Islamic Republic of Afghanistan
Ministry of Public Health
Afghanistan National Public Health Institute ( ANPHI )
Surveillance / DEWS Directorate
Surveillance/Disease Early
Warning System (DEWS)
Naqeebullah Ziar MD, MPH
General Manager,
Disease Early Warning System (DEWS)
Afghanistan National Public Health Institute
Disease Early Warning System
Background of DEWS
• About eight years ago considerable time and effort
was spent to establish DEWS in all HFs.
• Passive surveillance systems working was
– ARI
– AWD
– Notifiable diseases e.g. CCHF and Cholera.
• Functional surveillance systems was
– AFP, Measles and NNT
• DEWS established mid December 2006 (8
provinces)
Afghanistan National Public Health Institute
Disease Early Warning System
Objectives of DEWS
• To reduce morbidity and mortality by early
detection, investigation, response and control
of outbreaks and other public health states and
conditions, throughout the country and
ultimately contribute to the economic stability
and development.
Afghanistan National Public Health Institute
Disease Early Warning System
DEWS action:
Detect, Confirm, Control
Record
infectious Chart &
assess
disease
infectious
cases
disease
Daily:
data
RESPOND
Weekly:
To Alerts
RESPOND
To Alerts
Investigate
suspected
outbreak
Take
action
to
control
All in full coordination of other stakeholders and partners
Afghanistan National Public Health Institute
Disease Early Warning System
Key Achievements
• Establishment of 313 sentinel sites in 34 provinces, and collecting
weekly data from the mentioned sites all over the country
• Since establishment of DEWS, 23660 specimens for different
disease collected and 70% were positive for different disease.
(Rotavirus in not included
• 2007
133 outbreaks detected and responded
• 2008
215 outbreaks detected and responded
• 2009
220 outbreaks detected and responded
• 2010
225 outbreaks detected and responded
• 2011
355 outbreaks detected and responded
• 2012
296 outbreaks detected and responded
• 2013
85 Outbreaks detected and responded (to date)
Afghanistan National Public Health Institute
Disease Early Warning System
Key Achievements cont….
• Below disease and causative agents detected/confirmed for the first
time inside the country;
• Hepatitis E, C.
• Diphtheria,
• Influenza B, Influenza A including A H1N1 virus,
• B. Pertussis,
• yersina pestis(causative agent for plague- Bubonic form),
• Rotavirus and
• Q-fever.
Afghanistan National Public Health Institute
Disease Early Warning System
Flow of DEWS Information
Routine weekly reports
Special ALERT reports whenever they
happen
CHCs
Hosp
DEWS
PHD –
HMIS CDC,
DEWS
BHCs
CHWs
CDC, EPI,
Malaria,
HMIS etc
Lab
Other
partners
Afghanistan National Public Health Institute
Disease Early Warning System
Kabul
Surveillance
Objectives
• Define public health surveillance
• Define active, passive, and syndromic
surveillance
• List some of the uses of surveillance
data
• Describe the components in the process
of public health surveillance, and give
examples of how to do each one
Afghanistan National Public Health Institute
Disease Early Warning System
Public Health Surveillance
Ongoing, systematic collection,
analysis, and interpretation of healthrelated data essential to the planning,
implementation, and evaluation of
public health practice, closely
integrated with the timely dissemination
of these data to those responsible for
prevention and control
Afghanistan National Public Health Institute
Disease Early Warning System
Public Health Surveillance
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Systematic
Ongoing
Collection
Analysis
Interpretation
Dissemination
Of Health data
Link to public health practice
Afghanistan National Public Health Institute
Disease Early Warning System
Prerequisites for
Public Health Surveillance
•
Organized health-care system
•
Classification system of disease
and injury
•
Measurement techniques
Afghanistan National Public Health Institute
Disease Early Warning System
Purposes of Public Health Surveillance
To portray the ongoing pattern of
health-related states and events,
to…
• Assess public health status
• Trigger public health action
• Define public health priorities
• Evaluate programs
Afghanistan National Public Health Institute
Disease Early Warning System
Some Uses of Public Health Surveillance
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Detect sudden changes in disease
occurrence and distribution
Monitor trends and patterns
Portray the natural history of a disease
Generate hypotheses, stimulate
research
Monitor changes in infectious agents
Detect changes in health practices
Evaluate control measures
Facilitate planning
Afghanistan National Public Health Institute
Disease Early Warning System
Public Health Surveillance
“Information for Action”
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Data Sources/Methods
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Notifiable diseases
Laboratory specimens
Vital records
Sentinel surveillance
Registries
Surveys
Administrative data systems
Other data sources
Afghanistan National Public Health Institute
Disease Early Warning System
Number of Notifiable Diseases –
International, Local
• WHO – 3 (plague, cholera, yellow
fever)
• United States – 15+
Afghanistan National Public Health Institute
Disease Early Warning System
Measles Case Definition
Clinical Case Definition
An illness characterized by all the following:
• A generalized rash lasting >3 days
• A temperature >101.0ºF (>38.3ºC)
• Cough, coryza, or conjunctivitis
Laboratory criteria for diagnosis
• Positive serologic test for measles immunoglobulin M antibody, or
• Significant rise in measles antibody level by any standard serologic
assay, or
• Isolation of measles virus from a clinical specimen
Case classification
Suspected: any febrile illness accompanied by rash
Probable: a case that meets the clinical case definition, has
noncontributory or no serologic or virologic testing, and is not
epidemiologically linked to a confirmed case
Confirmed: a case that is laboratory confirmed or that meets the
clinical case definition and is epidemiologically linked to a confirmed
case. A laboratory-confirmed case does not need to meet the clinical
case definition
Afghanistan National Public Health Institute
Disease Early Warning System
Types of Surveillance
Passive: Provider initiated
Active: Health-agency solicited
Afghanistan National Public Health Institute
Disease Early Warning System
Sentinel Surveillance
• Reporting of health events by health
professionals who are selected to
represent a geographic area or a
specific reporting group
• Can be active or passive surveillance
Afghanistan National Public Health Institute
Disease Early Warning System
Sentinel Surveillance:
Influenza-like Illness
as Proportion of Patients Seen
% of all patients
14
12
10
8
6
4
2
0
40
42
44
46
48
50
52
2
4
6
8
Week
Afghanistan National Public Health Institute
Disease Early Warning System
10
12
14
16
18
20
Syndromic Surveillance
• Syndromic surveillance – focuses on one
or constellation of symptoms rather than
diagnosed disease
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Data Tabulation
• Time
• Place
• Person
Afghanistan National Public Health Institute
Disease Early Warning System
Data Analysis by Place
• Where reported (usual method)
• Where exposure occurred (preferred)
• Allows prevention resources to be
targeted effectively
• Use of computers and spatial
mapping software allows for
sophisticated analysis
Afghanistan National Public Health Institute
Disease Early Warning System
Data Analysis by Person
• Demographics
– Age (most common), race, sex
– Occupation
• Risk factors, if collected
– e.g., Vaccination status
Afghanistan National Public Health Institute
Disease Early Warning System
Pertussis by Age Group, United States, 1998
2,400
2,100
Reported Cases
1,800
1,500
1,200
900
600
300
0
<1
1–4
5–9
10–14 15–19 20–29 30–39 40–49 50–59 >60
Age Group (Years)
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Analysis of Surveillance Data
• Descriptive – most common
• Analytic methods
– Time-series analyses to detect
aberrations
– Time-space clustering
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
What can account for an
apparent increase in cases?
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Afghanistan National Public Health Institute
Disease Early Warning System
What can account for an
apparent increase in cases?
• Change in reporting procedures / change in
surveillance system
• Change in case definition
• Improvements in diagnostic procedures
• Increased awareness
• Increased access to health care
• New physician, ICN, or clinic – may see more
referred cases, may make diagnosis more often,
or report more consistently
• Laboratory or diagnostic error
• Batch reporting
• Change in denominator
• True increase in incidence
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination…those
those who need to know
• Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Dissemination of Surveillance Data
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Health agency newsletter (e.g., MMWR)
Surveillance summaries / reports
Medical / epidemiologic journal articles
Press releases
Afghanistan National Public Health Institute
Disease Early Warning System
Process of Public Health Surveillance
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Data collection
Data tabulation
Data analysis
Data interpretation
Data dissemination
Link to action
Afghanistan National Public Health Institute
Disease Early Warning System
Link to Action
• Outbreak investigation
• Disease control
– Vaccination / prophylaxis
– Elimination of cause
– Interruption of transmission
• Development, targeting of programs
(education, risk reduction, etc.)
• Development of policies, regulations
Afghanistan National Public Health Institute
Disease Early Warning System
“Good surveillance does not
necessarily ensure the making of
the right decisions, but it
reduces the chances of [making
the] wrong ones.”
- Alex Langmuir, 1963
Afghanistan National Public Health Institute
Disease Early Warning System
Designing a Surveillance System
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Have clear objectives, and design to meet those
objectives.
Collect only the data needed to meet those
objectives.
Show those providing the reports how the health
department is using them to improve community
health status.
Value and build on personal relationships as well
as laws and rules.
Identify and remove barriers to rapid reporting of
those events that are put under surveillance.
Afghanistan National Public Health Institute
Disease Early Warning System
Many Decisions
• Objectives
• Data collection
– What to surveill
– Who will collect the data
– Who is the traget population
– When will the system operate
– Where to implement the system
– How:
• Active vs. passive
• What data elements
• How transmitted
Afghanistan National Public Health Institute
Disease Early Warning System
More Decisions
• Data Analysis
• Interpretation
• Dissemination
• Link to Action
• Resources
Afghanistan National Public Health Institute
Disease Early Warning System
“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 WH et al., Int. J of Epidemiology 1976; 5:29-37)
Afghanistan National Public Health Institute
Disease Early Warning System
Thank You
Afghanistan National Public Health Institute
Disease Early Warning System