A daycare center asked the nurse to come because they had several children out as a result of chickenpox. Which statement should the nurse make to the staff?

Correct Answer: C

Rationale: Other considerations for understanding the action of agents include their power to invade and infect large numbers of people (infectivity), their ability to produce disease in those infected with the agent (pathogenicity), and their ability to produce serious disease in their hosts (virulence). When the above concepts are applied, the chickenpox virus has high infectivity, high pathogenicity, and very low virulence.

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: The most advantageous research design, because it obtains more reliable information and can more easily establish a stronger temporal relationship between presumed causal factors and their effects, is a longitudinal cohort prospective study. A cross-sectional study examines relationships between potential causal factors and disease at a specific time. A descriptive study focuses on the amount and distribution of health and health problems within a population. A prospective study monitors a group of disease-free individuals to determine if and when disease occurs. A retrospective study compares individuals with a particular condition or disease with those who do not have the disease.

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.