it is most important topic

2. Steps of an Outbreak
Investigation
By
MRS. J.ANUSHA
ASSISTANT
PROFESSOR,
NARAYANA
COLLEEGE OF
NURSING,
NELLORE

3. 10 steps are there
in an Out break
investigation

4. Step 1: Prepare for
field work

5. The preparations can be grouped
into two broad categories:
(a) scientific and investigative
issues
(b) management and operational
issues

6. a) scientific and investigative issues
1. investigator must have
appropriate scientific
knowledge about the disease
and about field investigation
2. Investigator should have a plan
of action, necessary supplies
and equipment, the proper
laboratory material and should
know the proper collection,
storage, and transportation
techniques for collected

7. b) management and operational
issues
An investigator must be a
good manager also, because
most investigations are
conducted by a team rather
than just one individual. The
team members must be
selected before departure and
they should know their
expected roles and
responsibilities in the field.

8. Step 2: Establish the
existence of an outbreak

9. To establish the existence of an outbreak, the observed
number of cases is compared with the expected number
for a certain place or time period.
Even if the current number of reported cases exceeds
the expected number, the excess may not necessarily
indicate an outbreak. Therefore, look for the various
factors that may increase the number of cases such as:
Seasonal variation, Notification variation, Sudden change
in population size , Diagnostic variation.

10. Step 3: Verify the diagnosis/ ensure
proper diagnosis of reported cases

11. For verification of diagnosis:
Investigator should talk to health workers first, then review the
clinical findings and laboratory results.
If laboratory diagnosis in not made or there is any doubt in diagnosis,
team member may collect a sufficient number of appropriate specimens
for further confirmation of disease.
It is useful to visit one or more patients with the disease, talking
directly with some patients can give a better understanding of the
clinical feature.
Summarize the clinical findings with frequency distribution (number
of cases).

12. Step 4: Define and identify
cases

13. A case definition is constructed for the identification of
cases. It is a standard set of criteria for deciding whether
an individual should be classified as having the health
condition of interest.
A case definition includes clinical criteria (signs and
symptoms) and restrictions by time, place, and person.
The criteria must be applied consistently to all persons
under investigation.
A case classified as probable usually has typical clinical
features of the disease without laboratory confirmation.

14. Step 5: Perform descriptive
epidemiology

15. In an outbreak situation, cases that prompt the concern are
often only a small and do not represent the total number of
cases.
All the cases should be counted as reported by either
passive surveillance or reported by active surveillance.
The details of the patient includes:
Identifying information
Demographic information
Clinical information includes signs and symptoms.
Risk factor information.
 Reporter information

16. The next step after identifying and gathering basic
information about the persons with the disease is to
systematically describe some of the key
characteristics of those persons in terms of time,
place, and person. This is called descriptive
epidemiology.

17. Step 6: Develop hypotheses

18. The descriptive epidemiology may provide useful clues
that can be turned into hypotheses. In an outbreak
context, hypotheses are generated in a variety of ways.
First, consider what is known about the disease itself:
What is the agent's usual reservoir? How is it usually
transmitted? What vehicles are commonly implicated?
What are the known risk factors?

19. Step 7: Evaluate
hypotheses

20. After a hypothesis that might explain an
outbreak has been developed, the next step is to
evaluate the plausibility of that hypothesis.
Typically, hypotheses in a field investigation are
evaluated using a combination of
environmental evidence, laboratory science,
and epidemiology. From an epidemiologic point
of view, hypothesis is evaluated in one of two
ways: either by comparing the hypotheses with
the established facts or by using analytic
epidemiology to quantify relationships and
assess the role of chance.

21. Step8. Communicate
findings

22. The final task is to summarize the
investigation, its findings, and its outcome
in a report, and to communicate this
report in an effective manner. An oral
briefing for local authorities and a written
report that follows the usual scientific
format of introduction, background,
methods, results, discussion, and
recommendations should be send to
concerned authority.

23. Step 9: Implement control and
prevention measures

24. In most outbreak
investigations, the primary
goal is control of the
outbreak and prevention of
additional cases. In practice
control and prevention
activities are implemented
as early as possible.

25. Step10: Follow up
recommendations/
maintain surveillance

26. Once control and prevention measures have
been implemented, outbreak situation
should be monitored. Active surveillance
should be continued as it is essential for:
Deciding if outbreak is over and for this
surveillance may be continued for at least
two incubation periods of concerned disease
following onset in the last case
Documenting effectiveness of control
measures

27. Disease surveillance, outbreak investigation and
response in India
Integrated Disease Surveillance Programme, National Centre
for Disease Control working under Directorate General of
Health Services, Ministry of Health and Family Welfare
(MoHFW), Government of India (GOI) is implementing and
monitoring the disease surveillance in the country by
establishing a decentralized state based surveillance
system (laboratory based and IT enabled) for epidemic
prone diseases to detect the early warning signals, so that
timely and effective public health actions can be initiated in
response to health challenges in the country at the districts,
state and national level.

28. The Integrated Health Information Platform
(IHIP), a web-enabled near-real-time
electronic information system is also
incorporated for disease surveillance and for
managing disease outbreaks since November
2018 in selected districts of 7 States
(Karnataka, Andhra Pradesh, Himachal
Pradesh, Odisha, Uttar Pradesh, Telangana &
Kerala) in its first phase.