Food-borne infections and toxins Flashcards
(51 cards)
What is the #1 cause of food-borne disease?
typhoid (vaccine not very effective still although more effective than it used to be)(Salmonella enterica)
What is the #1 water-borne disease?
cholera (Vibrio cholerae)
How are persistent food-borne diseases largely transmitted?
from animals via food
What is best way of not getting food-borne enteritis?
- cook food properly
- some foods develop toxins on standing after cooking
- cooked food can become contaminated from raw food or faeces
What are the 5 primary agents causing food-borne disease?
- Campylobacter
- Salmonella
- Listeria
- E.coli
- Norovirus
Name less important causes of food-borne illness and their most likely sources.
- S. aureus (nasal secretion)
- Bacillus cereus (rice)
- Clostridium perfringens type A (faeces)
- Clostridium botulinum (soil and faeces)
- Vibrio parahaemolyticus (shellfish)
- TSE (bovine neural tissues)
Why are steak burgers more likely to transmit food-borne disease than pieces of steak?
- steak can get contaminated on outside of meat, inside muscle tissue can contain spores of bacteria (not harmful to humans - blackleg) but
- minced meat is mixture of ‘inside and outside meat’
What are the proportions of the main 5 pathogens in food (burden in terms of cases)
- campylobacter (60%)
- Norovirus (37%)
- Salmonella (3%)
- Listeria and E.coli 0157 (STEC) negligible amounts
What causes teh most hospital admissions?
> 90% hospital admissions are caused by campylobacter.
- almost all cases of E.coli and listeria end up in hospital
- norovirus causes hospitalisation if concurrent disease.
What causes most deaths with food-borne illness?
- campylobacter 30%
- salmonella (20% - i.e. lots of people who get salmonella die)
- E. coli and listeria (relatively high % cases die)
What was total 2011 cost of foodborne disease in england and wales
1564 million
Trend - campylobacter
- decreased in early 2000s, has been increasing since about 2005
Outline campylobacter jejuni (poultry) and C. coli (pigs)
- curved gram negative rod
- very small
- microaerophilic
- can grow at 42 degrees (thus thermophilic)
- endemic/enzooti in animls
- carried by birds (especially poultry) and many mammals
- zoonotic
Diagnosis - campylobacter
- culture of faecal sample (gold standard) other methods do exist
- blood agar with AB selection
- 48 hours
- 42 degrees microaerophilic atmosphere
- demonstrate curved gram negative rods
Outline campylobactr disease
- incubation 2-5 days
- colonises the SI and enteritis
- CS: diarrhoea, vomiting, stomach pains/cramps, fever (d/t invasion and signalling to innate immune system), unwell
- commonest food poisoning in UK
How Campylobacter infection is acquired?
- most raw poultry
- raw meat
- infected pets and farm animals
- chickens are regularly colonised
- factors processing of broilers
- contamination of (inside of) carcass
- freezing allows survival inside carcass
What are the different Campylobacter species?
- Campylobacter jejuni (poultry meat)
- Campylobacter coli (pigs, pork meat)
- Campylobacter upsaliensis (dogs)
T/F: cooking always kills Campylobacter
True
T/F: water baths for poultry are trying to be removed
True -
T/F: ice within inside of incompletely defrosted poultry still contains Campylobacter. Then cooking allows organism to grow –> campylobacter disease
True
What temperature can listeria grow
8-10 degrees (fridges normally fluctuate between 4-10 degrees –> listeria can grow slowly)> leaving milk out on side allows listeria to grow! except pasteurisation prevents listeria being in milk in the first place)
Source of human listeriosis
- contaminated raw meat
- unpasteurised milk
- cheese made using unpasteurised milk
- foods containing raw veegetables (especially organic vegetables grown in well-manured soils)
Number of cases of human listeriosis in UK
200-250/year but can be nasty
Outline listeria transmission routes
Insert diagram
