HIC Foodborne Illness Investigation 2 — Questions and Answers
Question 1: During a foodborne illness outbreak investigation, what is the primary purpose of a case-control study?
- To identify the source of contamination by comparing food exposures of ill vs. well individuals (Correct answer)
- To determine the total number of people who ate at the establishment
- To measure the temperature of all food items served
- To calculate the establishment's annual inspection score
Correct answer: To identify the source of contamination by comparing food exposures of ill vs. well individuals
A case-control study compares the food exposure histories of sick individuals (cases) to healthy individuals (controls) to identify the likely vehicle of illness.
Question 2: Which agency is the primary federal partner for health inspectors when a multi-state foodborne illness outbreak is identified?
- FDA and CDC (Correct answer)
- USDA and EPA
- OSHA and DHS
- FTC and FBI
Correct answer: FDA and CDC
The FDA and CDC are the primary federal partners for multi-state outbreak investigations, with CDC coordinating epidemiology and FDA/USDA handling food and traceback investigations.
Question 3: What does an 'attack rate' measure in a foodborne illness outbreak investigation?
- The percentage of exposed individuals who became ill (Correct answer)
- The speed at which the pathogen multiplies in food
- The number of hospitalizations per outbreak
- The force used by health inspectors during inspections
Correct answer: The percentage of exposed individuals who became ill
The attack rate is the proportion of people exposed to a suspected vehicle who developed illness, used to identify the most likely food source.
Question 4: A health inspector collects a stool sample from a food handler suspected of causing a Salmonella outbreak. How long should the specimen typically be kept refrigerated before lab submission?
- No more than 24 hours at 35–46°F (2–8°C) (Correct answer)
- Up to 72 hours at room temperature
- At least 1 week frozen at -4°F (-20°C)
- Exactly 48 hours at 50°F (10°C)
Correct answer: No more than 24 hours at 35–46°F (2–8°C)
Stool specimens for bacterial culture should be refrigerated at 2–8°C and submitted to the laboratory within 24 hours to preserve pathogen viability.
Question 5: Which of the following best describes the 'incubation period' in a foodborne illness context?
- The time between consuming contaminated food and the onset of symptoms (Correct answer)
- The time food spends in the temperature danger zone
- The period during which food handlers must be excluded from work
- The duration of the health inspector's on-site investigation
Correct answer: The time between consuming contaminated food and the onset of symptoms
The incubation period is the elapsed time from ingestion of a contaminated food to the appearance of illness symptoms, which helps narrow down the causative pathogen.
Question 6: An outbreak of bloody diarrhea with no fever is reported among patrons of a hamburger restaurant. Which pathogen should the health inspector suspect first?
- Escherichia coli O157:H7 (Correct answer)
- Staphylococcus aureus
- Bacillus cereus
- Vibrio parahaemolyticus
Correct answer: Escherichia coli O157:H7
E. coli O157:H7 classically causes bloody diarrhea (hemorrhagic colitis) without fever and is strongly associated with undercooked ground beef.
Question 7: What is the recommended approach when interviewing an outbreak victim about food history?
- Use an open-ended questionnaire covering 7 days before symptom onset without suggesting specific foods (Correct answer)
- Ask only about the most recent meal the person ate
- Focus exclusively on foods consumed at the suspect establishment
- Begin by telling the patient which food you believe caused their illness
Correct answer: Use an open-ended questionnaire covering 7 days before symptom onset without suggesting specific foods
A comprehensive, unbiased food history spanning 7 days (or at least the full incubation period) prevents anchoring bias and captures all potential exposure vehicles.
HIC Foodborne Illness Investigation 2
During a foodborne illness outbreak investigation, what is the primary purpose of a case-control study?