The Case of Walkerton, Ontario (Canada), 2000
Walkerton is a small town of slightly fewer than 5,000 people in southern Ontario. The town is built along the banks of the Saugeen River, and is surrounded by rolling hills covered with farms. For the first part of the year 2000, it is much like any other town in the region, with residents busy with their own day-to-day concerns.
May 17 - a few residents feel unwell with some sort of gastrointestinal upset.
May 18 - an unusually large number of students are absent from school, and two are admitted to hospital.
May 19 - an even larger number of students are absent, a retirement home reports an outbreak of similar gastrointestinal illness, and many others in the community are calling their doctors, complaining of severe nausea and diarrhoea.
The paediatrician looking after the children admitted to hospital contacts the public health unit, which begins an investigation.
If you were in charge of the public health unit's investigation, what would you do first?
