Epidemiology in outbreak

definition of outbreak by CDC

• epidemic limited to localised increase in the incidence of disease
• Epidemic Disease Occurrence - Level of disease

what to do when to investigate an outbreak

• Steps of an Outbreak Investigation

1. Prepare for field work
2. Establish the existence of an outbreak
3. Verify the diagnosis
4. Construct a working case definition
5. Find cases systematically and record information
6. Perform descriptive epidemiology
7. Develop hypotheses
8. Evaluate hypotheses epidemiologically
9. As necessary, reconsider, refine, and re-evaluate hypotheses
10. Compare and reconcile with laboratory and/or environmental studies
11. Implement control and prevention measures
12. Initiate or maintain surveillance
13. Communicate findings

second attack rate

• proportion of individuals who are exposed to an infectious agent who become ill

[math]\displaystyle{ SAR=\frac{number of becoming ill}{number of exposed} }[/math]