Download Outbreak Detection and Investigation

Outbreak Detection and Investigation
1. A key public health function
2. Multi-disciplinary, but the epidemiologic
component/approach is central
3. Requires a thoughtful, systematic approach
4. Requires well-trained investigators
5. Often poses substantial threat of economic harm
and legal liability to individuals and companies
6. Typically occurs under a spotlight and requires
excellent communication with decision-makers,
the media, and the general public
Reasons why Outbreak Detection and Investigation
are Important Public Health Functions
1. Terminate the outbreak/prevent new cases
2. Prevent future outbreaks
3. Gain knowledge about a disease, whether
“new” or “old”
4. Reassure the public
5. Teach/learn epidemiology
Outbreak Detection and Investigation
1. The disease may be “new” or “old”
2. The causative agent may be known or unknown
at the time of the investigation
3. The etiology of the disease may be an infectious
agent, a chemical toxin, a nutritional deficiency,
some other type of agent, or a combination of
agents
Components of an Outbreak Investigation
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Case Definition
Confirmation of Cases
Case Finding
Establish the Baseline/Determine if there is an Outbreak
Describe Epidemiologic Features (time, place, person)
Hypothesis Generation
Hypothesis Testing
Implementation of Control Measures
Effective Communication
Collection of Appropriate Specimens (environmental
and clinical)
• Establish the Etiology
How do Epidemiologic Studies Done as Part of an
Outbreak Investigation Differ from “Normal”
Epidemiologic Studies?
1. Time/political pressure; speed is important
2. Primary purpose typically is to implicate a source rather
than give a precise estimate of a risk ratio
3. Underlying “true” risk ratio is somewhere between
enormous and infinite
4. Sample size/power calculations are rarely,
if ever done
How Do Epidemiologists Learn About the
Existence of Outbreaks?
• Patients/Families (e.g. Lyme disease)
• Clinicians (e.g. Legionnaires’, TSS, AIDS)
• Laboratorians
• Surveillance
• Media Reports (SARS)