public health surveillance

1. Dr Khyati Boriya

2. After studying this lesson you will be able to:After studying this lesson you will be able to:
•• Define public health surveillance and its mainDefine public health surveillance and its main
components (activities)components (activities)
•• List the main uses of surveillance dataList the main uses of surveillance data
•• Describe sources for data that can be used forDescribe sources for data that can be used for
public health surveillancepublic health surveillance
•• Describe the flow of information for reportableDescribe the flow of information for reportable
diseasesdiseases
2dr Khyati Boriya

3.  Ongoing, systematic collection, analysis,
and interpretation of health-related data
essential to the planning, implementation,
and evaluation of public health practice,
 with the timely dissemination of these data
to those responsible for prevention and
control.
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4. 1.1. Identify; define and measure the health problem of interest;Identify; define and measure the health problem of interest;
2.2. Collect and compile data about the problem (and if possible,Collect and compile data about the problem (and if possible,
factors that influence it)factors that influence it)
3.3. Analyze and interpret these dataAnalyze and interpret these data
4.4. Provide these data and their interpretation to thoseProvide these data and their interpretation to those
responsible for controlling the health problem andresponsible for controlling the health problem and
5.5. Monitor and periodically evaluate the usefulness and qualityMonitor and periodically evaluate the usefulness and quality
of surveillance to improve it for future use.of surveillance to improve it for future use.
N.BN.B
surveillance of a problemsurveillance of a problem doesdoes notnot include actions to control theinclude actions to control the
problem.problem.
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5. Information for Action
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6. Summaries,
Interpretations,
Recommendation
s
Report
s
Health
Agencie
s
Health
Care
Providers
Public
Analysis
Information Loop of Public Health SurveillanceInformation Loop of Public Health Surveillance
(involving health care providers, public health(involving health care providers, public health
agencies, and the public)agencies, and the public)
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7. The components of surveillance and
resulting public health action
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8. dr Khyati Boriya 8
Measurement
and recording
Transactional data
Data Management
•Quality checks
•Editing
Data preprocessing for a
specific purpose
(‘views’, ‘data marts’)
Analytical applications
Interpretation for associations,
trends, unusual patterns, signals
Public health response
Population of interestPopulation of interest
which generates eventswhich generates events
Surveillance System Components

9.  Public health surveillance provides andPublic health surveillance provides and
interprets data to facilitate theinterprets data to facilitate the
prevention and control of disease.prevention and control of disease.
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10.  Assess and monitor public health problemsAssess and monitor public health problems
 Estimate magnitude of the problemEstimate magnitude of the problem
 Useful in setting priorities to facilitate planningUseful in setting priorities to facilitate planning
 Portray the natural history of a diseasePortray the natural history of a disease
 Detect epidemics/define a problemDetect epidemics/define a problem
 Generate hypotheses, stimulate researchGenerate hypotheses, stimulate research
 Evaluate programs, control measuresEvaluate programs, control measures
 Detect changes in health practices & servicesDetect changes in health practices & services
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11. Year
ReportedCases
(Thousands) Vaccine
licensed
0
50
100
150
200
250
300
350
400
450
500
1963 1968 1973 1978 1983 1988 1993 1998
MEASLES — by year, United
States, 1983–1998
0
5
10
15
20
25
30
Year
1983 1988 1993 1998
ReportedCases
(Thousands)
Evaluate control measures of MEASLESEvaluate control measures of MEASLES
United States, 1963-1998
20
10
11dr Khyati Boriya

12. Selecting a Health Problem for Surveillance:
 Conducting surveillance for a health problem
consumes time and resources.
 It is important to select and prioritizing healthIt is important to select and prioritizing health
problems for surveillanceproblems for surveillance
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13. Public health importance of the problem:Public health importance of the problem:
 incidence, prevalence,incidence, prevalence,
 severity, sequela, disabilities,severity, sequela, disabilities,
 mortality caused by the problem,mortality caused by the problem,
 socioeconomic impact,socioeconomic impact,
 communicability,communicability,
 potential for an outbreak,potential for an outbreak,
 public perception and concern, andpublic perception and concern, and
 international requirements.international requirements.
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14. Ability to prevent, control, or treat the healthAbility to prevent, control, or treat the health
problem:problem:
 preventability andpreventability and
 Availability of control measures and treatment.Availability of control measures and treatment.
Capacity of health system to implement controlCapacity of health system to implement control
measures for the health problem:measures for the health problem:
 Immediate responseImmediate response
 availability of resourcesavailability of resources
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15. Three main sources:
 Individual Persons
 Health-care providers, facilities, and records
— Physician offices
— Hospitals
— Outpatient departments
— Emergency departments
— Inpatient settings
— Laboratories
3. Environmental conditions
— Air
— Water
— Animal vectors
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16. 1. Environmental monitoring
2. Surveys
3. Notifications
4. Registries.
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17.  Surveys, uses a “structured and systematic
gathering of information” from a sample of “a
population of interest to describe the population in
quantitative terms.”
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18.  A notification is the reporting of certain
diseases or other health-related conditions by a
specific group, as specified by law, regulation,
or agreement.
 Notifications are typically made to the state or
local health agency.
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19.  ReregisteryReregistery is a method for documenting oris a method for documenting or
tracking events or persons over time.tracking events or persons over time.
Examples:Examples:
 Registries of vital events (birth and deathRegistries of vital events (birth and death
certificates) are required by law and containcertificates) are required by law and contain
important health-related information.important health-related information.
 A disease registry (e.g., a cancer registry) tracks aA disease registry (e.g., a cancer registry) tracks a
person with disease over time and usuallyperson with disease over time and usually
includes diagnostic, treatment, and outcomeincludes diagnostic, treatment, and outcome
information.information.
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20.  Vital events, births, deaths, marriages, divorce,...
 Morbidity data; infections diseases, non-
communicable diseases, birth defects, injuries,...
 Mortality data
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21.  Analyzing by time
 Analyzing by place
 Analyzing by person
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22.  Observed increases or decreases in diseaseObserved increases or decreases in disease
incidence or prevalence might be an artifact.incidence or prevalence might be an artifact.
 Common causes of artifactual (not true) changeCommon causes of artifactual (not true) change
in disease occurrence are:in disease occurrence are:
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23. • Changes in local reporting procedures or policies (e.g., aChanges in local reporting procedures or policies (e.g., a
change from passive to active surveillance).change from passive to active surveillance).
• Changes in case definition (e.g., AIDS in 1993).Changes in case definition (e.g., AIDS in 1993).
• Increased health-seeking behavior (e.g., media publicityIncreased health-seeking behavior (e.g., media publicity
prompts persons with symptoms to seek medical care).prompts persons with symptoms to seek medical care).
• Increase in diagnosis.Increase in diagnosis.
• New laboratory test or diagnostic procedure.New laboratory test or diagnostic procedure.
• Increased physician awareness of the condition, or a newIncreased physician awareness of the condition, or a new
physician is in town.physician is in town.
• Increase in reporting (i.e., improved awareness ofIncrease in reporting (i.e., improved awareness of
reporting).reporting).
• Outbreak of similar disease, misdiagnosed as disease ofOutbreak of similar disease, misdiagnosed as disease of
interest.interest.
• Laboratory error.Laboratory error.
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24. Data and interpretations should be sent to:Data and interpretations should be sent to:
•those who provided reports or other data (e.g.,those who provided reports or other data (e.g.,
health-care providers and laboratory directors).health-care providers and laboratory directors).
They should also be sent to those who use them forThey should also be sent to those who use them for
•planning orplanning or
•managing control programs,managing control programs,
•Administrative purposes,Administrative purposes,
•or other health-related decision-making.or other health-related decision-making.
24dr Khyati Boriya

25. 1.1. Passive (Routine reporting system)Passive (Routine reporting system)
Hospitals, health centers, health facilities.Hospitals, health centers, health facilities.
Reporting is governed by existing local rules.Reporting is governed by existing local rules.
Advantages:Advantages:
 Inexpensive.Inexpensive.
 Standardized.Standardized.
 Good for monitoring large numbers of typical healthGood for monitoring large numbers of typical health
eventsevents
Disadvantages:Disadvantages:
 Under-reporting is a problemUnder-reporting is a problem
 Incomplete dataIncomplete data
 Busy doctors & nursesBusy doctors & nurses
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26. 2-Active (Sentinel reporting system):2-Active (Sentinel reporting system):
Collection of data on a specific disease for a relativelyCollection of data on a specific disease for a relatively
limited period of time.limited period of time.
By selected health units, certain physicians,…By selected health units, certain physicians,…
Advantages:Advantages:
 More consistent pictures.More consistent pictures.
 Motivated.Motivated.
Disadvantages:Disadvantages:
 Not representativeNot representative
 Active surveillance is relatively expensive practice.Active surveillance is relatively expensive practice.
 It is usually limited to disease elimination programs andIt is usually limited to disease elimination programs and
to short-term intensive investigation and controlto short-term intensive investigation and control
activities, or to seasonal problems, (e.g. Influenza,activities, or to seasonal problems, (e.g. Influenza,
arboviruses).arboviruses).
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