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Flashcards in Food-borne risks by commodity Deck (47):

Outline origin of Listeria

biofilms in drains, floors or stainless steel surfaces in cheese plant


Give possible origins of E. coli 0157

contamination of vegetables from water exposed to cattle faceces


Outline possible origin of Campylobacter or Salmonella

linked to sick food handlers


Which foodborne dz has highest mortality rate?

listeria monocytogenes


List examples of biological food borne hazard by category

ANIMAL: Brucella, Campylobacter, E. coli 0157, Yersinia spp, Listeria monocytogenes, Mycobacterium sp, Salmonella, BSE/vCJD, Taenia spp, Toxoplasma spp, Trichinella spp, Vibrio vulnificus
HUMAN: Hepatitis A, rotavirus, norovirus, Salmonella spp, Shigella sp, S. aureus, Vibrio cholerae
ENVIRONMENT: Bacillus spp, Clostridium sp, Listeria spp, Mycotoxins, Marine biotoxins


What does public health impact depend on?

- total # cases
- severity of cases (# hospitalised, deaths)
- overall L.monocytogenes, E.coli 0157, Salmonella, Norovirus


What are the 2 biological hazards in chicken meat?

- Campylobacter
- Salmonella (S. enteritidis)


Main source of human campylobacteriosis

Broiler meat


T/F: campylobacter is endemic in animals (poultry, cattle, sheep and pigs)

True (sources include food and non-food such as untreated water). Mainly found in poultry, also red meat, raw milk, untreated water.


CS - campylobacter in humans

- low infectious dose
- incubation period 2-5d
- diarrhoea
- abdominal pain
- self-limiting within 10d
- rare sequelae (Gillan-Barre syndrome = serious autoimmune condition that has been associated with campylobacteirosis)


When is there a seasonal peak in Campylobacter?

late spring and summer (humans and poultry). Most likely an effect of environmental conditions. Raise in human cases sometimes precedes raise in chickens


How will a decrease in the highest level Campylobacter contamination from 27% to 10% in 2015 affect human Campylobacter cases?

estimated to reduce Campylobacter food poisoning by 30% (30,000 cases/year)


Methods - reduce campylobacter

- ON FARM: biosecurity (fly screens), feed and water additives that reduce risk of colonisation, vaccination, genetic resistance.
- MANAGEMENT/HUSBANDRY: thinning or partial depopulation has been identified as a strong risk factor for flock colonisation
- SLAUGHTERING AND PROCESSING: Campylobacter positive flocks --> contaminated chicken products (from same bird and cross-contamination). Logistic slaughter (campylobacter negative flocks slaughtered first).
- Freezing, treating with hot water, chemical decontamination
- ROLE OF CONSUMER: adequate cooking and avoid cross contamination


What is the second commonest cause of foodborne illness across the EU?

- generally decreasing trend, but still most common pathogen causing food-borne outbreaks across EU (S. enteritidis = poultry)


CS - salmonella

- incubation 12-48h
- diarrhoea, vomiting, abdominal pain
- fever
- self-limiting within 3-5d


Vehicles - salmonella

- poultry, eggs, deserts (products made with raw eggs - mayonnaise, ice cream)
- 4-5% chicken contaminated at retail (not current estimates)


What salmonella spp cause dz in livestock?

- Cattle: S. dublin
- Sheep: S. diarizonae
- Pigs: S. typhimurium


SOurces - listeria monocytogenes

- infected animals
- environment
- silage
- biofilms in food processing environment
* low infective dose


Vehicles - listeria monocytogenes

- raw milk
- chilled ready to eat food (prepacked sandwiches, pate, soft mould-ripened cheese, cooked sliced meats, smoke salmon)


CS - listeria monocytogenes - humans

- incubation typically 3-4w, can be up to 90 days
- non-invasive (flu-like symptoms, often asymptomatic)
- invasive: abortion, meningoencephalitis in children/ elderly/ immunocompromised


How is the risk of L.monocytogenes in milk reduced?

- WHO states: pastuerisation is a safe process which reduces the # of L.monocytogenes occurring in raw milk to levels that don't pose an appreciable risk to human health
- ensure proper pasteurisation
- avoid post-pastuerisation contamination (Listeria can thrive in cool and damp food processing environments such as floor drains)
- consumer behaviours
- provision of food to vulnerable groups (especially as many aren't responsible for meeting their own food needs)
- industry compliance/enforcement (target high risk businesses, prevent contamination from equipment and the environment and prevent growth to dangerous levels through product formulation and shelf-life restricion)


Outline Bacillus cereus in milk and milk products

- produces spores that survive pasteurisation
- grows at 5 degrees
- produces toxin


Ways to minimise risk of B.cereus

- proper refrigeration
- dairy products normally spoil before B.cereus contamination is sufficient to cause illness


Outline S.aureus food poisoning

- d/t enterotoxins formed in the food
- outbreaks associated with cheese, when milk was contaminated after pasteurisation
- food handlers can be asymptomatic carriers of S.aureus.


List hazards in pork

* Salmonella
* Yersinia enterocolitica
* Hepatitis E
- Campylobacter
- Trichinella
- Aeromonas (spoilage pathogen)


Describe Yersinia enterocolitica

- v common in pigs, normally causes little or no dz
- from USA


Vehicles - Yersinia enterocolitica

* pork (undercooked pork products)
- others: untx water, unpasteurised milk


Yersinia in people

- usually resolves on own
- can be more severe in young and elderly


Outline hepatitis E

- increasing # human cases
- processed pork products as risk factor
- high prevalence in pigs in UK, seroprevalence as 92.8% and prevalence infection is 5.8%


Highest risk category - hepatitis E

- male humans >45 years old (overrepresented)
- unknown why


What hazards are in beef?

* E.coli 0157
- aeromonas (spoilage pathogen)
- prions (BSE)
- Clostridium perfringens


Vehicle - E.coli 0157

- undercooked minced meat
- direct contact with open farms


CS - human E.coli 0157

- low infection dose ( haemolytic uraemic syndrome (HUS), renal failure, death


Contrast E.coli and Salmonella

Infection (e.coli) rare c.f. campylobacter but dz can be severe for affected individuals


Hazards - fish and shellfish

* hepatitis A virus
* norovirus
- Vibrio spp (raw seafood - oysters)
- environmental contaminants


Risk management - norovirus

Options before and after harvesting:
- RELAYING: shellfish are harvested from a contaminated area and moved to a clean area for at least 2 months
- DEPURATION: shellfish are placed in tanks of clean recirculating seawater tx by UV radiation for at least 42h. More effective in removing bacteria than norovirus


List hazards in honey

- Clostridium botulinum
- Environmental contaminants
- Antimicrobial residues


Outline botulism

- extremely potent
- C. botulinum: ubiquitous in soil, sediments, water
- growth of pathogen required under anaerobic conditions


Name 2 'process hazards'

- S. aureus
- C. perfringens


Give examples of chemical hazards in foods

- INDUSTRIAL POLLUTANTS: heavy metal, halogenated hydrocarbons (e.g. dioxins)
- AGRICULTURAL CHEMICALS: insecticides, herbicides, fungicides, fertilisers
- GROWTH PROMOTERS: hormone-like GP, antimicrobial-like GP (both banned in EU)
- VET MEDS: antimicrobials, antiparasitics
- NATURALLY OCCURING TOXINS: biogenic amines, mycotoxins, algal toxins, plant toxins
- FOOD ADDITIVES: sensory additives, meat conservation, packaging


How do shellfish get contaminated?

faecal material from sewage and surface water can contaminate shellfish production areas where oysters and other shellfish which filter large volumes of water can accumulate pathogenic viruses and bacteria


Vehicles - botulism

- home-canned vegetables, meat, fish
- fermented bean, fish


Describe clinical botulism in humans

- incubation time 12-36h
- tx: antitoxin
- fatal outcome possible


Describe S.aureus as a 'process hazard'

- intoxication
- common source of bacteria are food handlers
- bacteria contaminates product and produces toxin
- high risk products: custards, whipped cream


Describe C. perfringens as a 'process hazard'

- intoxication
- present in environment and raw meat
- inadequate temperature control during cooking may allow spores to germinate and bacteria to grow
- high risk products: stew, long, slow-cooking


What hazards accumulate in the food chain?

- heavy metals, halogenated hydrocarbons, inseciticides (DDT)
- toxicity mostly chronic (carcinogen, teratogen)
- recommended minimum levels (WHO/FAO) monitored by UK FSA and DEFRA. Recall if higher levels found.


What surveillance does the VMD do?

for veterinary medicines and environmental residues