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Principles of Disease Surveillance

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Disease Indicators

• The measures that you use to monitor a disease e.g.

• Number– No of cases of malaria reported– No of cases of P. falciparum malaria reported

• Rate– Number of cases of ARI in children under 5 years per

100,000 population

• Ratio– Proportion of children with ARI who die

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Disease Indicators

• They may be indicators of – Disease incidence

• Cases of TB per 100,000 population

– Effectiveness of treatment• Case fatality in measles

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Surveillance: Indicators

Specific

Measurable

Action oriented

Realistic

Timely

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Surveillance: General principle

Health Care System Public Health Authority

Data Information

DecisionAction

Feedback

Reporting

EvaluationAnalysis & Interpretation

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Surveillance: Data

Health Care System Public Health Authority

Information

DecisionAction

HEALTH EVENT

•Disease

•Syndrome (e.g., AFP, jaundice, VHF)

•Public health issue (e.g., AMR)

•Environment (e.g., animal vector, water)

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Surveillance: Data

Health Care System Public Health Authority

Information

DecisionAction

DATA SOURCE

•Notifiable disease reporting system

•Vital statistics

•Survey

•Laboratory

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Surveillance: Data

Health Care System Public Health Authority

Information

DecisionAction

CASE DEFINITION•Clinical/laboratory

•Levels (suspected, probable, confirmed)

•Indicators

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Exposed

Clinical specimen

Disease

Pos. specimen

Infected

Seek medical attention

Report

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Surveillance: General principle

Health Care System Public Health Authority

Data Information

DecisionAction

Feedback

Reporting

EvaluationAnalysis & Interpretation

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Surveillance: Reporting

Health Care System Public Health Authority

Data Information

DecisionAction

Reporting frequency

•immediate

•weekly

•monthly ...

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Surveillance: Reporting

Health Care System Public Health Authority

Data Information

DecisionAction

Reporting methods•Paper

•Telephone, Fax

•E-mail ...

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Ministryof Health

WHO

Peripheral level

Intermediate level

Central level

Regional/International level

Surveillance: Data flow

Clinical (suspected)

+ Supportive laboratory data + epidemiological link (probable)

Diagnostic Laboratory (confirmed)

Regional reference laboratory

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Ministryof Health

WHO

Peripheral level

Intermediate level

Central level

Regional/International level

Surveillance: Tasks

Detect TreatReport

AnalyseInvestigateReportRespondFeedback

AnalyseInvestigateConfirmRespondPlan and FundFeedback

Analysis and feedback SupportPolicy and targetsFunding

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Surveillance: General Principle

Health Care System Public Health Authority

Data Information

DecisionAction

Feedback

Reporting

EvaluationAnalysis & Interpretation

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Surveillance: Analysis & Interpretation

Health Care System Public Health Authority

Data

DecisionAction

• Data characteristics

• Data validation

• Descriptive analysis

• Hypothesis generation

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Surveillance: Analysis & Interpretation

Health Care System Public Health Authority

Data

DecisionAction

• Various sources of notifications

•Various levels of quality

•Continuous data collection subject to change

Data characteristics

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Surveillance: Analysis & Interpretation

Health Care System Public Health Authority

Data

DecisionAction

• Missing values

• Bias

• Duplication

Data validation

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Surveillance: Analysis & Interpretation

Health Care System Public Health Authority

Data

DecisionAction

• Time

• Place

• Persons

Descriptive analysis

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Surveillance: Analysis & Interpretation

Health Care System Public Health Authority

Data

DecisionAction

• related to time

• related to place

• related to persons

Hypothesis generation

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Surveillance: General Principle

Health Care System Public Health Authority

Data Information

DecisionAction

Feedback

Reporting

EvaluationAnalysis & Interpretation

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Surveillance: Action

Health Care System Public Health Authority

Data Information

Decision

• Control

• Feedback

• Policy

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Surveillance: Action

Health Care System Public Health Authority

Data Information

Decision

Control• Rapid response

• Case management

• Prevention (e.g. immunization)

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Surveillance: Action

Health Care System Public Health Authority

Data Information

Decision

Feedback• Epidemiological bulletin

• Reports

• Website, others

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Surveillance: Action

Health Care System Public Health Authority

Data Information

Decision

Policy• Policy change

• Prediction, planning

• Epidemic preparedness

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Surveillance: Action

Health Care System Public Health Authority

Data Information

DecisionAction

Evaluation• results of action

• results of surveillance

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Surveillance: General Principle

Health Care System Public Health Authority

Data Information

DecisionAction

Feedback

Reporting

EvaluationAnalysis & Interpretation

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Surveillance: Function

Core function• Detection• Reporting • Investigation & confirmation• Analysis & interpretation• Action / response

Support function• Training• Supervision• Resources• Standards / guidelines

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Surveillance: Basic Ingredients

A good network of motivated people

Efficient communication system

Clear case definition and reporting mechanism

Basic but sound epidemiology

Good feedback and rapid response

Laboratory support

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Terima Kasih