BIOD 102 Portage Learning-Lab 6 Exam
(Public Health Case Study) Epidemiology
(2026/2027)
Section 1: Case Study Design & Data Collection
Section 2: Calculating Epidemiological Measures
Section 3: Interpreting Study Results & Biases
Section 4: Public Health Recommendations
Q1: In June 2026, a local health department receives multiple calls from individuals who
attended a corporate picnic and subsequently developed severe gastroenteritis. An epidemiologist
is dispatched to investigate. The initial step in this outbreak investigation is to:
A. Implement a quarantine for all attendees
B. Verify the diagnosis and confirm the existence of an outbreak [CORRECT]
C. Immediately close the catering company responsible
D. Administer prophylactic antibiotics to the sick individuals
Correct Answer: B
Rationale: The first step in any outbreak investigation is always to verify the diagnosis (ensuring
the symptoms are real and accurately identified) and confirm that an actual outbreak (an excess
of cases above baseline) is occurring before committing resources.
Q2: The epidemiologist determines that 100 out of 200 picnic attendees developed diarrhea,
fever, and abdominal cramps within 72 hours of the event. To standardize the investigation,
which of the following is the most appropriate "confirmed case" definition for this outbreak?
A. Anyone in the state who ate potato salad in June 2026
B. Any individual who attended the corporate picnic on June 10, 2026, and developed
laboratory-confirmed Salmonella [CORRECT]
.
,C. Any individual who feels nauseous after eating at a picnic
D. Any caterer who worked the event and has a headache
Correct Answer: B
Rationale: A confirmed case definition requires clinical criteria (compatible symptoms)
combined with laboratory confirmation, strictly restricted by time, place, and person (attending
the specific picnic on a specific date).
Q3: Because laboratory results will take 48 hours, the epidemiologist needs to act immediately.
Which of the following is the best "probable case" definition?
A. Any person in the county with diarrhea
B. Any individual who attended the corporate picnic on June 10, 2026, and developed acute
onset of diarrhea (3 or more loose stools in 24 hours) and fever within 72 hours [CORRECT]
C. Any individual who ate chicken at the corporate picnic
D. Any individual who works for the corporation and called in sick on June 11
Correct Answer: B
Rationale: A probable case definition uses clinical and epidemiologic criteria (time, place,
person, and specific symptom profile) without requiring laboratory confirmation, allowing for
rapid data collection and hypothesis generation.
Q4: To identify all potential cases, the health department sets up a hotline and asks all picnic
attendees to call if they are ill. This method of data collection is known as:
A. Active surveillance [CORRECT]
B. Passive surveillance
C. Syndromic surveillance
D. Sentinel surveillance
Correct Answer: A
Rationale: Active surveillance involves health officials actively reaching out or prompting the
population (e.g., via a hotline or direct interviewing) to report illness, whereas passive
surveillance relies on healthcare providers or individuals to spontaneously report cases to the
health department.
.
, Q5: The epidemiologist plots the onset times of the 100 cases on an epidemic curve. The curve
shows a sharp rise to a single peak, followed by a rapid decline over a period of approximately
12 hours, with no secondary waves. This pattern is most consistent with a:
A. Propagated source outbreak
B. Intermittent source outbreak
C. Point source outbreak [CORRECT]
D. Continuous common source outbreak
Correct Answer: C
Rationale: A point source outbreak occurs when a group of people is exposed to the same
harmful agent over a brief, defined period. The epidemic curve characteristically shows a rapid
rise, a sharp peak, and a rapid fall, reflecting the incubation period of the pathogen.
Q6: Based on the epidemic curve and the menu served at the picnic (hamburgers, hot dogs,
potato salad, and fruit), the epidemiologist enters the phase of analytical epidemiology. The
primary goal of this phase is to:
A. Identify the specific causative agent in the laboratory
B. Test hypotheses regarding possible exposures associated with illness [CORRECT]
C. Implement control measures to stop the outbreak
D. Communicate findings to the public
Correct Answer: B
Rationale: Analytical epidemiology uses quantitative methods (like cohort or case-control
studies) to test specific hypotheses generated during descriptive epidemiology, determining
which specific food or exposure is statistically linked to the illness.
Q7: Because the epidemiologist has a complete list of the 200 picnic attendees, which study
design is most appropriate and efficient to identify the source of the outbreak?
A. Case-control study
B. Cross-sectional survey
C. Retrospective cohort study [CORRECT]
.
(Public Health Case Study) Epidemiology
(2026/2027)
Section 1: Case Study Design & Data Collection
Section 2: Calculating Epidemiological Measures
Section 3: Interpreting Study Results & Biases
Section 4: Public Health Recommendations
Q1: In June 2026, a local health department receives multiple calls from individuals who
attended a corporate picnic and subsequently developed severe gastroenteritis. An epidemiologist
is dispatched to investigate. The initial step in this outbreak investigation is to:
A. Implement a quarantine for all attendees
B. Verify the diagnosis and confirm the existence of an outbreak [CORRECT]
C. Immediately close the catering company responsible
D. Administer prophylactic antibiotics to the sick individuals
Correct Answer: B
Rationale: The first step in any outbreak investigation is always to verify the diagnosis (ensuring
the symptoms are real and accurately identified) and confirm that an actual outbreak (an excess
of cases above baseline) is occurring before committing resources.
Q2: The epidemiologist determines that 100 out of 200 picnic attendees developed diarrhea,
fever, and abdominal cramps within 72 hours of the event. To standardize the investigation,
which of the following is the most appropriate "confirmed case" definition for this outbreak?
A. Anyone in the state who ate potato salad in June 2026
B. Any individual who attended the corporate picnic on June 10, 2026, and developed
laboratory-confirmed Salmonella [CORRECT]
.
,C. Any individual who feels nauseous after eating at a picnic
D. Any caterer who worked the event and has a headache
Correct Answer: B
Rationale: A confirmed case definition requires clinical criteria (compatible symptoms)
combined with laboratory confirmation, strictly restricted by time, place, and person (attending
the specific picnic on a specific date).
Q3: Because laboratory results will take 48 hours, the epidemiologist needs to act immediately.
Which of the following is the best "probable case" definition?
A. Any person in the county with diarrhea
B. Any individual who attended the corporate picnic on June 10, 2026, and developed acute
onset of diarrhea (3 or more loose stools in 24 hours) and fever within 72 hours [CORRECT]
C. Any individual who ate chicken at the corporate picnic
D. Any individual who works for the corporation and called in sick on June 11
Correct Answer: B
Rationale: A probable case definition uses clinical and epidemiologic criteria (time, place,
person, and specific symptom profile) without requiring laboratory confirmation, allowing for
rapid data collection and hypothesis generation.
Q4: To identify all potential cases, the health department sets up a hotline and asks all picnic
attendees to call if they are ill. This method of data collection is known as:
A. Active surveillance [CORRECT]
B. Passive surveillance
C. Syndromic surveillance
D. Sentinel surveillance
Correct Answer: A
Rationale: Active surveillance involves health officials actively reaching out or prompting the
population (e.g., via a hotline or direct interviewing) to report illness, whereas passive
surveillance relies on healthcare providers or individuals to spontaneously report cases to the
health department.
.
, Q5: The epidemiologist plots the onset times of the 100 cases on an epidemic curve. The curve
shows a sharp rise to a single peak, followed by a rapid decline over a period of approximately
12 hours, with no secondary waves. This pattern is most consistent with a:
A. Propagated source outbreak
B. Intermittent source outbreak
C. Point source outbreak [CORRECT]
D. Continuous common source outbreak
Correct Answer: C
Rationale: A point source outbreak occurs when a group of people is exposed to the same
harmful agent over a brief, defined period. The epidemic curve characteristically shows a rapid
rise, a sharp peak, and a rapid fall, reflecting the incubation period of the pathogen.
Q6: Based on the epidemic curve and the menu served at the picnic (hamburgers, hot dogs,
potato salad, and fruit), the epidemiologist enters the phase of analytical epidemiology. The
primary goal of this phase is to:
A. Identify the specific causative agent in the laboratory
B. Test hypotheses regarding possible exposures associated with illness [CORRECT]
C. Implement control measures to stop the outbreak
D. Communicate findings to the public
Correct Answer: B
Rationale: Analytical epidemiology uses quantitative methods (like cohort or case-control
studies) to test specific hypotheses generated during descriptive epidemiology, determining
which specific food or exposure is statistically linked to the illness.
Q7: Because the epidemiologist has a complete list of the 200 picnic attendees, which study
design is most appropriate and efficient to identify the source of the outbreak?
A. Case-control study
B. Cross-sectional survey
C. Retrospective cohort study [CORRECT]
.
