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ENVR 191 PowerPoint Presentation

ENVR 191

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ENVR 191

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

  2. 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.

  3. 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

  4. 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

  5. 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

  6. 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)

  7. 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)