- To analyze long term trends, year wise
# Place
- To determine where cases are occurring
# Person
- By Age, Sex, Risk factors, etc…
12Surveillance

13. 3. Interpretation
- When there is difference in expected pattern of disease-
investigate further
- Not all apparent increase in disease occurrence represent
true increase
- Local health dept. determine amount of excess necessary
for action
4. Dissemination
- Timely disseminate to health care provider, lab director,
health agency
13Surveillance

14. Evaluation of surveillance system:
WHY??
- To draw conclusion about its present state
- To make recommendation about its future potentials.
In a thorough evaluation, the following
facets of the system should be addressed :
• The public health importance of the health event under
surveillance
• The objectives of the system
• The system’s usefulness
• Qualities of the surveillance system
• Cost or resource requirements for system operation
14Surveillance

15. 1.Importance:
The importance of a health event
can be assessed with the following measures:
• The current impact of the health event
— Total number of cases: incidence, prevalence
— Severity of illness: case-fatality rate, death-to-case ratio
— Mortality: overall and age-specific mortality rates, years of
potential life lost
— Morbidity: hospitalization, disability
— Health care costs
• Its potential for spread
• Its preventability
15Surveillance

16. Cont…
2. Objectives:
Consider first what information is needed for effective prevention
and control, then to determine which objectives are most
appropriate.
3. Usefulness:
We address whether a surveillance system makes a difference.
We may assess usefulness by answering the following:
• What actions have been taken to date?
• Who has used the information to make decisions and take actions?
• What other future uses might the information have?
16Surveillance

17. Cont….
4. Qualities:
Several qualities or attributes affect the usefulness of surveillance
system.
- Simplicity
- Flexibility
- Acceptability
- Sensitivity
- Positive predictive value
- Timeliness
- Costs

17Surveillance

18. Uses:
1. Monitoring health events:
-We monitor health events for the following purposes:
- To detect sudden changes in disease occurrence and distribution
- To follow secular (long-term) trends and patterns of disease
- To identify changes in agents and host factors
- To detect changes in health care practices
2. Link to Public Health Action:
- Investigation and control
- Planning
- Evaluating prevention and control measures
- Generating hypotheses and stimulating public health research
3. Testing hypotheses:
4. Archive of disease activity:
18Surveillance

19. Thank You …….
19Surveillance