Scenario 6: You are contracted to investigate the source of an outbreak of food poisoning after a party at a conference venue or after a cruise. Where do you start?

Obtain the patient list from the relevant health service and the guest/passenger list including those who are not ill, so you have your full sampling frame to interview if necessary.

Obtain the menu from party/cruise organisers and use it to design a questionnaire including all possible food items available on the day of the party/cruise.

Interview all patients using the standard questionnaire and administer the questionnaire to a sample of controls. These could be other party /cruise guests who are not ill, or relatives of the sick people who were not at the party/cruise (to rule out other potential sources of contamination).

If you don’t have access to a decent sample of controls, and the potential contaminating product is available to the general community, conduct a population-based survey in the affected geographic area to supplement and compare with your cases.