Foodborne Dz And Outbreak Investigation Flashcards Preview

PMVPH 4th Year > Foodborne Dz And Outbreak Investigation > Flashcards

Flashcards in Foodborne Dz And Outbreak Investigation Deck (42):
1

Origins of food borne hazards

> 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.)

2

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

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

3

Which food borne dz has highest mortality rates?

Listeria (proportionally)
> but the public health impact is a function of the fatality rate and the incidence of infection

4

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

- campylobacter over half
- norovirus

5

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

> campylobacter
> listeria
> e. Coli
> salmonella
> norovirus
> clostridium perfringens

6

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

Poultry (compared to cooked vegetables)
- eggs
- red meat
- sea food
- milk
- other dairy lowest risk

7

Sources of campylobacter

- endemic in animals (poultry, cattle, sheep, pigs)
- sources food and nonfood eg. Untreated water

8

Clinical signs campylobacter

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

9

How does seasonal incidence of campylobacter change ?

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

10

Aim of FSA 2010-2015 wrt campy?

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

11

How can campylobacter tried be managed?

* 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

12

Second most common cause of food borne dz in UK?

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

13

Trend of salmonella case

Decreasing but still high (s. Enteridis poultry)

14

Clinical signs salmonella

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

15

Which sero are of salmonella exist?

- s. Dublin cattle
- s. Diarizonae sheep
- s. Typhimurium pigs
> s. Enteridis POULTRY most successful cause of decrease in salmonella cases

16

Where is salmonella a hazard?

- raw egg (mayonnaise, ice cream)
- eggs contaminated before shell is formed
- pasteurisation destroys

17

Hazards milk and milk produce



- TB
- Brucella
- Salmonella
- Campylobacter
- Listeria monocytogenes
- Staph aureus
- Bacillus spp.

18

Which hazards in raw milk are destroyed by heat treatment

- TB
- brucellosis
- salmonella
- campylobacter

19

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

- listeria monocytogenes
- staphylococcal aureus
- bacillus spp.

20

Sources listeria monocytogenes

- infected animals
- environment
- silage
- BIOFILMS in food processing environment

21

Infective dose of listeria and risk foods

> 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

Does heat Tx destroy listeria?

Not all but enough to render it safe
- post-pasteurisation contamination main risk

23

Listeria Clinical signs and Risk management listeria monocytogenes

> 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

Why is bacillus cereus a risk

- 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

Why does staph aureus cause problems?

- post pasteurisation contamination from asymptomatic carrier worker people
- staphylococcal enterotoxins formed in food are consumed

26

Hazards in pork

- salmonella
- yersinia enterocolitica
- hepatitis e
- campy
- trichinella
- aeromonas (spoilage pathogen)

27

Yersinia in pigs

- 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

How has hepatitis E incidence changed? Likely source?

- 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

Hazards in beef

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

30

E. Coli 0157 clinical signs and infective dose needed

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

31

Vehicles for E.coli infection and therefore risk management strategies

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

32

Hazards in fish and shellfish

> 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

why do shellfish pose a health risk?

- filter large volumes of water, accumulate pathogenic viruses and bacteria

34

Risk management shell fish

- 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

Hazards in honey

- clostridium botulinum
- environmental contaminants
- antimicrobial residues

36

Why should children not consume honey?

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

37

Are all foodborne dz zoonotic?

- not all foodborne illness is zoonotic
- not all zoonoses are foodborne

38

Infectious dose, pathophysiology of botulism

> 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

Clinical signs botulism in humans. Tx?

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

40

Give 2 "processing" hazards

> 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

egs. chemical hazards in food

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

42

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

- 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