In a particular community, the rate of new cases of diabetes and the rate of new cases of flu during the month of January were precisely the same. Which disease would have the higher prevalence rate?

Correct Answer: B

Rationale: Diabetes would have the higher prevalence rate because it is a long-term chronic condition that typically does not decrease. Although flu might have a higher incidence rate of new cases, because flu is typically of short duration, the prevalence rate would remain low. Flu is contagious, which could increase the incidence rate but not the prevalence rate.

Correct Answer: C

Rationale: Measures of effect (e.g., risk ratio, odds ratio) quantify the strength of the association between exposure and outcome (C), indicating how strongly they are linked (e.g., smoking and lung cancer). A is about causation, not measurement. B relates to intervention effects, not association strength. D addresses confounders, not the exposure-outcome link.

Correct Answer: B

Rationale: Surveillance (B) tracks disease patterns to monitor and control spread (e.g., flu surveillance). Diagnosis (A) and treatment (C) are clinical, while risk factor identification (D) is a study goal, not surveillance.

Correct Answer: C

Rationale: Herd immunity (C) is population resistance when a high proportion are immune (e.g., via vaccination, B), protecting others. A is individual, D is passive.

Correct Answer: B

Rationale: Case definition (B) standardizes criteria for consistent disease identification (e.g., COVID-19 symptoms/tests). A, C, and D are unrelated.