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Review Questions

c. Epidemiology includes assessment of the distribution (including describing demographic characteristics of an affected population), determinants (including a study of possible risk factors), and application to control health problems (such as closing a restaurant).
a. The epidemiologic triad of disease causation refers to agent-host-environment.
a. Direct transmission occurs when an infectious agent is transmitted by direct contact or droplet spread. Droplet spread is considered direct transmission as the particles travel only a short distance and do not remain suspended in the air for long periods of time or distance.
a. Endemic refers to the continual and constant presence of a disease within a given geographic area. It may also be referred to as the usual rate of disease at any given time.
c. A study that assesses exposure and documents subsequent occurrence of disease in a group who all have the same disease is an observational cohort study.
a. The hallmark feature of an analytic epidemiologic study is use of an appropriate comparison group.
a. A study in which subjects are randomized into two intervention groups and monitored to identify health outcomes is a clinical trial, which is a type of experimental study.
b. Nightingale, the founder of professional nursing, engaged in epidemiological work by using statistics to identify a connection between poor sanitation and negative health outcomes. Nightingale gathered data to demonstrate that her sanitation reforms reduced deaths in military hospitals in Crimea.
b. In the subclinical stage, individuals have no overt symptoms. In infectious diseases, this stage includes an incubation period during which the pathogen multiplies to produce clinical symptoms. In noninfectious disease, it includes a latency period.
c. The prevalence rate is the proportion of a population with a health condition, such as pneumonia, at a certain point in time or time interval, such as the winter months.

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