Closing the investigation: OICC deactivation

Once it is deemed appropriate, the multi-jurisdictional outbreak investigation (OICC) can be deactivated. This can be done by either notifying all investigative partners through a final OICC call, or email.

Although two new cases have been reported since the products have been recalled by the CFIA, they both have illness onset dates before the recall.

For this outbreak, it is decided that no final OICC call is needed. Instead, email updates will be sent to all OICC members notifying them that the OICC investigation is closed, the date the outbreak can be declared over, as well as any new information that becomes available. Furthermore, an updated Public Health Alert (PHA) (see Module 2 – PHA) will be posted to inform everyone that the OICC investigation is closed.

Although the OICC is deactivated, the investigation may still continue at a lower level [e.g., enhanced surveillance for new cases meeting the case definition (matching the outbreak PFGE pattern)] for an unspecified time, and new data may still be obtained (e.g., new case interviews, laboratory results).

In this outbreak investigation, provinces had agreed to continue to interview new cases with the focused questionnaire (Module 3 – Focused questionnaire). After the OICC was deactivated, three more cases were interviewed with the questionnaire (see Module 4 – Line list for more details).

Following the deactivation of the OICC, results from the CFIA food and environmental samples were received:

Cases’ home samples:

  • Aug 2: Open hamburger samples from two cases’ homes (in Manitoba and Saskatchewan) were obtained and submitted for testing.
  • Aug 8: Both tested positive for the presence of E. coli O157:H7.
  • Aug 11: The PFGE patterns obtained from these samples matches the outbreak strain.

Facility and retail closed product samples:

  • Aug 2: 40 samples were obtained from the facility and at the retail level: eight samples from the recalled lots, 20 samples from the lots produced on previous and subsequent dates (as well as brands produced at the same facility but not included in the recall), and 12 environmental samples from the facility.
  • Aug 7: Four samples from the recalled lots (unopened boxes of product) tested positive for E. coli O157:H7. E. coli was not detected in the samples from the previous and subsequent lots of burgers or from the environmental samples.
  • Aug 11: All four PFGE patterns match the outbreak strain.

It is important to still include this laboratory and epidemiologic information in final documentation of the outbreak (e.g., final epidemiologic summary, chronology/timeline of events).