Hypothesis-generating questionnaires

Day 3: Wednesday July 23, 2014 (n=12)

A review of the literature reveals that E. coli O157:H7 outbreaks have been associated with a wide variety of food products as well as animal contact and exposure to untreated water. Sources of outbreaks of over the last few years have included unpasteurized milk, apple cider, various lettuces (including romaine), spinach, ground beef and ground beef products, venison, and strawberries. You check Outbreak Summaries and find that the last two E. coli O157:H7 outbreaks in Canada were associated with cheese made from unpasteurized milk and tenderized beef.

PulseNet Canada confirms that prior to this current cluster, this PFGE pattern combination has only been observed four times in the past six years. FoodNet Canada and your US-CDC colleagues both report that they have not seen this PFGE pattern combination before.

Six more cases are reported through PulseNet Canada: one from Saskatchewan, two from Manitoba, two from Alberta, and one from British Columbia. British Columbia is added to the OICC participant list and invited to the scheduled OICC call on Friday July 25, 2014.

The new case count (12 cases total) is communicated to the affected provinces by email. The provinces suggest that a technical epidemiology call is needed to discuss next steps before the OICC call on Friday. The call is held at 14:00. On the call, the provinces agree to re-interview their cases using a standardized E. coli hypothesis-generating questionnaire.

Question 2-4: What information would you collect on this type of questionnaire?

  • Hypothesis-generating questionnaires (also called “shotgun” questionnaires) collect demographic information (e.g., age, sex, occupation), clinical information (e.g., symptoms, illness onset date, hospitalization information) and exposure information (e.g., food history, travel history, contact with animals, water exposure).
  • The hypothesis-generating questionnaire used for this investigation can be downloaded here.