WGU D450 Community Health HESI: 50 Questions with 100%
Correct Answers | 2026/2027 Edition
SECTION 1: Epidemiology and Population Health
Question 1.
A public health nurse is analyzing data from a county health department regarding new
cases of Lyme disease over the past 12 months. Which epidemiological measure
should the nurse calculate to determine the rate at which new cases are occurring in the
population?
A. Prevalence rate
B. Incidence rate
C. Case fatality rate
D. Attack rate
Correct Answer: B. Incidence rate
Rationale: Incidence rate measures the number of new cases of a disease occurring in a
specified population during a defined time period, making it the appropriate measure for
tracking new Lyme disease cases. Prevalence rate (A) measures the total number of
existing cases (new and old) at a specific point or period in time. Case fatality rate (C)
measures the proportion of diagnosed cases that result in death. Attack rate (D) is a
,specific type of incidence rate typically used during outbreak investigations for defined
populations over a short period.
Question 2.
During a community health fair, a nurse collects data on blood pressure readings,
smoking status, and physical activity levels from attendees. Which type of
epidemiological study design does this data collection most closely represent?
A. Case-control study
B. Cohort study
C. Cross-sectional study
D. Randomized controlled trial
Correct Answer: C. Cross-sectional study
Rationale: A cross-sectional study collects data from a population at a single point or
over a brief period to assess the prevalence of health outcomes, risk factors, or
characteristics, which matches the health fair data collection model. A case-control
study (A) compares individuals with a disease to those without to identify past
exposures. A cohort study (B) follows groups over time to observe outcomes. A
randomized controlled trial (D) involves intervention allocation and is not represented by
observational screening.
Question 3.
,A community health nurse is investigating an outbreak of gastrointestinal illness among
patrons of a local restaurant. To identify the specific food item responsible, the nurse
compares food consumption histories between ill patrons and well patrons who ate at
the same restaurant. Which epidemiological study design is being implemented?
A. Prospective cohort study
B. Retrospective cohort study
C. Case-control study
D. Community trial
Correct Answer: C. Case-control study
Rationale: A case-control study starts with the outcome (ill vs. well) and looks backward
to compare exposures (food consumption histories), which is the classic approach for
foodborne outbreak investigations. A prospective cohort study (A) follows exposed
individuals forward in time. A retrospective cohort study (B) uses existing records to
follow groups with known exposures. A community trial (D) is an intervention study at
the population level, not an outbreak investigation method.
Question 4.
The nurse epidemiologist notes that the crude mortality rate in County A is higher than
in County B. However, County A has a significantly larger population of adults over age
65. Which statistical adjustment should the nurse apply to make a valid comparison
between the two counties?
A. Standardized mortality ratio
B. Age-adjusted mortality rate
C. Years of potential life lost
, D. Proportional mortality ratio
Correct Answer: B. Age-adjusted mortality rate
Rationale: Age-adjusted mortality rates eliminate the influence of age differences in
population composition, allowing for valid comparisons between populations with
different age structures. The standardized mortality ratio (A) compares observed deaths
to expected deaths based on a standard population. Years of potential life lost (C)
measures premature mortality. Proportional mortality ratio (D) indicates the proportion
of deaths due to a specific cause relative to all deaths.
Question 5.
A community health nurse is reviewing the epidemiological triangle to explain the
resurgence of measles in a community with low vaccination rates. Which component of
the triangle represents the factor that has been most directly altered by vaccine
hesitancy?
A. Host
B. Agent
C. Environment
D. Reservoir
Correct Answer: A. Host
Rationale: Vaccination directly alters host susceptibility by creating immunity; vaccine
hesitancy increases host susceptibility to the measles agent. The agent (B) is the
measles virus itself, which has not changed due to hesitancy. The environment (C)
Correct Answers | 2026/2027 Edition
SECTION 1: Epidemiology and Population Health
Question 1.
A public health nurse is analyzing data from a county health department regarding new
cases of Lyme disease over the past 12 months. Which epidemiological measure
should the nurse calculate to determine the rate at which new cases are occurring in the
population?
A. Prevalence rate
B. Incidence rate
C. Case fatality rate
D. Attack rate
Correct Answer: B. Incidence rate
Rationale: Incidence rate measures the number of new cases of a disease occurring in a
specified population during a defined time period, making it the appropriate measure for
tracking new Lyme disease cases. Prevalence rate (A) measures the total number of
existing cases (new and old) at a specific point or period in time. Case fatality rate (C)
measures the proportion of diagnosed cases that result in death. Attack rate (D) is a
,specific type of incidence rate typically used during outbreak investigations for defined
populations over a short period.
Question 2.
During a community health fair, a nurse collects data on blood pressure readings,
smoking status, and physical activity levels from attendees. Which type of
epidemiological study design does this data collection most closely represent?
A. Case-control study
B. Cohort study
C. Cross-sectional study
D. Randomized controlled trial
Correct Answer: C. Cross-sectional study
Rationale: A cross-sectional study collects data from a population at a single point or
over a brief period to assess the prevalence of health outcomes, risk factors, or
characteristics, which matches the health fair data collection model. A case-control
study (A) compares individuals with a disease to those without to identify past
exposures. A cohort study (B) follows groups over time to observe outcomes. A
randomized controlled trial (D) involves intervention allocation and is not represented by
observational screening.
Question 3.
,A community health nurse is investigating an outbreak of gastrointestinal illness among
patrons of a local restaurant. To identify the specific food item responsible, the nurse
compares food consumption histories between ill patrons and well patrons who ate at
the same restaurant. Which epidemiological study design is being implemented?
A. Prospective cohort study
B. Retrospective cohort study
C. Case-control study
D. Community trial
Correct Answer: C. Case-control study
Rationale: A case-control study starts with the outcome (ill vs. well) and looks backward
to compare exposures (food consumption histories), which is the classic approach for
foodborne outbreak investigations. A prospective cohort study (A) follows exposed
individuals forward in time. A retrospective cohort study (B) uses existing records to
follow groups with known exposures. A community trial (D) is an intervention study at
the population level, not an outbreak investigation method.
Question 4.
The nurse epidemiologist notes that the crude mortality rate in County A is higher than
in County B. However, County A has a significantly larger population of adults over age
65. Which statistical adjustment should the nurse apply to make a valid comparison
between the two counties?
A. Standardized mortality ratio
B. Age-adjusted mortality rate
C. Years of potential life lost
, D. Proportional mortality ratio
Correct Answer: B. Age-adjusted mortality rate
Rationale: Age-adjusted mortality rates eliminate the influence of age differences in
population composition, allowing for valid comparisons between populations with
different age structures. The standardized mortality ratio (A) compares observed deaths
to expected deaths based on a standard population. Years of potential life lost (C)
measures premature mortality. Proportional mortality ratio (D) indicates the proportion
of deaths due to a specific cause relative to all deaths.
Question 5.
A community health nurse is reviewing the epidemiological triangle to explain the
resurgence of measles in a community with low vaccination rates. Which component of
the triangle represents the factor that has been most directly altered by vaccine
hesitancy?
A. Host
B. Agent
C. Environment
D. Reservoir
Correct Answer: A. Host
Rationale: Vaccination directly alters host susceptibility by creating immunity; vaccine
hesitancy increases host susceptibility to the measles agent. The agent (B) is the
measles virus itself, which has not changed due to hesitancy. The environment (C)
