SPEX Preventive Medicine 5 — Questions and Answers
Question 1: A community health department investigates a cluster of hepatitis A cases linked to a single restaurant. This is best classified as which type of outbreak?
- Propagated source outbreak
- Point source outbreak (Correct answer)
- Vector-borne outbreak
- Continuous common source outbreak
Correct answer: Point source outbreak
A restaurant exposure affecting multiple patrons at one event within a single incubation period is a classic point source outbreak.
Question 2: According to the National Institute for Occupational Safety and Health (NIOSH), the recommended exposure limit (REL) for noise in the workplace is:
- 85 dBA as an 8-hour TWA (Correct answer)
- 90 dBA as an 8-hour TWA
- 95 dBA as an 8-hour TWA
- 80 dBA as an 8-hour TWA
Correct answer: 85 dBA as an 8-hour TWA
NIOSH recommends a REL of 85 dBA as an 8-hour time-weighted average to prevent occupational noise-induced hearing loss.
Question 3: The Stages of Change (Transtheoretical) Model describes a patient who acknowledges a problem and intends to take action within 6 months but has not yet acted. This stage is called:
- Precontemplation
- Contemplation (Correct answer)
- Preparation
- Action
Correct answer: Contemplation
Contemplation is characterized by awareness of a problem and intention to change within 6 months, without commitment to immediate action.
Question 4: Which measure of association is used in a case-control study when disease is rare?
- Relative risk (risk ratio)
- Odds ratio (Correct answer)
- Incidence rate ratio
- Prevalence ratio
Correct answer: Odds ratio
Case-control studies cannot directly calculate risk; the odds ratio approximates the relative risk when disease prevalence is low (<10%).
Question 5: A preventive medicine physician is evaluating heat stress risk for outdoor construction workers. The most comprehensive index that accounts for temperature, humidity, radiant heat, and air movement is:
- Heat index
- Wet-bulb globe temperature (WBGT) (Correct answer)
- Apparent temperature
- Discomfort index
Correct answer: Wet-bulb globe temperature (WBGT)
WBGT integrates dry-bulb temperature, natural wet-bulb temperature, and globe temperature to provide a comprehensive heat stress index.
Question 6: In a randomized controlled trial, allocation concealment refers to:
- Blinding participants to their treatment assignment after randomization
- Preventing those who enroll participants from knowing future treatment assignments (Correct answer)
- Keeping outcome assessors unaware of group assignment
- Concealing the study hypothesis from participants
Correct answer: Preventing those who enroll participants from knowing future treatment assignments
Allocation concealment prevents selection bias by ensuring enrollers cannot predict or influence which group the next participant will be assigned to.
Question 7: Which environmental toxin is classically associated with Minamata disease, characterized by neurological manifestations including paresthesias, ataxia, and visual field constriction?
- Lead
- Arsenic
- Methylmercury (Correct answer)
- Cadmium
Correct answer: Methylmercury
Minamata disease results from methylmercury poisoning, typically from consumption of contaminated fish, causing severe neurological damage.
SPEX Preventive Medicine 5
A community health department investigates a cluster of hepatitis A cases linked to a single restaurant.
This is best classified as which type of outbreak?