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PMVPH (round 2) > Food-borne risks by commodity > Flashcards

Food-borne risks by commodity Flashcards

1
Q

Outline origin of Listeria

A

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

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2
Q

Give possible origins of E. coli 0157

A

contamination of vegetables from water exposed to cattle faceces

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3
Q

Outline possible origin of Campylobacter or Salmonella

A

linked to sick food handlers

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4
Q

Which foodborne dz has highest mortality rate?

A

listeria monocytogenes

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5
Q

List examples of biological food borne hazard by category

A

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

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6
Q

What does public health impact depend on?

A
  • total # cases
  • severity of cases (# hospitalised, deaths)
  • overall L.monocytogenes, E.coli 0157, Salmonella, Norovirus
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7
Q

What are the 2 biological hazards in chicken meat?

A
  • Campylobacter

- Salmonella (S. enteritidis)

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8
Q

Main source of human campylobacteriosis

A

Broiler meat

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9
Q

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

A

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

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10
Q

CS - campylobacter in humans

A
  • 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)
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11
Q

When is there a seasonal peak in Campylobacter?

A

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

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12
Q

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

A

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

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13
Q

Methods - reduce campylobacter

A
  • 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
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14
Q

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

A

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

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15
Q

CS - salmonella

A
  • incubation 12-48h
  • diarrhoea, vomiting, abdominal pain
  • fever
  • self-limiting within 3-5d
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16
Q

Vehicles - salmonella

A
  • poultry, eggs, deserts (products made with raw eggs - mayonnaise, ice cream)
  • 4-5% chicken contaminated at retail (not current estimates)
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17
Q

What salmonella spp cause dz in livestock?

A
  • Cattle: S. dublin
  • Sheep: S. diarizonae
  • Pigs: S. typhimurium
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18
Q

SOurces - listeria monocytogenes

A
  • infected animals
  • environment
  • silage
  • biofilms in food processing environment
  • low infective dose
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19
Q

Vehicles - listeria monocytogenes

A
  • raw milk

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

20
Q

CS - listeria monocytogenes - humans

A
  • incubation typically 3-4w, can be up to 90 days
  • non-invasive (flu-like symptoms, often asymptomatic)
  • invasive: abortion, meningoencephalitis in children/ elderly/ immunocompromised
21
Q

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

A
  • 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)
22
Q

Outline Bacillus cereus in milk and milk products

A
  • produces spores that survive pasteurisation
  • grows at 5 degrees
  • produces toxin
23
Q

Ways to minimise risk of B.cereus

A
  • proper refrigeration

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

24
Q

Outline S.aureus food poisoning

A
  • 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.
25
Q

List hazards in pork

A
  • Salmonella
  • Yersinia enterocolitica
  • Hepatitis E
  • Campylobacter
  • Trichinella
  • Aeromonas (spoilage pathogen)
26
Q

Describe Yersinia enterocolitica

A
  • v common in pigs, normally causes little or no dz

- from USA

27
Q

Vehicles - Yersinia enterocolitica

A
  • pork (undercooked pork products)

- others: untx water, unpasteurised milk

28
Q

Yersinia in people

A
  • usually resolves on own

- can be more severe in young and elderly

29
Q

Outline hepatitis E

A
  • 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%
30
Q

Highest risk category - hepatitis E

A
  • male humans >45 years old (overrepresented)

- unknown why

31
Q

What hazards are in beef?

A
  • E.coli 0157
  • aeromonas (spoilage pathogen)
  • prions (BSE)
  • Clostridium perfringens
32
Q

Vehicle - E.coli 0157

A
  • undercooked minced meat

- direct contact with open farms

33
Q

CS - human E.coli 0157

A
  • low infection dose ( haemolytic uraemic syndrome (HUS), renal failure, death
34
Q

Contrast E.coli and Salmonella

A

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

35
Q

Hazards - fish and shellfish

A
  • hepatitis A virus
  • norovirus
  • Vibrio spp (raw seafood - oysters)
  • environmental contaminants
36
Q

Risk management - norovirus

A

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
37
Q

List hazards in honey

A
  • Clostridium botulinum
  • Environmental contaminants
  • Antimicrobial residues
38
Q

Outline botulism

A
  • extremely potent
  • C. botulinum: ubiquitous in soil, sediments, water
  • growth of pathogen required under anaerobic conditions
39
Q

Name 2 ‘process hazards’

A
  • S. aureus

- C. perfringens

40
Q

Give examples of chemical hazards in foods

A
  • 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
41
Q

How do shellfish get contaminated?

A

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

42
Q

Vehicles - botulism

A
  • home-canned vegetables, meat, fish

- fermented bean, fish

43
Q

Describe clinical botulism in humans

A
  • incubation time 12-36h
  • tx: antitoxin
  • fatal outcome possible
44
Q

Describe S.aureus as a ‘process hazard’

A
  • intoxication
  • common source of bacteria are food handlers
  • bacteria contaminates product and produces toxin
  • high risk products: custards, whipped cream
45
Q

Describe C. perfringens as a ‘process hazard’

A
  • 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
46
Q

What hazards accumulate in the food chain?

A
  • 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.
47
Q

What surveillance does the VMD do?

A

for veterinary medicines and environmental residues

PMVPH (round 2) (45 decks)

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