Outbreak Investigation Flashcards

Which measure is used to quantify the association between an exposure and illness in a cohort study during an outbreak investigation?

Answer: Relative risk

Relative risk (risk ratio) is the measure of association used in cohort studies, comparing the risk of illness among exposed versus unexposed individuals.

During an outbreak of Clostridioides difficile in a long-term care facility, which environmental surface is most commonly implicated as a reservoir?

Answer: Toilet seats, commodes, and bathroom surfaces

C. difficile spores persist on environmental surfaces especially in bathrooms and can survive for months, making toilets and commodes common reservoirs.

An epidemic curve showing a prolonged plateau with cases continuing over several weeks most likely indicates which type of outbreak?

Answer: Continuous common-source outbreak

A continuous common-source outbreak produces a prolonged plateau on the epidemic curve because ongoing exposure to the contaminated source continues over time.

When calculating an attack rate stratified by exposure status, what is the primary purpose of stratification?

Answer: To identify confounding variables and effect modifiers

Stratification helps identify confounders and effect modifiers by examining whether the exposure-disease association differs across subgroups.

A foodborne outbreak affects guests at a wedding reception. Which investigative approach would best identify the implicated food item?

Answer: Cohort study with food-specific attack rates among attendees

A cohort study calculating food-specific attack rates among all attendees is the most efficient method when the exposed population is well-defined and enumerable.

Which of the following best defines a 'cluster' in epidemiological terms during an outbreak investigation?

Answer: An aggregation of cases in a defined place and time that may or may not exceed the expected number

A cluster is an aggregation of cases in a defined place and time that may or may not exceed the expected background rate and may or may not have a common cause.

During outbreak investigation, which step should occur BEFORE implementing control measures?

Answer: Verifying the diagnosis through laboratory confirmation

Verifying the diagnosis through laboratory confirmation is essential before implementing targeted control measures to ensure appropriate interventions are applied.