FoodCORE SSL Metrics

SSL metrics apply to Salmonella, Shiga toxin-producing Escherichia coli (STEC), Listeria, Shigella, and Campylobacter (reporting for Shigella and Campylobacter is optional). The FoodCORE performance metrics are a list of measurable activities covering diverse aspects of outbreak response. These activities span from outbreak surveillance and detection through investigation, response, control, and prevention measures. Using the metrics, each center provides data about the burden, timeliness, and completeness of foodborne disease activities related to the key areas of activity. Data for all years of the FoodCORE program are available.

Download: SSL Rationale and Intent [10 pages]

Isolate/Specimen-based Metrics

1. Measures for isolates/isolate-yielding specimens submitted to or recovered at the Public Health Laboratory (PHL).
   1. Total number of isolates and isolate-yielding specimens¹
   2. Number of primary isolates/isolate-yielding specimens
2. Measures for clinical specimens or samples received at PHL (n/a for Listeria)
   1. Total number of preliminary positive clinical specimens or samples received at PHL (regardless of if isolate-yielding or not).
   2. Number and percent of isolate-yielding specimens or samples
3. Time from isolation/isolate-yielding specimen collection to receipt at PHL¹
4. Time from receipt of isolate-yielding specimens at PHL to recovery of isolate
5. Percent of primary isolates with complete serotype (serogroup for Shigella) information (n/a for Listeria)¹
6. Time from isolate receipt (or recovery) at PHL to serotype (serogroup for Shigella) result (n/a for Listeria)¹
7. Measures for primary isolates with PFGE/WGS results
   1. Percent of primary isolates with PFGE results¹
   2. Percent of primary isolates with WGS results
8. Measures for PFGE/WGS timeliness
   1. Time from isolate receipt (or recovery) at PHL to PFGE upload to PulseNet¹
   2. Time from isolate receipt (or recovery) at PHL to WGS sequence being shared with national database
   3. Time from receipt (or recovery) at PFGE laboratory to upload to PulseNet
   4. Time from receipt (or recovery) at WGS laboratory to sequence being shared with national database

Case-based Metrics

9. Measures for cases reported to epidemiology staff
   1. Number of laboratory confirmed cases reported to epidemiology staff¹
   2. Number of probable cases reported to epidemiology staff (n/a for Listeria)
   3. Number of suspect cases reported to epidemiology staff (n/a for Listeria and Campylobacter)
10. Measures for case interviews
    1. Measures for attempted interview completeness
       1. Percent of laboratory confirmed cases with attempted interview¹
       2. Percent of probable/suspect cases with attempted interview (n/a for Listeria)
    2. Measures for attempted interview timeliness
       1. Time from confirmed case report to initial interview attempt¹
       2. Time from probable/suspect case report to initial interview attempt (n/a for Listeria)
    3. Measures for completed interview timeliness
       1. Time from confirmed case report to completed interview
       2. Time from probable/suspect case report to completed interview (n/a for Listeria)
    4. Percent of confirmed cases with complete demographic data
    5. Percent of confirmed cases with exposure history obtained¹
       1. Percent of confirmed cases with full shotgun or case exposure interview completed
    6. Percent of cases with serotype (serogroup for Shigella) information (n/a for Listeria and Campylobacter)
    7. Percent of cases with PFGE information¹
       1. Percent of cases with PFGE where complete epidemiologic data is collected¹
    8. Reason for not interviewing cases (lost to follow-up, refused, time lag too long, other)

Investigation-based Metrics

11. Number of investigations (clusters and outbreaks)
12. Measures for identified investigations with epidemiologic activity or action
    1. Number and percent of investigations with routine interview of cases¹
    2. Number and percent of investigations with supplemental or targeted interviewing of cases
    3. Number and percent of investigations where an analytic epidemiologic study was conducted¹
13. Number and percent of investigations with suspect vehicle/source identified¹
14. Number and percent of investigations with confirmed vehicle/source identified¹
15. Measures for investigations with identified vehicle/source where control measures or public health actions were taken
    1. Number and percent of investigations with exclusion of a(an) ill person(s) from high risk setting
    2. Number and percent of investigations with remediation or closure of an establishment linked to illness
    3. Number and percent of investigations with educational campaigns during outbreaks (beyond individual case education)
    4. Number and percent of investigations with media or public messaging (web updates, press release, etc.)
    5. Number and percent of investigations with regulatory action (recall, hold, etc.)
16. Number and percent of investigations with link to a common location of exposures (e.g., restaurant, food establishment, nursing home, etc.) where an environmental health assessment was conducted¹
17. Number and percent of investigations where food or environmental sample collected for testing¹
18. Number and percent of investigations where environmental health, agriculture, regulatory, or food safety program staff were contacted.
19. Number and percent of outbreaks where NORS form completed¹

NOTE: ¹Minimum reporting requirement for FoodCORE Centers

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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 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: To be limited to the first or representative isolate or sample for each case or testing unit for non-human isolates.

Laboratory confirmed, probable, and suspect cases: Refer to NNDSS case definitions for each pathogen (http://wwwn.cdc.gov/nndss/case-definitions.html)

Complete demographic data: To include State, County, Birth Month, Birth Year, Sex, Race

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.

Complete epidemiologic data: To include complete demographic data as well as an exposure history.

Cluster: Two or more cases of Salmonella or STEC infection with an indistinguishable PFGE pattern in 60 days, or 120 days for Listeria infections, where the number of cases meets one or more of the following criteria:

1. The number of PFGE-matched isolates represent an increase over the expected baseline
2. Demographic or other epidemiologic characteristics among cases with PFGE-matched isolates indicate some deviation from expected values for the region
3. 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 should 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 should 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.

This definition also includes clusters that may be defined as outbreaks in your jurisdiction.

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 serotype or PFGE pattern.

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.

Notification: Report of a case or cluster (depending on the metric) to epidemiology staff, i.e., when epidemiology staff first were made aware of a specific case or an identified cluster. This could be via routine communication such as a laboratory report or accessing a database, or via direct complaints, reports from another health authority (local, other state, federal, etc.), media report, or other means of communication.

Analytic epidemiologic study: A systematic, statistical analysis against a comparison group or within a cohort to test a hypothesis

Vehicle/Source Identified:

SUSPECT vehicle/source clusters: Clusters of infection where investigational and/or laboratory data indicate a likely source/vehicle of infection without confirmation: vehicle is a known risk factor, established errors in food preparation, or reported consumption by a high proportion of cluster-associated cases.

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.

Control measure: to include interventions such as exclusion of an ill person(s) from high risk setting, remediation or closure of an establishment linked to illness, educational campaigns during daycare outbreaks, etc. To be considered a control measure, activities should extend beyond the routine educational component of an interview or exposure assessment.

Public health action: to include media, public messaging (web updates, press release, etc.), or regulatory action (recall, hold, etc.). To be considered a public health action, activities should extend beyond the routine investigation activities and reach at-risk individuals beyond identified cases. A public health action should be included in the metrics if the FoodCORE Center was directly involved in the action, or is aware that a public health action was taken during a multijurisdictional investigation. For example, if CDC produces public messaging during a multistate outbreak investigation that a FoodCORE Center is involved in, that investigation would be associated with a public health action for the purposes of the metrics.