🦠microbiology review

Periods of disease

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Periods of disease refer to the distinct stages an infectious disease progresses through within a host. These stages include incubation, prodromal, illness, decline, and convalescence.

5 Must Know Facts For Your Next Test

  1. The incubation period is the time between exposure to the pathogen and the appearance of the first symptoms.
  2. During the prodromal period, early mild symptoms start to appear but are not yet specific or severe.
  3. The illness period is when disease symptoms are most severe and characteristic of the pathogen involved.
  4. In the decline period, symptoms begin to subside as the immune system or treatment starts to win against the pathogen.
  5. The convalescence period is when recovery occurs, and normal function is restored; however, some pathogens can still be transmissible.

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