Tổng quan về giám sát y tế công cộng (Overview of publich health surveilance)

• Explain the difference between surveillance and planned studies • Describe how surveillance is used in public health practice • Describe the key elements of the public health surveillance cycle • Describe the key features of the International Health Regulations • Explain the differences among different types of surveillance (active, passive, sentinel, etc.)

Overview of Public Health Surveillance

Matt Moore, Resident Advisor Field Epidemiology Training Program

Objectives: By the end of this session,

you should be able to:

• Explain the difference between surveillance and planned studies

• Describe how surveillance is used in public health practice

• Describe the key elements of the public health surveillance cycle

• Describe the key features of the International Health Regulations

(active, passive, sentinel, etc.)

What is public health surveillance?

How?

What?

Why?

What is public health surveillance?

How?

What?

Why?

Systematic, ongoing, collection, collation, and analysis of data and the timely dissemination of public health information for assessment and public health response as necessary

IHR 2005

How is surveillance different from

a planned study?

Surveillance

Planned Study

Collection, collation, analysis and timely

dissemination of public health information?

For assessment and public health response as

necessary

*Can be temporary in setting of outbreak investigations or in

preparation for a mass gathering, e.g., Olympic games

The reason for collecting, analyzing, and disseminating information on a disease is to control that disease Collection and analysis should not be allowed to consume resources if

action does not follow."

Foege W H., Hogan R C., Newton L H Surveillance Projects for Selected Diseases International

How have YOU used

surveillance?

Some uses of public health surveillance data

• Describe the burden of or potential for disease

• Monitor trends and patterns in disease, risk factors, agents

• Detect sudden changes in disease occurrence and distribution

• Provide data for program, policies, priorities

• Evaluate prevention / control efforts

The surveillance cycle

Reporting / Data Collection

Analysis, Interpretation Action!

Evaluation

Diagnosis / Detection

Communicating Information

International Health Regulations, 2005

• World Health Assembly, 2005: All 196 UN member states committed to achieving the goals of the revised International Health Regulations (IHR) over a five-year period

• IHR requires all countries to:

• Make sure surveillance systems and laboratories can detect potential threats

• Work together with other countries to make decisions in public health emergencies

• Report through participation in a network of National Focal Points

• Respond to public health events

Vocabulary is vital: the language of surveillance

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

• Where are the cases or events being detected?

• Is the underlying population clearly defined?

• Who initiates reporting of the cases or events?

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

Indicator-based surveillance

• Also known as case-based

surveillance

• Defined as routine reporting of

individual cases of disease

• Examples

• Individual cases of dengue from

southern Vietnam

• Individual cases of fever and rash

illness from one province

Event-based surveillance

• Event: a manifestation of disease

or an occurrence that creates a

potential for disease

• Examples:

• 3 cases of pneumonia among

children in the same school

• 100 chickens die on the same

WPSAR 2013;4(3):DOI.10.5365

Comparison of Event-based vs

Indicator-based Surveillance

Pathogens vs Syndromes

• Pathogens: Specific bacteria, viruses, etc

• Examples: Salmonella Typhi, Vibrio cholerae,

measles, influenza, Ebola

• Require a laboratory or (possibly a bedside

test) for diagnosis  laboratory-based

surveillance

What are all of the steps that must take place for

an individual case of influenza to be reported?

What are all of the steps that must take place for

an individual case of influenza to be reported?

• Now that you have outlined all of the steps needed to report

individual cases, how could cases of the following diseases be

missed?

• Influenza?

• Meningitis?

• Ebola?

Pathogens vs Syndromes

• Pathogens: Specific bacteria, viruses, etc

• Examples: Vibrio cholerae, Salmonella Typhi,

measles

• Require a laboratory or (possibly a bedside

test) for diagnosis  laboratory-based

surveillance

• Syndrome: A collection of signs and

symptoms that suggest a particular

disease process

• Examples: Severe Acute Respiratory Illness,

fever & rash illness, fever & jaundice

• Require a healthcare provider but not a

What kind of surveillance is being conducted?:

Some questions to guide you

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

• Where are the cases or events being detected?

• In the community?

• In a hospital?

• In a laboratory?

• Some combination?

Where are the cases or events being

detected?

Community-based surveillance Hospital-based surveillance

CEBS was designed to supplement the national surveillance system

by training community members to identify, within their own

communities, unsafe burials and persons with signs and symptoms

compatible with EVD [Ebola Virus Disease] infection.

Cases included in the surveillance were overnight inpatients with suspected respiratory infections An overnight admission is defined as: A patient who is admitted under a medical team, and to a hospital ward or assessment unit.

WPSAR 2014;5(2):DOI:10.5365

Where are the cases or events being

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

• Where are the cases or events being detected?

• In the community?

• In a hospital?

• In a laboratory?

• Some combination?

• Are cases reported from all sites (e.g., hospitals, clinics) within a geographic area?

Or are cases reported from just a subset (or sample) of sites?

Routine reporting of nationally notifiable

diseases:

A very common type of surveillance

• Routine reporting sometimes

also called universal reporting

• Important for diseases

prioritized by Government

• Also important for diseases

targeted for elimination

• Nationwide measles case-based

surveillance with laboratory

testing started in 1992, and virus

genotyping started in 2010.

• Progress Toward Measles Elimination

MMWR 2015;64(13):357-362

Sentinel Surveillance

• Sentinel = a soldier or guard whose job is to stand

and keep watch

• Sentinel surveillance

• Used when high-quality data are needed that cannot be

obtained through routine (or universal) reporting

• Data collected from a subset (a sample) of all possible

reporting units, e.g., hospitals = sentinel sites

• Reporting units have a high probability of seeing cases

of the disease in question, good laboratory facilities,

and experienced, well-qualified staff

• Sentinel systems deliberately involve only a limited

network of carefully selected reporting sites

Fireworks-related injury surveillance in the

Philippines: trends in 2010-2014

There were limitations in this study Only hospitalized patients were captured by the sentinel surveillance system Mild cases who did not require hospitalization were missed Also, the sentinel sites cover only 24 out of 81 provinces The notification rate estimates do not represent national fireworks-related injury burden; the only reflect

• Sentinel surveillance data from 50 hospitals:

• 33 national government

• 4 local government

• 13 private

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

• Where are the cases or events being detected?

• Is the underlying population clearly defined?

• Who initiates reporting of the cases or events?

What are the components of an incidence

If this is well-defined, the surveillance is population-based.

Active, Population-based Surveillance for Rotavirus

Gastroenteritis in Chinese Children: Beijing Municipality and Gansu Province, China

Rate of admission per 10,000 population

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Individual cases or events?

• Specific etiologies (e.g., Vibrio cholerae) or syndromes (e.g., watery diarrhea)?

• Where are the cases or events being detected?

• Is the underlying population clearly defined?

• Who initiates reporting of the cases or events?

Passive surveillance:

reported

• Regular reporting of disease data by all institutions that see patients (or test

specimens) and are part of a reporting network

• No "active" search for cases; relies on the cooperation of health-care providers,

laboratories, hospitals, and clinics to report to a higher administrative level

Therefore, difficult to ensure completeness and timeliness

• Usually, every health facility is required to send a monthly (sometimes

weekly/daily) report of all cases on a standard form

• Less expensive than active surveillance and covers whole countries or provinces

National Dengue Surveillance in the Lao People ’ s Democratic Republic, 2006-2012

Dengue surveillance in the Lao

included within the indicator-based

National Surveillance System for

Notifiable Selected Diseases that

consists of passive weekly reports of

clinically suspected cases, on admission,

from all health-care facilities across the

country

WPSAR 2014;5(1):DOI.10.5365

Active surveillance: When detection of every case is important

• Involves visiting health facilities and reviewing medical records to

identify suspected cases

• When a case is found, surveillance staff investigate it, document

clinical and epidemiological data, arrange to send appropriate

laboratory specimens and report the information rapidly, according to national policy

• Usually used when a disease is targeted for eradication or elimination, when every possible case must be found and investigated

• Also used for outbreak investigations

Epidemiology of Infant Meningococcal Disease in the United States, 2006-2012

• Meningococcal disease

• Rare but serious in US

• Survivors often left with long-term

disabilities

• Vaccine available but expensive

• Is the burden of invasive

meningococcal disease high

enough that all infants should

receive meningococcal vaccine?

• Precise estimates of burden of

disease are needed

Pediatrics 2015; 135(2):DOI: 10.1542/peds.2014-2035

Objectives: By the end of this session,

you should be able to:

• Explain the difference between surveillance and planned studies

• Describe how surveillance is used in public health practice

• Describe the key elements of the public health surveillance cycle

• Describe the key features of the International Health Regulations

(active, passive, sentinel, etc.)

What kind of surveillance is being conducted?:

Some questions to guide you

• What is being detected by surveillance?

• Is the underlying population clearly defined: Population-based

• Who initiates reporting of the cases or events: Active vs passive

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