CBIC Outbreak Investigation 4 — Questions and Answers
Question 1: During an outbreak investigation, a 'hypothesis-generating interview' is conducted to:
- Confirm the mode of transmission statistically
- Broadly explore exposures before formulating a specific hypothesis (Correct answer)
- Collect throat swabs from suspected cases
- Determine antibiotic resistance profiles
Correct answer: Broadly explore exposures before formulating a specific hypothesis
Hypothesis-generating interviews use open-ended questions to explore all potential exposures before a formal analytical study is designed.
Question 2: A prolonged common-source outbreak with intermittent exposures produces which epidemic curve pattern?
- Single sharp peak
- Flat, extended plateau
- Multiple peaks at regular intervals equal to the incubation period
- Irregular, scattered cases over an extended period (Correct answer)
Correct answer: Irregular, scattered cases over an extended period
Intermittent common-source outbreaks show irregular, scattered case distributions because exposures occur at different times and doses.
Question 3: Which agency must be notified when a healthcare facility identifies a novel or emerging pathogen cluster that poses a public health threat?
- The Joint Commission only
- State or local health department (Correct answer)
- OSHA regional office
- CMS regional office
Correct answer: State or local health department
State and local health departments are the primary mandatory reporting recipients for novel or reportable communicable disease clusters in healthcare settings.
Question 4: An IP is investigating a cluster of post-operative endophthalmitis cases. Cultures grow Pseudomonas aeruginosa from all cases. The NEXT priority step is to:
- Immediately close the operating room
- Identify common exposures: surgeon, procedure, instruments, or solutions (Correct answer)
- Report to the FDA without further investigation
- Restrict all ophthalmic surgeries hospital-wide
Correct answer: Identify common exposures: surgeon, procedure, instruments, or solutions
Identifying shared exposures among cases (same surgeon, instrument set, or irrigating solution) is the critical next step to pinpoint the source.
Question 5: The concept of 'herd immunity threshold' is most relevant during an outbreak investigation when:
- Determining antibiotic prophylaxis doses
- Estimating the vaccination coverage needed to halt transmission (Correct answer)
- Calculating environmental decontamination intervals
- Assessing hand hygiene product efficacy
Correct answer: Estimating the vaccination coverage needed to halt transmission
The herd immunity threshold tells investigators what proportion of the population must be immune to interrupt sustained transmission of the pathogen.
Question 6: In a healthcare outbreak investigation, what does a secondary attack rate specifically measure?
- Mortality among confirmed cases
- Rate of new infections among close contacts of primary cases (Correct answer)
- Proportion of staff colonized versus infected
- Proportion of environmental surfaces testing positive
Correct answer: Rate of new infections among close contacts of primary cases
The secondary attack rate measures how often susceptible contacts of a confirmed case develop illness, indicating the pathogen's transmissibility.
Question 7: During outbreak debriefing, which document serves as the primary record summarizing findings, conclusions, and corrective actions?
- Infection control risk assessment (ICRA)
- Outbreak investigation report (Correct answer)
- Antibiogram report
- Facility infection control plan
Correct answer: Outbreak investigation report
The formal outbreak investigation report documents the timeline, epidemiological findings, likely source, and implemented control measures for accountability and future reference.
CBIC Outbreak Investigation 4
During an outbreak investigation, a 'hypothesis-generating interview' is conducted to: