Title: Unit 4: Overview of Public Health Surveillance
1Unit 4 Overview of Public Health Surveillance
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2Warm Up Questions Instructions
- Take five minutes now to try the Unit 4 warm up
questions in your manual. - Please do not compare answers with other
participants. - Your answers will not be collected or graded.
- We will review your answers at the end of the
unit.
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3What You Will Learn
- By the end of this unit you should be able to
- describe the components of a surveillance system
- define sentinel surveillance, laboratory-based
surveillance and case definitions - define incidence and prevalence
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4What is Surveillance?
- Systematic collection of information on a
specific disease or other health-related event - Must occur on an ongoing basis with sufficient
accuracy and completeness for data analysis - Utilisation of information for disease prevention
and control
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5Information Loops
- A surveillance system is an information loop or
cycle that involves - healthcare providers
- public health agencies
- the public
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6Figure 4.1. Flow of Surveillance Data
Collection
Dissemination, Utilisation
Collation
Analysis and Interpretation
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7Surveillance Terms
- Universal case reporting a surveillance system
in which all cases of a disease are supposed to
be reported - Sentinel surveillance a surveillance system in
which reports are obtained from certain
facilities or populations - Laboratory-based reporting a surveillance
system in which the reports of cases come from
clinical laboratories instead of healthcare
practitioners or hospitals
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8Terms Related to Surveillance, Cont.
- Case definition the clinical and laboratory
characteristics that a patient must have to be
counted as a case for surveillance purposes - Prevalence the proportion of persons in a
population who have a disease or condition at a
given point in time - Incidence the number of persons who newly
develop a disease or condition within a specified
period of time
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9Terms Related to Surveillance, Cont.
- Passive surveillance a system in which data
generated without solicitation, intervention or
contact by the health agency carrying out the
surveillance. Other agencies initiate reporting. - Active surveillance the organization conducting
surveillance initiates procedures to obtain
reports
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10Table 4.1. Relationship Between Disease and Case
Definition
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11Additional Surveillance Terms
- Sensitivity the ability of a case definition or
laboratory test to predict true disease (a/(ac)) - Specificity the ability of a case definition or
laboratory test to predict absence of true
disease (d/(bd))
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12Additional Surveillance Terms, Cont.
- Positive predictive value proportion of persons
meeting a case definition, having a positive
test, that have true disease (a/(ab)) - Negative predictive value proportion of persons
not meeting a case definition, having a negative
test, that do not have true disease (d/(cd))
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13Past Approaches
- Duplication of efforts and resources
- Delays in reporting and identification of
outbreaks - Lack of dissemination and feedback to the local
level - Lack of integration of training and surveillance
activities
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14Common Problems with Past Surveillance Systems,
Cont.
- Limited evaluation of programmes
- Inadequate involvement of laboratories
- Incomplete reporting and lack of supervisory
support
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15Integrated Disease Surveillance (IDS)
- Integrates priority communicable disease
surveillance activities at the district level - Provides support for training and supervision
- Full-time district-level staff dedicated to
- monitoring health events in the community
- mobilising community action
- encouraging national assistance
- accessing regional resources
- Resources combined to collect information at each
level
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16IDS Goals
- Strengthen the capacity of countries to conduct
effective surveillance activities - Integrate multiple surveillance systems so that
forms, personnel and resources can be used more
efficiently and effectively - Improve the use of information for making
decisions - Improve the flow of surveillance information
between and within levels of the health system
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17IDS Goals, Cont.
- Improve laboratory capacity in identification of
pathogens and monitoring of drug sensitivity - Increase the involvement of clinicians in the
surveillance system - Emphasise community participation in detection of
and response to public health problems - Strengthen the involvement of laboratory
personnel in epidemiologic surveillance
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18Examples of Priority Communicable Diseases for IDS
- Epidemic-prone diseases
- Cholera
- Yellow fever
- Diseases targeted for eradication and elimination
- Polio
- Neonatal tetanus
- Other diseases of public health importance
- Malaria
- STIs
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19In Summary
- Surveillance is the collection of data relevant
to public health, which can then be analysed to
guide prevention and treatment programmes. - Sentinel surveillance involves the collection of
more detailed data from a smaller sample of sites - Laboratory-based reporting occurs when case
reports come from laboratories instead of health
facilities.
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20In Summary, Cont.
- Prevalence is the proportion or number of persons
in a certain population who have a particular
disease. - Incidence measures new infections during a
specific time period.
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21Warm Up Review
- Take a few minutes now to look back at your
answers to the warm up questions at the beginning
of the unit. - Make any changes you want to.
- We will discuss the questions and answers in a
few minutes.
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22Answers to Warm Up Questions
- 1. What is the name of the system that integrates
priority communicable disease activities at the
district level with support for training,
supervision and resources?
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23Answers to Warm Up Questions
- 1. What is the name of the system that integrates
priority communicable disease activities at the
district level with support for training,
supervision and resources? Integrated Disease
Surveillance
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24Answers to Warm Up Questions, Cont.
- 2. Which of the following terms indicates the
number or proportion of persons in a population
who have a disease at a given point in time? - a. sensitivity
- b. prevalence
- c. negative predictive value
- d. none of the above
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25Answers to Warm Up Questions, Cont.
- 2. Which of the following terms indicates the
number or proportion of persons in a population
who have a disease at a given point in time? - a. sensitivity
- b. prevalence
- c. negative predictive value
- d. none of the above
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26Answers to Warm Up Questions, Cont.
- 3. True or false? One-time cross-sectional
surveys are valid methods of HIV/AIDS
surveillance.
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27Answers to Warm Up Questions, Cont.
- 3. True or false? One-time cross-sectional
surveys are valid methods of HIV/AIDS
surveillance. False
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28Answers to Warm Up Questions, Cont.
- 4. Match the following terms with their
definitions -
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29Answers to Warm Up Questions, Cont.
- 4. Match the following terms with their
definitions -
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30Answers to Warm Up Questions, Cont.
- 5. Which of the following terms indicates the
number of persons who newly develop a disease
within a specified time period? - a. specificity
- b. positive predictive value
- c. incidence
- d. none of the above
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31Answers to Warm Up Questions, Cont.
- 5. Which of the following terms indicates the
number of persons who develop a disease within a
specified time period? - a. specificity
- b. positive predictive value
- c. incidence
- d. none of the above
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32Small Group Discussion Instructions
- Get into small groups to discuss these questions.
- Choose a speaker for your group who will report
back to the class.
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33Small Group Reports
- Select one member from your group to present your
answers. - Discuss with the rest of the class.
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34Case Study Instructions
- Try this case study individually.
- Well discuss the answers in class.
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35Case Study Review
- Follow along as we go over the case study in
class. - Discuss your answers with the rest of the class.
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36Questions, Process Check
- Do you have any questions on the information we
just covered? - Are you happy with how we worked on Unit 4?
- Do you want to try something different that will
help the group?
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