Free Bachelor of Health Science Epidemiology Questions and Answers — Questions and Answers
Question 1: This is an example of conducting a survey with a representative sample of residents to inquire about their weekly exercise habits and whether they have been diagnosed with heart disease or not.
- Observational Cohort Study
- Observational Cross - sectional (Correct answer)
- Experimental study
- Not an analytical or epidemiologic study
Correct answer: Observational Cross - sectional
A cross-sectional study involves collecting data from a population or a representative sample at a single point in time. In this example, researchers are surveying residents once to simultaneously gather information on both exercise habits (exposure) and heart disease diagnosis (outcome). This 'snapshot' approach allows for the assessment of prevalence and associations between variables at that specific moment, without following individuals over time.
Question 2: People with new-onset Lyme disease were asked how often they walked in the forest, used repellents, and wore short sleeves as well as pants. The same questions were asked of twice as many people without Lyme disease from the same doctor's office. Then, the results from people with and without lyme disease were compared.
- Observational case study (Correct answer)
- Experimental
- Observational cross - sectional
- Observational cohort
Correct answer: Observational case study
This describes a case-control study, which is a type of observational study. Researchers identify individuals with a disease (cases, here Lyme disease) and a comparable group without the disease (controls). They then retrospectively compare the exposure histories (e.g., forest walking, repellent use) between the two groups to identify potential risk factors. The term 'observational case study' is likely a simplified or alternative phrasing for 'observational case-control study'.
Question 3: The people who have been studied were children whom are part of a health maintenance organization. At 2 months, each child was given one of the two vaccines against rotavirus infection based on a chance draw. After two weeks, a nurse reached out to the parents and asked if their children had any of a list of side effects.
- Observational cross - sectional
- Observational case study
- Experimental (Correct answer)
- Observational cohort
Correct answer: Experimental
This is an experimental study because the researchers actively intervene by assigning different treatments (two types of rotavirus vaccines) to the study participants based on a 'chance draw,' which indicates randomization. The purpose is to observe the effects of these interventions (side effects) and compare them between the groups. This direct manipulation of an exposure distinguishes experimental studies from observational ones.
Question 4: "Distribution" in the definition of epidemiology means:
- Who
- When
- Where
- All of the above (Correct answer)
Correct answer: All of the above
In epidemiology, 'distribution' refers to the patterns of health events in a population. This includes analyzing health outcomes by 'who' (person characteristics like age, sex, race), 'when' (time trends like seasonal, annual, or epidemic periods), and 'where' (place characteristics like geographic location or environmental factors). Understanding these aspects helps identify populations at risk and potential causes.
Question 5: In most cases, "determinants" in the definition of epidemiology means:
- Elements, Variables, Components, Control measures
- Variables, Components, Agents, Sources
- Causes, Risk factors, Sources, Agents (Correct answer)
- Sources, Influences, Contributors, Elements
Correct answer: Causes, Risk factors, Sources, Agents
'Determinants' in epidemiology refers to the factors or events that bring about a change in health. These include specific causes of disease, such as infectious agents or genetic predispositions, as well as risk factors that increase the likelihood of disease. It also encompasses sources of exposure and the agents themselves that lead to health outcomes.
Question 6: Several people on a cruise ship that went from Puerto Rico to the Panama Canal recently got sick with an illness that is similar to norovirus (formerly called Norwalk-like virus). Testing for norovirus is not easy to do on any nearby island, and even when it is possible, the test takes several days. If you are the epidemiologist who has been asked to go on the ship and look into this possible outbreak, your case definition should at least include: (Select one best answer)
- Clinical features, plus the exposure(s) you most suspect
- The nationally agreed standard case definition for disease reporting
- Clinical criteria, plus specification of time, place, and person (Correct answer)
- Suspect cases
Correct answer: Clinical criteria, plus specification of time, place, and person
A case definition for an outbreak investigation must clearly define who is considered a 'case' to ensure consistent identification. Given the difficulty in laboratory testing, clinical criteria (symptoms) are essential. Additionally, specifying time (when symptoms started), place (e.g., specific deck or time on the cruise), and person (e.g., age, passenger/crew status) helps to narrow down the affected population and characterize the outbreak's distribution.
Question 7: When comparing the number of sick people in a community to the rate of illness, rates are better for: (Choose one best answer)
- Telling physicians which strain of influenza is most prevalent
- Conducting surveillance for communicable diseases
- Deciding how many doses of immune globulin are needed
- Estimating subgroups at highest risk (Correct answer)
Correct answer: Estimating subgroups at highest risk
Rates of illness (e.g., incidence or prevalence rates) account for the size of the population at risk, unlike simple counts of sick people. By calculating rates for different subgroups (e.g., by age, sex, or occupation), epidemiologists can accurately compare disease frequency across these groups. This allows for the identification of specific populations that bear a disproportionately higher burden of illness, thus estimating subgroups at highest risk.
Question 8: Several people on a cruise ship that went from Puerto Rico to the Panama Canal recently got sick with a virus that is similar to norovirus (formerly called Norwalk-like virus). On any nearby island, it is hard to test for norovirus, and when it is possible, the test takes several days. If you are the epidemiologist who has been asked to go on the ship and look into this possible outbreak, how would you illustrate the time course of the outbreak? (Select one best answer)
- Secular trend
- Endemic curve
- Epidemic curve (Correct answer)
- Seasonal trend
Correct answer: Epidemic curve
An epidemic curve is a graphical representation that shows the number of new cases of a disease over time during an outbreak. It plots the onset of cases against the date or time of onset, providing a visual display of the outbreak's magnitude, its pattern of spread, and potential exposure period. This tool is crucial for understanding the time course and characteristics of an acute outbreak.
Question 9: On a cruise ship from Puerto Rico to the Panama Canal, a group of passengers has recently developed a gastrointestinal illness compatible with norovirus (formerly known as Norwalk-like virus). Norovirus testing is not readily accessible on nearby islands, and even where available, it takes several days to obtain results. What variables might be included in characterizing the outbreak by person?
- Symptoms
- Status as passenger or crew (Correct answer)
- Detailed food history (what person ate) while aboard ship
- Age of passenger
Correct answer: Status as passenger or crew
Characterizing an outbreak by 'person' involves identifying demographic and other relevant characteristics of affected individuals. In a cruise ship setting, distinguishing between passengers and crew is a critical variable. These groups often have different living conditions, food exposures, and social interactions, which could help pinpoint the source or mode of transmission of the illness.
Question 10: When examining surveillance data based on age, which of the following age groups is favored? (Select one best option)
- 10-year age groups
- 1-year age groups
- 5-year age groups
- Depends on the disease (Correct answer)
Correct answer: Depends on the disease
The most appropriate age grouping for surveillance data depends entirely on the specific disease or health outcome being studied. Different diseases affect various age groups disproportionately or have different age-specific risk factors. The choice of age groups aims to best capture the epidemiological patterns relevant to the disease, making 'depends on the disease' the correct answer.
Question 11: How does a cohort study differ from a case-control study?
- Subjects are asked about their exposure status in a cohort study but not in a case-control study
- Cohort studies are conducted to investigate chronic diseases, case-control studies are used for infectious diseases
- Subjects are enrolled or categorized on the basis of their exposure status in a cohort study but not in a case-control study (Correct answer)
- Cohort studies require many years to conduct, but case-control studies do not
Correct answer: Subjects are enrolled or categorized on the basis of their exposure status in a cohort study but not in a case-control study
This is the fundamental distinction between these two observational study designs. In a cohort study, researchers identify groups based on their exposure status (e.g., exposed vs. unexposed) and follow them forward in time to observe disease development. In contrast, a case-control study starts by identifying individuals based on their disease status (cases vs. controls) and then retrospectively investigates their past exposures.
Question 12: In a cross-sectional study, a prominent characteristic is that:
- It is synonymous with survey
- It usually provides information on prevalence rather than incidence
- It is more useful for descriptive epidemiology than it is for analytic epidemiology
- All of the above (Correct answer)
Correct answer: All of the above
A cross-sectional study is often synonymous with a survey, as it collects data at a single point in time. Because it captures existing cases and exposures simultaneously, it primarily provides information on the prevalence of a disease or condition, rather than its incidence (new cases). While it can identify associations, it's generally more useful for descriptive epidemiology than for definitively establishing cause-and-effect relationships.
Question 13: The epidemiologic triad of disease causation involves: (Select one best option)
- Time, place, person
- John Snow, Robert Koch, Kenneth Rothman
- Agent, host, environment (Correct answer)
- Source, mode of transmission, susceptible host
Correct answer: Agent, host, environment
The epidemiologic triad is a traditional model for understanding infectious diseases, proposing that disease results from the interaction of three components: the infectious agent (e.g., bacterium, virus), the susceptible host (e.g., human, animal), and the environment that brings the agent and host together and influences exposure and susceptibility. This model helps epidemiologists analyze disease patterns and develop interventions.
Question 14: In Figure 1.27, the timeline illustrates the natural history of disease. Item "A" takes place between the stage of susceptibility and the stage of subclinical disease. Item "B" occurs during the stage of subclinical disease. Item "C" happens between the stage of subclinical disease and the stage of clinical disease. Item "D" occurs shortly after the stage of clinical disease begins, and item "E" occurs at the end of the stage of clinical disease. Determine the appropriate letter from the time line in Figure 1.27 to each of the following stages representing the natural history of disease. Choose the correct answer.
- Onset of symptoms: A, Usual time of diagnosis: D, Exposure: C
- Onset of symptoms: C, Usual time of diagnosis: D, Exposure: A (Correct answer)
- Onset of symptoms: D, Usual time of diagnosis: B, Exposure: C
- Onset of symptoms: E, Usual time of diagnosis: B, Exposure: A
Correct answer: Onset of symptoms: C, Usual time of diagnosis: D, Exposure: A
Based on the description of the timeline: Exposure (A) occurs between susceptibility and subclinical disease. Onset of symptoms (C) happens between the subclinical stage (asymptomatic) and the clinical stage (symptoms appear). The usual time of diagnosis (D) occurs shortly after clinical disease begins, as symptoms prompt medical attention. This sequence accurately reflects the natural progression of disease.
Question 15: What can serve as a reservoir for an infectious agent?
- An symptomatic and asymptomatic human
- An animal
- The environment
- All of the above. (Correct answer)
Correct answer: All of the above.
A reservoir is the habitat in which an infectious agent normally lives, grows, and multiplies. This can include humans (both symptomatic and asymptomatic carriers), animals (e.g., zoonotic diseases), and the environment (e.g., soil, water, plants). For an agent to persist and be transmitted, it must have a suitable reservoir where it can survive and be transferred to a susceptible host.
Question 16: What type of exposure typically leads to a propagated epidemic?
- Continuous common source
- Person-to-person (Correct answer)
- Point source
- Intermittent common source
Correct answer: Person-to-person
A propagated epidemic is characterized by person-to-person transmission of an infectious agent. This means the disease spreads through direct or indirect contact between individuals, leading to a gradual increase in cases over time as the infection moves through a susceptible population. Unlike common source epidemics, which have a single exposure event, propagated epidemics show a sustained chain of transmission.
Free Bachelor of Health Science Epidemiology Questions and Answers
This is an example of conducting a survey with a representative sample of residents to inquire about their weekly exercise habits and whether they have been diagnosed with heart disease or not.