Detailed Answers 2026/2027.
Which epidemiological term best describes the following statement?
"Signs and symptoms of listeriosis can appear from 3 to 70 days after exposure to the bacteria,
with a median time of 3 weeks."
A. Latent period
B. Incubation period
C. Communicability period
D. Shedding period
E. Pathology period - Answer B
Public Health Ontario reports that
the annual number of cases of listeriosis for the years 2009 to 2015 ranged between 43 and 65
(average: 53 cases); however, in 2016, 96 cases were reported. Which of the following disease
patterns is most consistent with
this description?
A. Yearly
B. Sporadic
C. Endemic
D. Epidemic
E. Pandemic - Answer D
You are working for Public Health Ontario, and are helping design a research study to do active
surveillance for listeriosis in a high- risk population. You expect the prevalence of listeriosis in
this population to be 5%. You want your prevalence estimate to have a precision of +/- 2% and
95% confidence. The minimum required sample size for your study is:
A. 10
B. 91
C. 233
D. 457
E. 4,562 - Answer D
,You conduct the active surveillance described above, and you estimate a prevalence of 8% with
a 95% confidence interval = (5%, 11%). Which of the following statements
best describes this confidence interval?
A. There is a 95% probability that the actual prevalence falls between 5% and
11%
B. There is a 5% probability that the actual prevalence is below 5%
C. There is a 95% probability that the actual prevalence would be lower than 5% or
higher than 11%
D. There is a 95% probability that the actual prevalence is 8%
E. More than one of the above is correct - Answer A
You set up a food safety program with Public Health Ontario to test all cheeses and other foods
commonly associated with listeriosis to ensure that no Listeria contaminated food is brought
into this high-
risk population. Given this objective, and assuming the use of multiple food safety tests in
combination, which of the following approaches would be best for you to use?
A. Interpret the tests in series to achieve higher sensitivity
B. Interpret the tests in series to decrease the sensitivity
C. Interpret the test in series to achieve higher specificity
D. Interpret the tests in parallel to achieve a higher sensitivity
E. Interpret the tests in parallel to achieve a higher specificity - Answer D
When epidemiologists judge the evidence to establish possible causes of a health outcome, we
consider:
A. The estimated strength of association between an exposure and outcome
B. Evidence that the exposure of interest appeared befor
e the outcome
C. Evidence showing that reduction
s in the exposure level do not affect the risk of the outcome
D. Two of the above
E. All of the above - Answer D
What is a sufficient cause?
, A. Any agent that is required for the development of a given disease
B. A factor that contributes towards disease causation but is not necessary
C. A factor or combination of factors that will inevitably produce disease
D. A component cause that is present in any combination of factors that produce
disease
E. None of the above - Answer C
Academic records were used to confirm students' self-reported grade point averages in a
research study. By using this validation process instead of just relying on students' provided
responses, the researchers are reducing the likelihood of which of the following?
A. Selection bias
B. Information bias
C. Confounding bias
D. Surveillance bias
E. None of the above - Answer B
In a research study, daycares
were selected at random, and every child in each daycare
was included in the sample. This best describes which type of sampling method?
A. Simple random sampling
B. Systematic random sampling
C. Stratified random sampling
D. Cluster sampling
E. Multistage sampling - Answer D
The local public health department releases a new set of internet memes to help increase the
practice of good hand washing in the general public. This represents which level of prevention?
A. Pre-Primary
B. Primary
C. Secondary
D. Tertiary
E. None of the above - Answer B