1. Epidemiology & Surveillance
1. Incidence refers to
A. Total number of existing cases in a population at a
specific time
B. Number of new cases over a period of time
C. Proportion of exposed who develop disease
D. Number of deaths over a period
Answer: B
Rationale: Incidence measures new cases in a defined
time frame, indicating risk of disease onset.
2. Prevalence differs from incidence because
prevalence
A. Excludes recovered cases
B. Focuses only on fatal cases
C. Reflects both new and existing cases at a point in
time
D. Is always lower than incidence
Answer: C
Rationale: Prevalence counts all cases present (new +
existing) at a specific point.
3. During an outbreak investigation, the first step is
to
A. Implement control measures
B. Confirm the diagnosis
, C. Calculate attack rate
D. Hypothesize cause
Answer: B
Rationale: Confirming the diagnosis ensures accurate
case definition before other steps.
4. A case–control study is most appropriate when
A. Disease is common
B. Exposure data are unreliable
C. You need to calculate incidence directly
D. Disease is rare
Answer: D
Rationale: Case–control studies are efficient for rare
diseases, starting with affected individuals.
5. Attack rate is calculated as
A. (New cases)/(Population at risk) × 100
B. (Total cases)/(Total population) × 100
C. (Deaths)/(Total cases) × 100
D. (Recovered)/(New cases) × 100
Answer: A
Rationale: Attack rate is a form of cumulative incidence:
new cases among those at risk.
6. A sentinel surveillance system
A. Captures every case in a population
B. Uses selected reporting sites for intensive
monitoring
, C. Relies on voluntary self‐reporting by patients
D. Only tracks communicable diseases
Answer: B
Rationale: Sentinel sites provide high‐quality data on
selected conditions or populations.
7. The basic reproduction number (R₀) > 1 indicates
A. Disease is in decline
B. Each case causes less than one new case
C. Disease will spread in the population
D. Herd immunity is achieved
Answer: C
Rationale: R₀ > 1 means each case infects more than one
person, leading to spread.
8. A cohort study
A. Is retrospective only
B. Follows exposed and unexposed groups over time
C. Begins with people who have the disease
D. Cannot assess multiple outcomes
Answer: B
Rationale: Cohort designs follow groups based on
exposure status to observe multiple outcomes.
9. Passive surveillance relies on
A. Health department–initiated data collection
B. Routine reporting by health providers/labs
C. Systematic sampling from the community
D. Direct observation by public health staff
1. Incidence refers to
A. Total number of existing cases in a population at a
specific time
B. Number of new cases over a period of time
C. Proportion of exposed who develop disease
D. Number of deaths over a period
Answer: B
Rationale: Incidence measures new cases in a defined
time frame, indicating risk of disease onset.
2. Prevalence differs from incidence because
prevalence
A. Excludes recovered cases
B. Focuses only on fatal cases
C. Reflects both new and existing cases at a point in
time
D. Is always lower than incidence
Answer: C
Rationale: Prevalence counts all cases present (new +
existing) at a specific point.
3. During an outbreak investigation, the first step is
to
A. Implement control measures
B. Confirm the diagnosis
, C. Calculate attack rate
D. Hypothesize cause
Answer: B
Rationale: Confirming the diagnosis ensures accurate
case definition before other steps.
4. A case–control study is most appropriate when
A. Disease is common
B. Exposure data are unreliable
C. You need to calculate incidence directly
D. Disease is rare
Answer: D
Rationale: Case–control studies are efficient for rare
diseases, starting with affected individuals.
5. Attack rate is calculated as
A. (New cases)/(Population at risk) × 100
B. (Total cases)/(Total population) × 100
C. (Deaths)/(Total cases) × 100
D. (Recovered)/(New cases) × 100
Answer: A
Rationale: Attack rate is a form of cumulative incidence:
new cases among those at risk.
6. A sentinel surveillance system
A. Captures every case in a population
B. Uses selected reporting sites for intensive
monitoring
, C. Relies on voluntary self‐reporting by patients
D. Only tracks communicable diseases
Answer: B
Rationale: Sentinel sites provide high‐quality data on
selected conditions or populations.
7. The basic reproduction number (R₀) > 1 indicates
A. Disease is in decline
B. Each case causes less than one new case
C. Disease will spread in the population
D. Herd immunity is achieved
Answer: C
Rationale: R₀ > 1 means each case infects more than one
person, leading to spread.
8. A cohort study
A. Is retrospective only
B. Follows exposed and unexposed groups over time
C. Begins with people who have the disease
D. Cannot assess multiple outcomes
Answer: B
Rationale: Cohort designs follow groups based on
exposure status to observe multiple outcomes.
9. Passive surveillance relies on
A. Health department–initiated data collection
B. Routine reporting by health providers/labs
C. Systematic sampling from the community
D. Direct observation by public health staff
