ENVR 191 Food Safety and Foodborne Disease Lecture 1 December 3, 1999 Mark D. Sobsey.
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Transcript of ENVR 191 Food Safety and Foodborne Disease Lecture 1 December 3, 1999 Mark D. Sobsey.
ENVR 191
Food Safety and Foodborne Disease
Lecture 1
December 3, 1999
Mark D. Sobsey
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.
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
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
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
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)
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)