Epidemiology in outbreak

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2021年4月22日 (木) 15:02時点におけるVaccipedia.admin (トーク | 投稿記録)による版
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definition of outbreak by CDC

what to do when to investigate an outbreak

  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 (SAR)

  • 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]

reproduction number

basic reproduction number

  • average number of secondary cases caused by a single primary case in a fully susceptible population

effective reproduction number

  • actual number of secondary cases per single primary case

time course

  • incubation period
    • followed by symptomatic p.
  • symptomatic p.


  • latent (pre-infectious) p.
    • followed by infectious p.
  • infectious p.


  • serial interval
    • time from illness onset of primary case to illness onset of secondary case caused by primary case
  • generation time
    • time from infection of primary case to /u>infection of secondary case caused by primary case

SIR model

  • S = susceptible
  • I = infected
  • R = recovered
  • β = transmission coefficient (S→I)
  • γ = recovery rate (I→R)