Lecture 9: EID Drivers - Food

Question 1

What are the top 5 causative agents of food poisoning?

Answer 1

1. Norovirus
2. Salmonella
3. Clostridium perfringens
4. Campylobacter
5. Staphylococcus aureus

Question 2

How many pathogens have emerged as foodborne pathogens since the 1970s?

Answer 2

Over 20

Question 3

How does the mass production of food contribute to the spread/outbreak of foodborne illnesses?

Answer 3

Mass production means food is distributed to other locations so people can get sick even if they live far from where the food was made

Question 4

List the following for salmonellosis:
1. Agent
2. Reservoir
3. Transmission
4. How many cells are needed to cause infection

Answer 4

1. Non-typhoidal Salmonella enteric
2. Wild and domestic animals
3. Food, water, fomites, etc.
4. 1000 cells

Question 5

When can Salmonella contaminate eggs?

Answer 5

Before or after they are laid

Question 6

How does internal vs. external Salmonella contamination of the egg occur?

Answer 6

1. Internal
   - Infection of reproductive organs in hen
   - Various parts of the egg may contain Salmonella
2. External
   - Infection of vagina or fecal contamination from gut colonization
   - Contamination from external sources
   - Penetration of egg shell

Question 7

How does Salmonella infect plants?

Answer 7

• Uses similar virulence factors when infecting animal hosts
• Enters the plant leaf through the open stomata (or root tissues)

Question 8

Why can you eat a rare steak and not get sick?

Answer 8

Whole cuts are less risky because the pathogen is found on the surface, so it’s easier to kill
- Vs. ground meat: mixture of meats from multiple animals and pathogen can be found deep inside the meat

Question 9

List the following for norovirus:
1. Reservoir
2. How many viral particles are needed to cause infection

Answer 9

1. Humans
2. About 18 viral particles
   - Note: high mutation rate also contributes to high infectivity

Question 10

What foods contaminated by water are commonly involved in norovirus outbreaks?

Answer 10

• Leafy greens
• Fresh fruits
• Shellfish