Spread of Influenza Definitions

Summary of the Geographic Spread of Influenza — This level does not measure the severity of influenza activity.  States report geographic spread of influenza activity as no activity, sporadic, local, regional, or widespread. These levels are defined as follows:

  • No Activity: No laboratory-confirmed cases of influenza and no reported increase in the number of cases of ILI.
  • Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.
  • Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
  • Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions.
  • Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.

Back to the Influenza page | Back to Influenza/RSV Reports page

Example:

weekly status of activity level in arizona