Metrics

OutbreakNet Enhanced sites incorporate performance metrics and model practices into their capacity building plans. OutbreakNet Enhanced performance metrics are a subset of FoodCORE and Council to Improve Foodborne Outbreak Response (CIFOR)external icon measures used to document the burden, timeliness, and completeness of enteric disease surveillance and response. Performance metrics can also be used to identify areas for process improvements.

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Metrics are reported separately for Salmonella, Shiga toxin-producing E. coli, Listeria, Shigella (optional), and Campylobacter (optional). Collectively, these pathogens are abbreviated as SSL(SC)

  1. Measures for laboratory surveillance
    1. Total number of SSL(SC) isolates and isolate-yielding specimens submitted to or recovered at the Public Health Lab (PHL)
    2. Number of SSL(SC) primary isolates or isolate-yielding specimens
  2. Measures for SSL(SC) clinical specimens or samples received at PHL
    1. Total number of preliminary positive SSL(SC) clinical specimens or samples received at PHL (regardless of if isolate-yielding or not)
    2. Total number and percent of isolate yielding SSL(SC) clinical specimens or samples received at PHL
  3. Measures for SSL(SC) primary isolates with pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) information
    1. OPTIONAL Percent of SSL(SC) primary isolates with PFGE testing at PHL
    2. Percent of SSL(SC) primary isolates with WGS testing at PHL
  4. Measures for time from SSL(SC) isolate receipt (or recovery) at PHL to upload to PulseNet
    1. OPTIONAL Time from SSL(SC) isolate receipt (or recovery) at PHL or PFGE request to pattern upload to PulseNet
    2. Time from SSL(SC) isolate receipt (or recovery) or WGS request at PHL to sequence upload to PulseNet
  5. Measure number of total SSL(SC) cases reported to epidemiology staff
    1. Total number of SSL(SC) cases reported to epidemiology staff
      1. OPTIONAL Percent of SSL(SC) cases with isolates and isolate-yielding specimens submitted to PHL
    2. Total number of confirmed SSL(SC) cases reported to epidemiology staff
    3. Total number of probable SSL(SC) cases reported to epidemiology staff
    4. Total number of suspect SSL(SC) cases reported to epidemiology staff
  6. Measures for case-based interview statistics
    1. Percent of SSL(SC) cases with attempted interview
      1. Percent of confirmed cases with attempted interview
      2. Percent of probable cases with attempted interview
      3. Percent of suspect cases with attempted interview
    2. Measure time from SSL(SC) case report to initial interview attempt
    3. Percent of SSL(SC) cases with exposure history obtained
      1. OPTIONAL Among SSL(SC) cases with an exposure history, percent with full shotgun or case exposure obtained
      2. OPTIONAL Time from case report to when an exposure history is obtained
  7. Number of SSL(SC) cluster and outbreak investigations
  8. Measures for identified SSL(SC) cluster and outbreak investigations with epidemiologic activity or action
    1. OPTIONAL Total number and percent of SSL(SC) cluster and outbreak investigations with routine interview of cases
    2. Total number and percent of SSL(SC) cluster and outbreak investigations where an analytic epidemiologic study was conducted
  9. Measures for cluster and outbreak investigations with vehicle/source identified
    1. Total number and percent of SSL(SC) cluster and outbreak investigations with confirmed vehicle/source identified
    2. OPTIONAL Total number and percent of SSL(SC) cluster and outbreak investigations with suspect vehicle/source identified
  10. Total number and percent of SSL(SC) cluster and outbreak investigations where food or environmental sample collected for testing
  11. Total number and percent of SSL(SC) cluster and outbreak investigations where environmental health, agriculture, regulatory, or food safety program staff were contacted
  12. Measures for SSL(SC) outbreaks
    1. Total number of SSL(SC) outbreaks, excluding multi-state outbreaks
    2. Total number and percent of SSL(SC) outbreaks (excluding multi-state outbreaks) reported/submitted to National Outbreak Reporting System (NORS)

Listed below are terms and definitions associated with the OutbreakNet Enhanced metrics. Terms are listed in the order they appear in the metrics. These definitions were adopted from the FoodCORE core definitions.

  • All measurements of time are in median days: Measurements will exclude weekend days. For laboratory time measurements, only isolates subtyped at the PHL should be included.
  • Isolate/Isolate-yielding specimen: This will include all SSL(SC) isolates (human, food, environmental, etc.) submitted to PHL and isolates recovered from specimen submitted to PHL. This can be further broken down to report total number of each category of isolates (human, food, environmental, etc.).
  • Primary isolates/isolate-yielding specimen: The first or representative SSL(SC) isolate/isolate-yielding specimen for each clinical case, or testing unit for any non-human isolates (i.e. isolates that are intended to be part of a subtyping workflow, such as PFGE or WGS).
  • Confirmed SSL(SC) cases: Definitions for confirmed, probable, and suspect cases will follow Council of State and Territorial Epidemiologists (CSTE)/National Notifiable Diseases Surveillance System (NNDSS) case definitions for each pathogen.
  • Exposure history: To include an interview (of any format) that assesses exposures prior to onset of illness, via an open-ended exposure history, or via a list of potential exposures. The key factor to be considered an exposure history is an interview that goes beyond assessment of high-risk settings and prevention education to ascertain food consumption/preference, or other exposure data.
  • SSL(SC) cluster: Two or more cases of Salmonella, STEC, Shigella, or Campylobacter infection with an indistinguishable PFGE pattern in 60 days, (120 days for Listeria infections), where the number of cases meets one or more of the following criteria:
    • The number of PFGE-matched isolates represent an increase over the expected baseline
    • Demographic or other epidemiologic characteristics among cases with PFGE-matched isolates indicate some deviation from expected values for the region
    • There is a PFGE-matched non-human isolate that would indicate a potential source of human infections

    In the absence of meeting the above criteria in a catchment area, a case-patient may be considered cluster-associated if the above criteria are met when including isolates from other jurisdictions or catchment areas. In the absence of meeting any of the above criteria, ill persons may be considered cluster-associated if there are demographic or epidemiologic indications of a common source of infection even without laboratory subtyping data to link cases.

  • Above baseline: A significant deviation (either in the number of isolates or a change in the demographic/temporal characteristics of cases) from expected values based on historical (laboratory) data for a specific SSL(SC) serotype or PFGE pattern.
  • Outbreak: Definition for an outbreak will follow the NORS definition.
  • Investigation: Any active epidemiologic follow-up resulting from the identification of a cluster. This could be initiating contact with a case (or the public health authority under whose jurisdiction a case falls) to ascertain direct case-based epidemiologic data, or active review of previously collected case-based data for cases later identified as cluster-associated.
  • Analytic epidemiologic study: A systematic, statistical analysis against a comparison group or within a cohort to test a hypothesis
  • Confirmed vehicle/source clusters: Clusters of infection where the etiologic agent has either been cultured from the vehicle or the vehicle has been statistically implicated in an analytic study.
  • Suspect vehicle/source clusters: Clusters of infection where investigational and/or laboratory data indicate a likely source/vehicle of infection without confirmation. For example: vehicle is a known risk factor, established errors in food preparation, or reported consumption by a high proportion of cluster-associated cases