Epidemiology Flashcards

A foodborne outbreak affects 40 of 100 people who ate potato salad and 10 of 100 who did not. What is the relative risk of illness from eating potato salad?

Answer: 4.0

Relative risk = attack rate in exposed (40/100 = 0.40) divided by attack rate in unexposed (10/100 = 0.10) = 4.0, indicating a fourfold higher risk in those who ate the potato salad.

Which term describes the systematic, ongoing collection, analysis, and interpretation of health-related data essential to planning, implementing, and evaluating public health practice?

Answer: Public health surveillance

Public health surveillance is the continuous, systematic process of collecting, analyzing, and interpreting data to guide timely public health action.

In a prospective cohort study of SSI risk factors, the loss to follow-up of sicker patients would most likely introduce which type of bias?

Answer: Selection bias

Loss to follow-up of sicker patients introduces selection bias because those who leave the study differ systematically from those who remain, distorting the true association between exposures and outcomes.

Which generation time concept is critical when modeling person-to-person transmission of a respiratory pathogen in a hospital setting?

Answer: Serial interval

The serial interval—the time between symptom onset in a primary case and symptom onset in a secondary case—is critical for modeling transmission dynamics and predicting outbreak trajectories.

A study reports an odds ratio of 0.3 for hand hygiene compliance and MRSA transmission. How should this be interpreted?

Answer: Hand hygiene reduces the odds of MRSA transmission by 70%

An odds ratio of 0.3 means the odds of MRSA transmission are 70% lower (1 - 0.3 = 0.7) among those with good hand hygiene compliance compared to those without.

Which surveillance method involves reviewing a random sample of patient medical records to identify HAIs that may have been missed by other detection methods?

Answer: Prevalence survey

A prevalence survey (point prevalence or period prevalence) examines a cross-section of patients at a specific time to identify all active infections, often uncovering cases missed by routine surveillance.

In infection control epidemiology, 'endemic' refers to which of the following?

Answer: The constant presence of disease at a predictable rate in a defined area

Endemic refers to the habitual presence of a disease or infectious agent within a given geographic area or population group at a predictable baseline rate.