1. Food Safety and Foodborne Disease Mark D. Sobsey
ENVR 421
Food Safety and Foodborne Disease
Mark D. Sobsey

2. BACTERIA Salmonella spp. Clostridium botulinum Staphylococcus aureus
Campylobacter jejuni
Yersinia enterocolitica and Y. pseudotuberculosis
Listeria monocytogenes
Vibrio cholerae O1, non-O1
V. parahaemolyticus; V. spp.
Vibrio vulnificus
Clostridium perfringens
Bacillus cereus
Aeromonas hydrophila and spp.
Plesiomonas shigelloides
Shigella spp.
Streptococcus
Enterovirulent Escherichia coli Group (EEC Group)
Escherichia coli - enterotoxigenic (ETEC)
Escherichia coli - enteropathogenic (EPEC)
Escherichia coli O157:H7 enterohemorrhagic (EHEC)
Escherichia coli - enteroinvasive (EIEC)

3. NATURAL TOXINS Shellfish toxins (PSP, DSP, NSP, ASP)
Ciguatera poisoning (fish)
Shellfish toxins (PSP, DSP, NSP, ASP)
Scombroid poisoning (fish)
Tetrodotoxin (Pufferfish)
Mushroom toxins
Aflatoxins
Pyrrolizidine alkaloids
Phytohaemagglutinin (Red kidney bean poisoning)
Grayanotoxin (Honey intoxication)

4. Spongioform Encephalopathic Agents
Enteric Viruses
Hepatitis A virus
Hepatitis E virus
Rotavirus
Norwalk virus group
Other viral agents
Prions:
Spongioform Encephalopathic Agents
“Mad Cow Disease” Agent; Creutzfeldt-Jacob Disease Agent; Scrapie in sheep, etc.

5. Parasitic Protozoa and Worms
Giardia lamblia
Entamoeba histolytica
Cryptosporidium parvum
Cyclospora cayetanensis
Anisakis sp. and related worms
Diphyllobothrium spp.
Nanophyetus spp.
Eustrongylides sp.
Acanthamoeba and other free-living amoebae
Ascaris lumbricoides and Trichuris trichiura

6. Sources of Foodborne Enteric Microbial Contamination
Food handler‑associated contamination
Inadequate personal hygiene  fecal contamination of foods (e.g., hands)
Food processing
Equipment, packaging and personnel contaminate foods during processing
Food Storage: time and temperature abuse  bacterial growth
Fecal contamination prior to harvest or collection
Animal foods contaminated naturally by infection (e.g., salmonella)
Surface contamination (e.g., feces on fur, feathers, hooves, etc.)
Shellfish and other fish contaminated in their environment
Fecal (sewage) contamination of water  pathogen uptake by filter‑feeding on waterborne particles
Fish and shellfish naturally colonized by aquatic pathogens
Vibrio cholerae in copepods, fish and shellfish
Produce contaminated by irrigation with sewage or contaminated water or fertilization with nightsoil (feces) or animal feces.
Soil contaminating plants and animals with bacteria, fungi, etc.

7. Foods Implicated in Foodborne Illness: Meats
Red Meats
High contamination in comminuted and processed meats (e.g., ground beef, sausage)
High surface area, increased contact with processing equipment; increased handling; variety of sources from the animal (organs, trimmings, etc.).
Ex., E. coli O157:H7 outbreaks due to undercooked hamburger
Poultry
High contamination levels in cut‑up poultry
Increased handling, processing and contact with common equipment
Salmonella and campylobacters are prevalent in some poultry flocks
can contaminate an entire processing plant via equipment and process baths (e.g., chiller tank)
Eggs
Endogenous contamination by Salmonella enteritidis in some flocks
Time and temperature abuse leads to proliferation in the egg
Raw/undercooked eggs a source of exposure and infection

8. Foods Implicated in Foodborne Illness: Fish
Contamination depends on type of seafood,quality of harvest water and amount of processing, handling and storage.
Bivalve mollusks (oysters, clams, mussels, etc.); filter feeders
Accumulate enteric pathogens from fecally contaminated waters
Acquire high levels of vibrios from their environmental waters
Crustaceans (e.g., crabs)
Acquire some pathogens by feeding on mollusks
Acquire high levels of vibrios from their water environment
Vibrio levels can increase during handling, processing and storage, especially if temperatures are too high.
Fin fish
Outer surface and epithelial lining (e.g., gut) contamination by enteric microbes in fecally contaminated waters;
Contamination during processing (e.g., filleting).
Endogenous contamination:
Ex:: Diphyllobothrium latum; fish tapeworm; anemia; undercooking

9. Other Foods Implicated in Foodborne Illness
Produce (fruits and vegetables)
fecal contamination in irrigation water and other fecal sources (animal droppings, birds, etc.)
inadequate or unsanitary picking, washing or processing.
Dairy Products
In developed countries milk and related dairy products are usually made from pasteurized milk.
Raw milk and products (e.g., cheeses) made from unpasteurized milk are high risk of bacteria contamination
salmonella, campylobacter, brucella, yersinia, listeria,).
Unpasteurized fruit juices and other beverages
fecal contamination from animal and human sources
Deli, "Fast" and Restaurant Foods
salads, sandwiches, other fast, deli or restaurant foods
become fecally contaminated during preparation and handling
Cereal and Grain: inadequate storage of cooked rice/grain

10. Methods to Control Fecal Contamination of Foods - I
Prevent exposure to fecal contamination in the environment, after harvest or during processing, preparation and handling
Maintain sanitation in the environment:
harvest shellfish only from waters that are not fecally contaminated;
irrigate fruits and vegetables with non‑fecally contaminated water.
fertilize fruits and vegetables with uncontaminated fertilizers.
Maintain uninfected herds and flocks of animals
Immunize animals against infectious diseases:
Brucella abortus: brucellosis from cattle; raw milk/dairy products
Colonize animals with harmless microflora:
Colonize baby chicks with harmless bacteria competitive to Salmonella
Destroy animals harboring pathogens:
Bovine Spongiform Encephalopathy (BSE; “mad cow” disease);
Caused by a prion able to infect humans (neural tissue in meat)

11. Methods to Control Fecal Contamination of Foods - II
Maintain adequate hygiene and sanitation during harvest, processing, storage and distribution.
Source control: use of non‑fecally contaminated foods and ingredients;
Use clean water for washing, processing, cleaning and worker hygiene;
Adequate human and food waste treatment and disposal facilities
Plant and equipment sanitation: clean, sanitize, etc.
Personal hygiene, food handling practices and employee health (education, training and policies).
Criteria and standards and guidelines for fecal contamination (pathogens and microbial indicators).
Inspection, monitoring and surveillance (product testing)

12. Hazard Analysis/Critical Control Points (HACCP)
A program of process control to (1) identify microbial hazards, (2) identify the most vulnerable (critical) sites or steps in the process and (3) implement an in‑house monitoring system for quality assurance and hygiene.
Incorporates elements of:
(i) education and training,
(ii) ingredient or commodity control,
(iii) process control,
(iv) inspection, and
(v) microbiological and related surveys
Design and implement on a commodity-specific and production facility-specific basis

13. Methods to Control Fecal Contamination of Foods
Prevention: keep enteric microbes out
Remove enteric microbes:
identify and remove contaminated food items and ingredients
wash to remove contaminants filtration or other physical separation methods
depurate or relay live shellfish.
Use of heat
sterilize
disinfect (e.g., pasteurize and cook to destroy pathogens
Use of cold and freezing
cold storage and freezing to prevent proliferation
Drying, dehydration and intermediate-moisture processing
Chemical treatments: disinfect and sanitize
Irradiation: UV and gamma (ionizing) radiation

14. Heat and Thermal Treatment
Effects of heat vary with:
food composition: water, fat, proteins, carbohydrates, salts and pH
organism factors: form, composition, growth stage, age, etc.
Sterilize (or nearly sterilize) foods (destroys all viable microbes)
Heat >100oC; usually uses high pressure and steam;
Typical target temperature is 115‑116oC for about 60 minutes.
Example: Retorting of Canned Foods.
Pasteurization:
Intended to kill pathogens;
Does not sterilize the food;
Often used prior to subsequent cold storage so pathogens or spoilage organisms do not proliferate.
High Temperature‑Short Time Method: 72oC; 15 sec. (milk)
Low Temperature‑Long Time Method: 62.8oC for 30 min.(milk)
Pasteurization times and temperatures for other foods depend on the effects of heat on the food, food composition and the target organisms of interest.

15. Thermal Destruction of Microbes: Thermal Death Time and D Value
Thermal Death Time (TDT): time needed to kill a specified number of organisms at a specified temperature.
D value: time needed to destroy 90% or 1 log10 of organisms at a specified temperature
Assumes first-order (exponential; log-linear) destruction kinetics
Survivors (%)
1--
D value
Time (min.)

16. Drying, Dehydration and Desiccation
Low moisture foods: usually <15% moisture
Intermediate moisture foods (IMF): 15-50% moisture
fruits, cakes, syrups, candies, jams, milks, some meats and cheeses
Sun (natural) drying: often used for fruits
Heat drying (dehydration; desiccation)
Freeze drying (lyophilization; cryophilization)
Condensing or evaporating: reducing moisture in a liquid food; e.g., evaporated or sweetened condensed milk.
Drying destroys some enteric microbes but is not very effective for others.
Inhibitors are often used for dried and IMF foods:
ex.: potassium sorbate and calcium propionate as fungistats

17. Chemical Treatments Preservatives: Disinfectants and sanitizers:
Most are ineffective against viruses and protozoan cysts
most are designed to control certain bacteria and molds.
propionates, sorbates, benzoates and p‑hydroxybenzoates: molds
Nitrates and nitrites (ex., for Clostridia.)
Sulfur dioxide and sulfites
Acetic, lactic and other organic acids
NaCl and sugars
Ethylene and propylene oxides
Disinfectants and sanitizers:
Used to treat (by washing or dipping) certain meats and produce
Chlorine, peroxyacetic acid, ozone, hydrogen peroxide
10s to 100s of mg/l; contact times of seconds to minutes
Organic acids (acetic, lactic and citric) at 2-7%; less effective

18. Food Irradiation Ionizing Radiation (X‑rays and gamma rays)
Becoming more widely used.
Gamma radiation from Co-60 and Cs-137 sources)
Effectiveness depends on: organism, composition of the food, temperature, and presence of oxygen
Undesirable changes in foods from excessive radiation: radiolysis of water and other chemical reactions on amino acids, etc..
Doses(approximate) to inactivate 1 log10 of organisms:
vegetative bacteria: 100‑200 Krad
viruses: 500 Krad
Cysts and Spores: 500 Krad
UV Radiation:
Low (monochromatic 254 nm) mad medium (polychromatic)
Used primarily for beverages: water, juices, ciders, etc.

19. Factors Influencing Uptake and Persistence of Enteric Microbes in Shellfish
Type of microbe: viruses are more persistent than bacteria
Type of shellfish: differences among shellfish species and genera
Temperature: uptake and persistence greater at higher temperature (to a limit); at very low and very high temperature, the animals become inactive and do not pump water
Salinity: uptake and persistence greater at higher salinity.
If salinity is low they become inactive and not pump water.
Turbidity: excess causes gill clogging and interferes with activity.
Higher turbidity increases microbial uptake but does not greatly influence elimination (except for some enteric bacteria).
Dissolved oxygen: animals become inactive (suffocate at low DO).
pH: in he physiological has little influence on uptake or elimination)
Other water quality factors: toxic chemicals can interfere with activity
Food supply: little direct effect if it does not change pumping activity
Spawning reduces microbial elimination from shellfish.

20. Monitoring Fecal Contamination in Shellfish and Harvest Waters
Harvest waters and shellfish are monitored for bacterial indicators of fecal contamination
Total coliforms
Fecal coliforms
E. coli
Current bacterial indicators of shellfish microbial quality do not adequately predict the presence and risks of viral contamination of bivalves or their harvest waters
Viruses have been detected in approved shellfish and harvest waters
Viral outbreaks have been detected in approved shellfish and harvest waters

21. Virus Analyses of Shellfish and Growing Waters: Current Status and Future Directions
Develop a reliable viral indicator
F+ coliphages, somatic coliphages, other phages
Simple assay methods
Detect human enteric viruses, esp. HuCVs
Further purify and concentrate; improve methods; then
Detect by: nucleic acid amplification (RT-PCR and PCR), hybridization, restriction fragment length polymorphism (RFLP) and sequencing
Combine cell culture and nucleic acid to amplify and detect (for culturable viruses)

23. % Organisms Remaining

24. Enteroviruses in Oysters and Relationships to Microbial Indicators
Significant
Difference
Geometric Mean Number/100 ml
Chung et al., Water Sci. Technol., 1998

25. Shellfish Depuration and Relaying
Place live bivalve mollusks shellfish in clean flowing seawater
Normal pumping, feeding and related activity rids accumulated microbes
Relaying:
transfer shellfish from contaminated (restricted) waters to uncontaminated natural estuarine waters.
Typical holding times in the clean water are two weeks or longer.
Depuration:
Place restricted shellfish in shore‑based tanks of clean, flowing seawater under controlled conditions for periods of several days
Factors influencing deputation efficiency:
tank geometry and loading (quantity of shellfish per volume of tank),
water quality
temperature

26. Foodborne Disease in the Home
About half of all Salmonella cases result from unsafe handling of food in the home.
Foodborne illness costs the United States $23 billion annually.
Foodborne illness is often mistaken for “the flu, as many of the symptoms are similar:
stomach pain, diarrhea, nausea, chills, fever, and headache.
Many experts believe the kitchen is home to more potentially dangerous bacteria than even the bathroom.

27. Regularly Clean the Kitchen and Other Food Preparation Areas to Reduce Risks of Cross-contamination and Foodborne illness
?Use antibacterial products for added protection in the kitchen to prevent foodborne illness?
Wash hands thoroughly
Clean and sanitize all surfaces frequently

28. Hands Spread Foodborne Pathogens from the Food to Other Places
refrigerator
door handles
hot and cold sink faucets,
dishcloths,
counter-tops,
stove knobs
high chairs
appliances
etc.

29. Sponges Versus Paper Towels
Foodborne bacteria can multiply quickly in kitchen towels, sponges and cloths.
Wash sponges and cloth items in the washing machine or dishwasher frequently to reduce bacteria levels.
For quick treatment, microwave them till very hot to reduce bacteria levels
Paper towels reduce cross-contamination risks
they are disposable, so they less readily spread bacteria if discarded after a single use

30. Cutting Boards: Plastic or Wood
Plastic cutting boards:
less porous
absorb and retain less bacteria than porous wood
Wood cutting boards
more porous
absorb more bacteria, but may actually be antibacterial
After meal preparation, wash cutting board with soap and water and then clean with an antibacterial cleaner or bleach and water mixture.
Always follow the product label's directions.
Plastic and solid wood cutting boards are dishwasher safe.

31. Reducing Foodborne Illness Risks in Food Shopping
Shop only at reputable stores.
Check expiration dates of meats, dairy products, etc.
Select canned foods free of dents and cracks
(bulging lids and cans indicate a food poisoning threat).
Avoid cross-contamination in your shopping cart
do not allow raw meat, poultry or seafood juice to drip on to your other groceries.
Buy perishables last and keep them in the coolest part of your car.
Refrigerate or freeze promptly upon arrival at home.

32. Keeping Foods Clean
Work with clean hands, hair, fingernails, and clothing.
Wash hands with soap and water after using the toilet
Wash hands after smoking or blowing your nose
Wash hands after touching raw meats, poultry & seafoods Avoid using hands to mix foods; use clean utensils
Keep hands away from mouth, nose, and hair.
Cover coughs and sneezes with disposable tissues and wash hands thoroughly afterward.
Avoid using the same spoon more than once for tasting food while preparing, cooking, or serving.
Clean all dishes, utensils, and work surfaces with soap and water after each use esp. if used for raw food
Treat utensils and work surfaces with a solution of 1 tablespoon (about 1 capful) of chlorine laundry bleach to 1
gallon of cool water.

33. Salmonella Infection
Causes an estimated 1.4 million foodborne illnesses/year
From , only 189,304 Salmonella infections (~38,00/year) reported through the National Salmonella Surveillance System
a passive, laboratory-based system.
In the same period, 357 recognized outbreaks of Salmonella infection resulting in 32,610 illnesses were reported through the Foodborne-Disease Outbreak Surveillance System.
These system greatly underestimate the burden of foodborne disease.

34. 4 Steps to Preventing Foodborne Illness
Clean: Wash hands and surfaces often
Separate: Don't cross-contaminate
Cook: Cook to proper temperatures
Chill: Refrigerate promptly

35. Cool Refrigerate/Freeze
Refrigerate uncooked foods
Stored cooked foods in refrigerator
Defrost frozen foods in refrigerator
Set refrigerator for 40-41oF (18oC)
Use uncooked or cooked foods in 1-4 days
Use frozen foods in 1-4 months, depending on food

36. Wash
Wash hands before preparing food and after handling raw meat, poultry and fish
Wash hands after using toilet
Wash cutting boards, utensils and other items in contact with raw meat and poultry
use hot, soapy water
Prevent meat, poultry or its juices from touching other foods or other objects
Wash fresh produce with water or with dilute bleach in water.
Keep inside of refrigerator clean

37. Cook Cook meat and poultry until no longer ping and juices are clear
Cook fish until flaky, not rubbery when cutting
Cook evenly: turn, rotate and/or stir
Cook to safe internal temperatures
Meat and poultry: 165 oF
Refrigerate cooked leftovers immediately
Reheat all leftovers covered at 165 oF or more
Cook eggs until white and yolk are solid, not runny
Avoid foods containing raw eggs: cookie dough, cake batter, etc.

38. Protect Against Foodborne Illness by Following these Food Safety Rules :
Buy pasteurized dairy products (see label) & hard cheeses marked "aged 60 days" (or longer) if made from unpasteurized milk
After handling or cutting raw meat, poultry or seafood, wash your hands, the cutting board, counter, knives, and any other utensils you've used with hot soapy water before using again.
Thoroughly cook meat, poultry and seafood, esp. shellfish.
Cover and store leftover cooked food in refrigerator ASAP.
Reheat all leftovers until steaming hot.
Thoroughly wash raw fruits and vegetables with tap water.
Follow label instructions on products that must be refrigerated or that have a "use by" date.
Keep the inside of the refrigerator and counter tops clean.

39. Consumer Education and Outreach Programs in Food Safety
Government:
US Department of Agriculture
US Food and Drug Administration
UC Centers for Disease Control and Prevention
Private Sector
Consumer and Public Interest Groups
Partnerships and Consortia
The Partnership for Food Safety Education