A case of severe acute respiratory syndrome (SARS) was diagnosed immediately on signs of illness at a tourist site in China. Which action should be taken to protect the badly needed income from tourist dollars?

Correct Answer: C

Rationale: Quarantine is an enforced isolation or restriction of movement of those who have been exposed to an infectious agent during the incubation period; this is another method of controlling the reservoir. Quarantine was used effectively during the outbreak of SARS in 2003, when some hospitals required that their staff exposed to SARS patients remain at the hospital until proved to be symptom free at the end of the incubation period. Immunization and screening would not protect the population from exposure to this infectious disease. It is likely that others besides tourists could be exposed or infected by this disease, thus, closing airports would be ineffective in controlling the spread of the disease.

Correct Answer: C

Rationale: The natural history of disease model explains disease from prepathogenesis through resolution of the disease process. The epidemiological model involves the epidemiological triangle: agent, host, and environment. The ecosocial model emphasizes the role of evolving macro-level socioenvironmental factors to understand health and illness. The wheel model subscribes to multiple-causation rather than single-causation disease theory, and is more useful in analyzing complex chronic conditions and identifying factors that are amendable to intervention.

Correct Answer: B

Rationale: The person-place-time model suggests epidemiologists examine demographic characteristics of the community (person characteristics), geographic or environmental factors (place), and common time factors (time - or when the disease struck). Disease characteristics and health protection measures taken are not explicitly part of this model, though they may be considered in other contexts.

Correct Answer: D

Rationale: Confounding occurs when a third factor affects exposure and outcome. In nutritional epidemiology, dietary components (e.g., fat and calories) are correlated (D), complicating isolation of effects (e.g., does fat or total energy increase heart disease risk?). A and B are measurement issues, not confounding. C is false; methods like multivariable adjustment exist.

Correct Answer: A

Rationale: Relative risk (A) measures association (e.g., risk ratio in cohorts). Prevalence (B) and incidence (C) are frequencies, mortality rate (D) is deaths, not associations.