Applications on Public Health Surveillance

Applications on:
Public Health
Surveillance
By:
Donia Attia Sadoun
Alaa Abdel Mohsen Ismail
1
Under supervision of:
Prof. Dr. Mona Aboserea

Introduction
• Public health surveillance is:
“The ongoing, systematic collection,
analysis, and interpretation of health-
related data essential to planning,
implementation, and evaluation of
public health practice, closely integrated
with the timely dissemination of these
data to those responsible for prevention
and control”. (CDC)
4
Defining the
problem
Data
collection
Data analysis
Data
Interpretation
Data
Dissemination
Linked to
action
Evaluate the
system
Steps of public health
surveillance system
process

MCQ
QUESTIONS
Choose ALL
correct answers for
each question:
5

1. Public health
surveillance includes
which activities?
• Data collection.
• Data analysis.
• Data interpretation.
• Data dissemination.
• Disease control.
Answers: A, B, C and D.
Explanation:
o The term public health
surveillance includes data
collection, analysis, interpretation,
and dissemination to help guide
health officials and programs in
directing and conducting disease
control and prevention activities.
o However, surveillance does not
include control or prevention
activities themselves.
6

2. Current public
health surveillance
targets which of the
following?
• Chronic diseases.
• Communicable diseases.
• Health-related behaviors.
• Occupational hazards.
• Presence of viruses in
mosquitoes.
Answers: A, B, C, D and E.
Explanation:
o Current public health surveillance targets
health-related conditions among humans,
including:
1. Chronic diseases (e.g., cancer).
2. Communicable diseases (e.g., those
on the notifiable disease list).
3. Health-related behaviors and
occupationally related conditions
(e.g., black lung disease and other
pneumoconiosis).
4. Indicators of disease potential (e.g.,
such diseases among animals as
rabies).
5. Presence of an infectious agent
among animals or insects (e.g., West
Nile virus among mosquitoes).
7

3. Public health
surveillance can be
described primarily as
which of the following?
• A method to monitor occurrences
of public health problems.
• A program to control disease
outbreaks.
• A system for collecting health-
related information.
• A system for monitoring persons
who have been exposed to a
communicable disease.
Answer: A
Explanation:
o Public health surveillance can be thought
of as one of the methods that a
community has available to monitor
the health among its population by
detecting problems, communicating
alerts as needed, guiding the appropriate
response, and evaluating the effect of the
response.
o Surveillance should not be confused with
medical surveillance, which is
monitoring of exposed persons to detect
early evidence of disease.
o Public health surveillance is the
continued watchfulness for public
health problems; it is not a data-
collection system.
8

4. Public health
surveillance is only
conducted by public
health agencies.
• True.
• False.
Answer: B (False).
Explanation:
o The practice of surveillance is not
limited to public health agencies.
Hospitals, nursing homes, the
military, and other institutions have
long conducted surveillance of their
populations.
9

5. Common uses and
applications of public health
surveillance include which of
the following?
• Detecting individual persons with malaria
so that they can receive prompt and
appropriate treatment.
• Helping public health officials decide how
to allocate their disease control resources.
• Identifying changes over time in the
proportion of children with elevated blood
lead levels in a community.
• Documenting changes in the incidence of
varicella (chickenpox), if any, after a law
requiring varicella vaccination took effect.
Answers: A, B, C and D.
Explanation:
o Among the uses of surveillance are:
1. Detecting individual cases of diseases of
public health importance (e.g., malaria).
2. Supporting planning (e.g., priority
setting).
3. Monitoring trends and patterns of
health-related conditions (e.g., elevated
blood lead levels).
4. Supporting evaluation of prevention
and control measures (e.g., a vaccination
requirement).
10

6. Data collected through
which of the following
methods is commonly used
for surveillance?
• Vital registration.
• Randomized clinical
trials.
• Disease notifications.
• Population surveys.
Answers: A, C and D.
Explanation:
o Data collected through vital
registration, disease notifications, and
population surveys are commonly used
for surveillance of health-related
problems.
o Data from randomized clinical trials
typically cover only a specially selected
population and are used to answer
specific questions about the effectiveness
of a particular treatment. They are not
useful for surveillance.
11

7. Health-care providers might
be important sources of
surveillance data used by public
health officials, and they should
receive feedback to close the
surveillance loop as a courtesy;
however, the results almost
never have any relevance to
patient care provided by those
health-care providers.
• True.
• False.
 Answer: B (False).
 Explanation:
o One of the important uses of surveillance
data and one of the key reasons to close the
surveillance loop by disseminating
surveillance data back to health-care
providers, is to provide clinically relevant
information about disease occurrence,
trends, and patterns.
o For example, health departments alert
clinicians to the presence of new diseases
(e.g., severe acute respiratory syndrome
[SARS]) and provide information so that
clinicians can make diagnoses. Health
departments also advise clinicians about
changing patterns of antibiotic resistance so
that clinicians can choose the right treatment
regimen.
12

8. Vital statistics are
important sources of
data on which of the
following?
• Morbidity.
• Mortality.
• Health-related behaviors.
• Injury and disability.
• Outpatient health-care usage.
Answer: B.
Explanation:
o Vital statistics refer to data on birth,
death, marriage, and divorce.
o Therefore, vital statistics are the
primary source of data on
mortality, but not on morbidity
(illness), behaviors, injury (other
than fatal injuries), and health-
care usage.
13

9. Vital statistics provide
an archive of certain
health data. These data do
not become surveillance
data until they are
analyzed, interpreted, and
disseminated with the
intent of influencing
public health decision-
making or action.
• True.
• False.
Answer: A (True).
Explanation:
o Vital statistics are usually thought of as an
archive of births, deaths, marriages, and
divorces. Vital statistics offices in health
departments typically are not linked to disease
prevention and control activities.
o However, surveillance for certain health
problems might rely on vital statistics as its
primary source of data. When these data
undergo timely and systematic analysis,
interpretation, and dissemination with the
intent of influencing public health decision-
making and action, they become surveillance
data.
14

10. Notifiable disease
surveillance usually focuses
on morbidity from the
diseases on the list and does
not cover mortality from
those diseases.
• True.
• False.
Answer: B (False).
Explanation:
o Notifiable disease surveillance
targets occurrence or death
from any of the diseases on the
list.
15

11. Evaluating and
improving surveillance
should address which of the
following?
• Purpose and objectives of
surveillance.
• Resources needed to conduct
surveillance.
• Effectiveness of measures for
controlling the disease under
surveillance.
• Presence of characteristics of
well-conducted surveillance.
 Answers: A, B and D.
 Explanation:
o Evaluation of surveillance for a health-related
problem should include:
1. Review of the purpose and objectives of
surveillance.
2. The resources needed to conduct
surveillance for the problem.
3. Whether the characteristics of well-
conducted surveillance are present.
o Because surveillance does not have direct
responsibility for the control of the health
problem, this is not part of evaluating a
surveillance system.
16

12. Criteria for prioritizing
health problems for
surveillance include which
of the following?
• Incidence of the problem.
• Public concern about the
problem.
• Number of previous
studies of the problem.
• Social and economic
impact of the problem.
Answers: A, B and D.
Explanation:
o The incidence of, public concern
about, and social and economic
impact of a health problem are all
important in assessing its
suitability for surveillance.
o Although previous studies of the
problem might have helped to
characterize its natural history,
cause, and impact, the number of
such studies is not used as a
criterion for prioritization.
17

13. Underreporting is not a
problem for detecting
outbreaks of notifiable
diseases because the
proportion of cases
reported tends to remain
relatively stable over time.
• True.
• False.
 Explanation:
o Underreporting is a serious problem for
surveillance that relies on notifications.
o Because the notifiable disease surveillance is
supposed to identify individual cases of disease
of public health importance, underreporting of
even a single case of, for example, hepatitis A
in a food handler, can result in an outbreak that
should have been prevented.
o Similarly, if a limited number of cases are
reported at all, even outbreaks can be missed.
18

14. The case definition used
for surveillance of a health
problem should be the
same as the case definition
used for clinical (treatment)
purposes.
• True.
• False.
 Explanation:
o A case definition for surveillance should be
clear, understandable, acceptable, and
implementable by those who are required to
apply it.
o However, it need not use the same criteria
that are used for clinical purposes.
o For example, health-care providers might treat
patients on the basis of clinical features without
laboratory confirmation, whereas a surveillance
case definition might require confirmation, or
vice versa.
19

15. Initiating surveillance for a public health problem or
adding a disease to the notifiable disease list is justified for
which of the following reasons?
• If it is a communicable disease with a high case-fatality rate.
• If the problem is new and systematically collected data are
needed to characterize the disease and its impact on the
public.
• If a program at CDC has recommended its addition to better
understand national trends and patterns.
• To guide, monitor, and evaluate programs to prevent or
control the problem.
20

 Answers: B and D.
 Explanation:
o Initiating surveillance for a health-related problem can be justified for multiple reasons.
These reasons include:
1. If a disease is new and surveillance is the most effective means for collecting
information on cases to learn more about its clinical and epidemiologic features
(e.g., SARS).
2. If a new prevention or control measure is about to be implemented and
surveillance is the most effective means for assessing its impact (e.g., varicella
vaccination regulations).
3. If surveillance is needed to guide, monitor, and evaluate prevention or control
measures.
o Surveillance is more difficult to justify if a disease does not occur locally, even if it is a
communicable disease with a high case fatality rate (e.g., Ebola or Marburg virus infection),
or simply because CDC requests it (without funding).
21

16. A state health department decides to strengthen
its notifiable disease reporting. The one best action
to take is to …
• allow reporting through use of the Internet.
• require more disease-specific forms from local health
departments.
• ensure that all persons with a responsibility to report
understand the requirements and reasons for reporting and
how reports will be used.
• reduce the number of diseases on the list.
22

23
 Answers: C.
 Explanation:
o The most important way to improve notifiable disease surveillance is to ensure that everyone
who is supposed to report knows:
1. that they are supposed to report,
2. what to report (i.e., which diseases are on the list), and
3. how, to whom, and how quickly to report.
o In addition, they will be more likely to report if they know that the health department is doing
something with the reports.
o No data are available that demonstrate that reporting through the Internet improves
reporting; in fact, for certain health-care providers, reporting might involve extra work.
o Requiring more disease-specific forms tends to reduce reporting, because it requires more
time and effort for those reporting.
o Reducing the number of diseases on the list might be part of a strategy to improve
reporting, but it is not the most important way to do so.

Case No. 1
A 77-year-old female with a history of
hypertension and hyperlipidemia who
presented as a transfer to our hospital facility
with worsening fevers, cough, and respiratory
distress. Chest X-rays revealed bilateral
infiltrates worse at the lung bases and CT
scan of the chest showed bilateral ground-
glass opacities consistent with COVID-19.
 What is the case definition of COVID-19?
26

Answer Of Case No. 1
27
‫هذه‬
‫الصورة‬
‫بواسطة‬
‫كاتب‬
‫غير‬
‫معروف‬
‫مرخصة‬
‫باالسم‬ CC BY-SA

Clinical Criteria
of COVID-19:
1. Acute onset of fever AND cough; OR
2. Acute onset of ANY THREE OR MORE of
the following signs or symptoms:
• Fever/Cough/General weakness.
• Fatigue/Headache/Myalgia/Sore throat.
• Coryza/Dyspnea/Anorexia.
• Nausea/Vomiting/Diarrhea/Altered
mental status.
28

Epidemiological Criteria of COVID-
19:
1. Residing or working in an area with high risk of transmission: for example,
closed residential settings, humanitarian settings such as camp and camp-like
settings for displaced persons, any time within the 14 days of symptom onset
OR
2. Residing in or travel to an area with community transmission anytime within
the 14 days of symptom onset OR
3. Working in a healthcare setting anytime within the 14 days prior to symptom
onset.
29

Case Definition
of COVID-19:
1. Suspected COVID-19 case
2. Probable COVID-19 case
3. Confirmed COVID-19 case
30

Case Definition
of COVID-19:
1. Suspected COVID-19 case
(two suspected case definitions A or B)
A. A person who meets the clinical and
epidemiological criteria.
B. A patient with severe acute respiratory
illness (SARI: acute respiratory infection
with history of fever of ≥ 38 C°, and cough
with onset within the last 10 days and who
requires hospitalization).
31

Case Definition
of COVID-19:
A. Patient who meets clinical criteria AND is a
contact of a probable or confirmed case,
or epidemiologically linked to a cluster
with at least one confirmed case OR
B. A suspected case with chest imaging
showing findings suggestive of COVID-19
disease OR
32

Case Definition
of COVID-19:
C. A person with recent onset of anosmia (loss
of smell) or ageusia (loss of taste) in the
absence of any other identified cause OR
D. Unexplained death in an adult with
respiratory distress who was a contact of a
probable or confirmed case or
epidemiologically linked to a cluster with
at least one confirmed case.
33

Case Definition
of COVID-19:
3. Confirmed COVID-19 case
A person with laboratory confirmation
(PCR with deep nasal swab is the
current test of choice) of COVID-19
infection, irrespective of clinical signs
and symptoms.
34

Case No. 2
• You are responsible for an infection control
unit. In the morning, the nurse told you that
there are 3 cases of fever, chest pain,
reproductive cough and dyspnea. Two days
before, there were 3 cases. You decided to trace
this infection in the hospital.
• The provisional diagnosis is pneumonia for
differential diagnosis.
1. How could you trace these infections?
2. Why would you like to trace such
infection?
3. What are the steps you should follow?
36

Answers Of Case No. 2
37
‫هذه‬
‫الصورة‬
‫بواسطة‬
‫كاتب‬
‫غير‬
‫معروف‬
‫مرخصة‬

2.1 How
could you
trace these
infections?
Active Surveillance is required.
38

2.2 Why would you
like to trace such
infection?
a) To calculate incidence of hospital
acquired infections.
b) To assess the severity of infection
(hospital stay, economic cost).
c) To evaluate the infection control
measures.
d) To detect causes of increased
infection through orientation of
data by time, place and person.
e) To plan for better infection
control measures.
39

2.3 What are the
steps you should
follow?
Put
Put case definition of
pneumonia.
Decide
Decide the population
under surveillance.
Formulat
e
Formulate surveillance
cycle.
40

A. Case definition of pneumonia:
1. Suspected: Clinical picture and suspected X-ray.
2. Probable: Imaging showing specific character of bacterial or
viral pneumonia.
3. Confirmed: Isolation of the organism from blood or
sputum.
41

2.3 What are the
steps you should
follow?
Put
pneumonia.
Decide
under surveillance.
Formulat
e
cycle.
42

B. Decide population under
surveillance:
Hospital based surveillance
includes:
 All patients in intensive care
units.
 Patients in inpatient
departments.
43

2.3 What are the
steps you should
follow?
Put
pneumonia.
Decide
under surveillance.
Formulat
e
cycle.
44

C. Surveillance
Cycle
1. Data
collection
2. Data
Analysis
3. Data
interpretation
4. Data
Dissemination
5. Link to
action
6. Evaluation
45

1. Data
Collection:
 The objective of
surveillance is:
1. To calculate incidence of
pneumonia.
2. To detect cause of
increased incidence.
3. Put infection control plan.
 Collect data from reported
cases and hospital record and
active search of cases.
 Assessment of infection
control measures and health
care workers' practice.
46

2. Data
Analysis:
 Line list of cases including
demographic and clinical
information, risk factors, lab
results……etc.
 Descriptive epidemiology:
1. Person: age, sex .
2. Place: intensive care units,
inpatient units.
3. Time: weekly report.
47

3. Data
Interpretatio
n:
 Comment if there is increased
rate of infection and put
hypothesis about the cause.
 There is increased risk of
pneumonia among patients in
intensive care units, the most
probable cause is defective
infection control measures.
48

4. Data
Disseminatio
n:
 Formulate a report describing
the current situation and
proper corrective action
needed.
 Disseminate data to the
hospital manager.
49

5. Link to
Action:
 Take action needed
through:
1. Infection control plan.
2. Training of health care
workers.
50

6.
Evaluation:
 To promote the best use of
public health resources by
ensuring that this important
problem are under
surveillance and that the
surveillance system operates
efficiently.
51

Case No. 3
Chlamydia Infection
52

Case No. 3
A researcher is urging the state health
department to add chlamydial infections to
the state’s list of reportable diseases.
1. What are the arguments for this
action?
2. What are the arguments against this
action?
3. What alternative methods of
surveillance for chlamydial infection
might you propose?
53

Answers Of Case No. 3
54
‫هذه‬
‫الصورة‬
‫بواسطة‬
‫كاتب‬
‫غير‬
‫معروف‬
‫مرخصة‬

3.1 What are the arguments for this
action?
a) Surveillance will provide an estimate
of the true prevalence of this
important but often overlooked
condition.
b) Infection is treatable, and
transmission is preventable.
c) Untreated, chlamydial infection is a
major cause of pelvic inflammatory
disease and infertility.
55

3.2 What are the arguments against this
action?
a) Clinicians feel the list is already too long.
b) Clinicians may feel they should only be
required to report communicable diseases
with high morbidity and/or mortality
that will lead to immediate intervention by
the health department.
c) Adding chlamydia to the list will not lead
to better diagnosis and treatment, since
many infections are asymptomatic.
56

3.3 What alternative
methods of surveillance for
chlamydial infection might
you propose?
a) Enroll interested and
appropriate health care
providers (e.g., obs/gyn) and
clinics in a sentinel
surveillance system.
b) Laboratory-based surveillance.
57

SUMMARY
Public Health Surveillance is an epidemiological tool that
necessitates continuous collection and analysis of health events by
professional epidemiologists.
The practice of surveillance is not limited to public health
agencies.
Uses of surveillance include detecting individual cases of diseases
of public health importance, supporting planning, monitoring
trends and patterns of health-related conditions and supporting
evaluation of prevention and control measures.
Surveillance cycle includes defining the problem, data collection,
data analysis, data interpretation, data dissemination, linked to
action and evaluation of the system.
59

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