Which is an example of epidemiologic evidence in an outbreak investigation?

• A. Patterns in where and when people got sick, past outbreaks, caused by the same germ
• B. Interviews with sick people to look for foods or other exposures occurring more often than expected
• C. Discovery of clusters of unrelated sick people who ate at the same restaurant, shopped at same grocery store, or attended the same event
• D. All of the above

Answer: (D)

Epidemiologic evidence in an outbreak investigation comes from describing who got sick and when and where (the pattern of illness), asking sick people about exposures to identify common factors, and spotting clusters of cases linked to the same place or event. Describing time and place helps reveal the distribution and possible source; interviewing cases highlights exposures that occur more often than expected; finding clusters around a shared venue or event suggests a common exposure driving transmission. Taken together, these elements all exemplify epidemiologic evidence, so all of the above is the best answer.