Following a potluck supper organized by the residency director of your training program, many of...

Calculating food-specific attack rates (i.e., number of people who became ill after eating a particular food divided by the total number who ate that food) is the most effective method to identify the probable source of infection in a known cohort outbreak.

Toronto Notes 2023 – Public Health, Outbreak Investigations:

“Foodborne outbreaks are best analyzed using food-specific attack rates to determine associations between individual foods and illness.”

MCCQE1 Objectives – Preventive Medicine > Epidemiologic Principles:

“Candidates must use epidemiologic tools, such as attack rates, to identify probable sources during outbreak investigations.”

Cohort study (C) is also acceptable but more time-intensive. Stool and food cultures (B, D) confirm the pathogen but not the source. HACCP (E) is a preventive method, not a tool for outbreak investigation.

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