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BVetMed - Additional content (Year 4) > Foodborne Dz And Outbreak Investigation > Flashcards

Foodborne Dz And Outbreak Investigation Flashcards

1
Q

Origins of food borne hazards

A

> e.coli
- present in water, cattle act as reservoir (manure infects)
campylobacter
- in environment introduced in broilers houses
listeria
- envirment contamination (steel pipes drains etc.)

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2
Q

Give egs. Foodborne illness caused by biological, chemical and physical hazards

A

> Biological
- animal, human or envirment origins
Chemical and physical eg. Dioxins and mycotoxins transmissable by food of animal origin

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3
Q

Which food borne dz has highest mortality rates?

A

Listeria (proportionally)

> but the public health impact is a function of the fatality rate and the incidence of infection

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4
Q

Which is the highest number of cases impact pathogens of foodborne dz (UK)

A
  • campylobacter over half

- norovirus

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5
Q

Outline FSA priority list of foodborne diseae from the 2010-2015 action plan

A 
> campylobacter 
> listeria
> e. Coli
> salmonella 
> norovirus 
> clostridium  perfringens
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6
Q

Which food group has the highest risk of food borne disease per serving

A

Poultry (compared to cooked vegetables)

  • eggs
  • red meat
  • sea food
  • milk
  • other dairy lowest risk
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7
Q

Sources of campylobacter

A
  • endemic in animals (poultry, cattle, sheep, pigs)

- sources food and nonfood eg. Untreated water

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8
Q

Clinical signs campylobacter

A
  • incubation period 2-5d
  • d+ and abdo pain
  • self limiting in 10d
  • rare sequalae : Guillan Barre syndrome
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9
Q

How does seasonal incidence of campylobacter change ?

A
  • seasonal peak late spring and summer (maybe d/t flies? Not known)
  • mirrored by humans (sometimes this proceeds the poultry rise!!)
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10
Q

Aim of FSA 2010-2015 wrt campy?

A

Decrease numbers of highly contaminated chickens from 27% to 10%
> hasn’t happened!!!

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11
Q

How can campylobacter tried be managed?

A
  • NB even doing these things risk of campy infection is VERY HIGH*
    > on farm
  • biosecurity fly screen, feed and water additive, vax, genetic resistance
    > farm level management or husbandry
  • thinning or partial depopulation strong risk factor for flock colonisation
    > slaughter and processing
  • campy+ flocks cross contaminate at abbattoir , slaughter last
    > freezing/hot water/chemical decontamination
    > consumer
  • cook properly, avoid cross contamination
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12
Q

Second most common cause of food borne dz in UK?

A

Salmonella

  • and most common pathogen causing food borne OUTBREAKS across the WHOLE EU
  • cf. campy which causes sproadic cases NOT outbreaks
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13
Q

Trend of salmonella case

A

Decreasing but still high (s. Enteridis poultry)

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14
Q

Clinical signs salmonella

A
  • incubation period 12-48hrs
  • VD+ abdo pain and fever
  • self limiting 3-5d
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15
Q

Which sero are of salmonella exist?

A
  • s. Dublin cattle
  • s. Diarizonae sheep
  • s. Typhimurium pigs
    > s. Enteridis POULTRY most successful cause of decrease in salmonella cases
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16
Q

Where is salmonella a hazard?

A
  • raw egg (mayonnaise, ice cream)
  • eggs contaminated before shell is formed
  • pasteurisation destroys
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17
Q

Hazards milk and milk produce

A
  • TB
  • Brucella
  • Salmonella
  • Campylobacter
  • Listeria monocytogenes
  • Staph aureus
  • Bacillus spp.
18
Q

Which hazards in raw milk are destroyed by heat treatment

A
  • TB
  • brucellosis
  • salmonella
  • campylobacter
19
Q

Give 3 pathogens that may pose a risk despite heat tx of milk

A
  • listeria monocytogenes
  • staphylococcal aureus
  • bacillus spp.
20
Q

Sources listeria monocytogenes

A
  • infected animals
  • environment
  • silage
  • BIOFILMS in food processing environment
21
Q

Infective dose of listeria and risk foods

A

> low

  • raw milk
  • chilled ready to eat foods (long shelf life when chilled, no need to cook before eating)
  • sandwiches
  • pate
  • soft mould rippened cheese
  • cooked sliced meats
  • smoked salmon
22
Q

Does heat Tx destroy listeria?

A

Not all but enough to render it safe

- post-pasteurisation contamination main risk

23
Q

Listeria Clinical signs and Risk management listeria monocytogenes

A

> CS
- incubation period LONG ~1month
-non-invasive: flu like symptoms/asymptomatic
- invasive: abortion, meningioencephalitits in children elderly and immunocompromised
risk management
- only causes illness in limited subset of population (target at risk groups)
- industry compliance and enforcement (listeria widespread in environment but need to minimise growth to harmful levels)
- consume food in date

24
Q

Why is bacillus cereus a risk

A
  • produces spores that survive pasteurisation
  • it grows at 5* and produces a toxin
    > need proper refrigeration
  • usually spoils milk before toxin produced so not often consumed
25
Q

Why does staph aureus cause problems?

A
  • post pasteurisation contamination from asymptomatic carrier worker people
  • staphylococcal enterotoxins formed in food are consumed
26
Q

Hazards in pork

A
  • salmonella
  • yersinia enterocolitica
  • hepatitis e
  • campy
  • trichinella
  • aeromonas (spoilage pathogen)
27
Q

Yersinia in pigs

A
  • very common in pigs asymptomatic
  • undercooked pork
  • other vehicles untreated water and unpasteurised milk
    > in humans usually resolves on its own but more severe young and elederly
28
Q

How has hepatitis E incidence changed? Likely source?

A
  • massively increased numbers native humans over last few years
  • Pigs very often carriers
  • ^ risk of hepatitis E with processed pork consumption
  • makes over 45 years old over represented
29
Q

Hazards in beef

A 
> e.coli 0157 
- feacal contamination mince meat 
> aeromonas (spoilage) 
> prions (BSE) 
> clostridium perfringens
30
Q

E. Coli 0157 clinical signs and infective dose needed

A
  • low dose needed
  • VD+ abdo pain
  • haemorrhage colitis
  • most severe children and the elderly
  • haemolytic uraemia syndrome(HUS)
  • renal failure and death
31
Q

Vehicles for E.coli infection and therefore risk management strategies

A
  • undercooked mince meat
  • direct contact open farms
  • prevalence in cattle up to 20%
    > prevention
  • farm biosecurity
  • slaughter hygiene
32
Q

Hazards in fish and shellfish

A

> hepatitis A
norovirus
- raw seafood eg. esp oysters (virus not destroyed as not cooked)
vibrio spp.
- raw seafood eg. esp oysters (virus not destroyed as not cooked)
environmental contaminants

33
Q

why do shellfish pose a health risk?

A
  • filter large volumes of water, accumulate pathogenic viruses and bacteria
34
Q

Risk management shell fish

A
  • relaying (moved to clean area of water for min 2 months before harvest)
  • depuration (placed in tanks of clean re-circulating sea water tx with UV radiation min 42hrs)
    > this is v effective for bacteria, less so for viruses
35
Q

Hazards in honey

A
  • clostridium botulinum
  • environmental contaminants
  • antimicrobial residues
36
Q

Why should children not consume honey?

A

Potential for clostridial botulinum spores to grow in intestinal tract of very young children

37
Q

Are all foodborne dz zoonotic?

A
  • not all foodborne illness is zoonotic

- not all zoonoses are foodborne

38
Q

Infectious dose, pathophysiology of botulism

A

> extremely potent low dose needed

  • c. botulinum ubiquitous in soil, sediments, water etc.
  • growth of pathogen ANAEROBIC conditions only
  • home canned or fermented stuff
39
Q

Clinical signs botulism in humans. Tx?

A
  • incubation time 12-36hrs
  • tx: antitoxin
  • can be fatal
    > infant botulism if bacteria colonises large intestine
40
Q

Give 2 “processing” hazards

A

> staph aureus
- on food handlers
- produces toxin
- high risk products: custard, whipped cream
clostridium perfringen s
- present in environment and raw meat
- inadequate temperature control during cooking -> spores can germinate and bacteria can grow
- high risk products: stew, long, slow cooking

41
Q

egs. chemical hazards in food

A
  • heavy metals
  • halogenated hydrocarbons
  • insecticides
  • fertilisers
  • hormone like GP/antimicrobial GP
  • biogenic amines
  • MYCOTOXINS
  • meat conservation
  • packaging
    > see table for more egs./
42
Q

Which hazards can accumulate in the food chain? How are these monitored/controlled?

A
  • heavy metals, halogenated hydrocarbons, insecticides (DDT)
  • toxicity mostly chronic (carcinogens, teratogens)
    > max levels (WHO/FAO) monitored by UK FSA and DEFRA
    > recall of products if higher than max allowed (eg. Dioxins in pork)
    > VMD statutory residue surveillance for vet medicines and environmental residues

BVetMed - Additional content (Year 4) (34 decks)

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