Overview of Outbreak Investigations
Dr.suhaila 19-11-2014thu
Goals
• The goals of this presentation are to:
• Provide a general overview of the basic steps of disease outbreak
investigations
•
Describe factors that may contribute to a decision to investigate
Outbreaks: The basics
• Goals of an outbreak investigation:
• To identify the source of illness
• To guide public health intervention
• Ways to recognize an outbreak:
• Routine surveillance activities
• Reports from clinicians and laboratories
• Reports from affected individuals
Why investigate an outbreak?
• Characterize a public health problem
• Identify preventable risk factors
• Provide new research insights into disease
• Train health department staff in methods of public health investigations
and emergency response
Steps of an outbreak investigation
1. Verify the diagnosis and confirm the outbreak
2. Define a case and conduct case finding
3. Tabulate and orient data: time, place, person
4. Take immediate control measures
5. Formulate and test hypothesis
6. Plan and execute additional studies
7. Implement and evaluate control measures
8. Communicate findings
These steps may occur
simultaneously or be repeated as
new information is received.
Verify the diagnosis and confirm the outbreak
• Confirm laboratory testing
• Rule out misdiagnoses or laboratory error
1
Define a case and conduct case finding
• Develop a specific case definition using:
• Symptoms or laboratory results
• Time period
•
Location
•
Conduct surveillance using case definition
• Existing surveillance
• Active surveillance (e.g. review medical records)
•
Interview case-patients
Tabulate and orient data
Create line listing
1. Person
a. Who was infected?
b. What do the cases have in common?
2. Place
a. Where were they infected?
b. May be useful to draw a map
3. Time
• When were they infected?
• Create an epidemic curve
Take immediate control measures
• If an obvious source of the contamination is identified…institute control
measures immediately!
Formulate and test hypothesis
• Develop hypotheses
• literature reviews of previous outbreaks
• interviews of several case-patients
• Conduct an analytic study to test hypotheses
• Retrospective cohort study
• Case-control study
Plan and execute additional studies
Environmental sampling
• Collect appropriate samples
• Allow epidemiological data to guide testing
• If analytic study results are conclusive, don’t wait for positive
samples before implementing prevention
2
Implement and evaluate control measures
•
Prevent further exposure and future outbreaks by eliminating or treating
the source
•
Work with regulators, industry, and health educators to institute
measures
•
Create mechanism to evaluate both short- and long-term success
Communicate findings
•
Identify a single member of the investigation team to interact with
media and communicate progress and findings
•
Summarize investigation, make recommendations, and disseminate
report to all participants
Conclusions
•
The steps listed for an outbreak investigation comprise a brief
introduction and rough guide. Only by conducting investigations
repeatedly over an entire career will public health professionals truly
learn the methods of outbreak investigations.
•
Snow’s “
shoe leather epidemiology
” serves as a model of critical
thinking and public health action.
"Just for FUN
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