Foodborne zoonoses and control Flashcards
(44 cards)
1
Q
What is zoonoses?
A
- infections/ disease that are naturally transmitted between animals and humans
- 60% pathogens = zoonotic
- 75% of emerging infectious diseases have roots in zoonotic pathogens
2
Q
What are FBDs?
A
- food borne disease
- acute illnesses that are associated with the recent consumption of food
- contain a pathogen/ toxin
3
Q
What is the worldwide impact of foodborne disease?
A
- 2.5 million deaths/year from diarrhoeal disease
- 1.4 million cases of salonella - USA
- $35 billion loss to economy
- death of HIV patients
4
Q
Difference between foodborne infection and intoxication?
A
- infection - caused by an infection of bacteria etc
- intoxication - toxin - more rapid onset
5
Q
What are foodborne infections caused by?
A
- pathogenic microorganisms infecting food, entering the body and the reaction of the body tissues to the pathogen
- long incubation periods
- fever
6
Q
`Symptoms of food borne infection?
A
- diarrohea
- fever
- sweating
- cramps
- nausea
- vomiting
- dehydration
7
Q
What are the different types of food borne infections?
A
- bacterial e.g. Salmonella, E.coli, Listeria
- virus e.g. Hep A
- Mycotic e.g. Candida spp
- Parasitic - toxoplasma, protozoa, roundworms, tapeworms
8
Q
Properties of Salmonella?
A
- G-ve
- rod shaped
- anaerobic
9
Q
What are the 2 species in the genus (salmonella)
A
- S.enterica
- S.bongori - cold blooded
10
Q
How many serovars does S.enterica have?
A
- 2,500
11
Q
What are the 3 most common Salmonella causes of infections?
A
- S.enteritidis
- S. tymphimurium
- S. Dublin
12
Q
Incubation period of Salmonella?
A
- 12-36 hours
13
Q
How many organisms per gram do you need of Salmonella to cuase infection?
A
- 1,000 -> 1,000,000
14
Q
How are Salmonella killed?
A
- commercial pasteurisation - 85 degrees for 15 mins/ 4 degrees
- not killed by freezing/ chilling carcasses
- survive in moist earth - 1 year
- in dry earth - 16 months
15
Q
WHere do most outbreaks of salmonella come from?
A
- eggs (50.5%)
16
Q
How are developing eggs infected with salmonella?
A
- transovarian transmission
17
Q
What are the properties of Campylobacter and which are the important human pathogens?
A
- thermophilic - 41/42 degrees
- microaerophilic
- g-ve
- spiral rods
- C.jejuni and C.coli most important
18
Q
Describe Camp outbreaks
A
- more sporadic
- rare
- but have low infectious dose
19
Q
What is the reservoir and incubation period of Camp?
A
- reservoir - intestinal tract of poultry/wild birds
- incubation - 2-5 days
20
Q
Symptoms of Camp?
A
- watery, bloody diarrhoea, nausea, vomiting, headache, fever, abdo pain
- self limiting
- mod to severe
21
Q
In what groups in camp most common?
A
- 65+
- bowel cancer
- proton-pumps
22
Q
What is the reservoirs and symptoms for Listeria?
A
- reservoir = plant material and soil
- 12.7% mortality
- flu like, abortion, septicaemia, meningoencephalitis
- incubation - 3-70 days
23
Q
Properties of E.coli?
A
- only a few pathogenic strains
- O.157 - pathogenic
- linked to poorly cooked beef/ minced
- part of normal gut flora
- can be beneficial - Vit K
24
Q
What does enteroinvasive E.coli cause (EIEC)?
A
- watery diarrhoea (bloody in under 10%)
- abdo pains, nausea, headaches, fever
- self limiting
- 18 hours median
- 10^8 bacterium needed
- lasts 2/3 days
25
What symptoms fo EHEC cause?
* causes haemorrhagic colitis
* bloody diarrhoea
* vomiting
* sometimes fever
* incubation: 3-4 days
* lasts 4-8 days - up to 13
* O157:H7
* hemolytic uremic syndrome (HUS)
26
What do Yersinia and Shigella cause?
* Yersinia - causes enterbacillae yersiniosis
* 4 shigella species - dysentry - can be food borne or person to person
27
How are food borne intoxications characterised?
* short incubation
* no fever
28
Categories of food borne intoxications?
* bacterial
* fungal chemical
* poisonous
* plant
29
How does S.aureus cause foodborne intoxication?
* G+ve, fac. anaerobe, non-spore forming cocci
* enterotoxins formed by the S.aureus (A,B,C,D,E)
30
Nature of the enterotoxins?
* temp stable
* pH stable
* enzyme stable - trypsin, chymotrypsin, renin, pepsin
* not sensitive to irradiation
31
How does S.aureus compete with other micoorganisms?
* poorly
* doesnt grow very well
* so normally in foods where all other microorganisms gone - cooking etc.
32
WHat are the vehicle foods and reservoirs for S.aureus?
* milk
* poultry
* meat
* shellfish
* eggs
* salad cereals
* veg
Reservoirs:
* mucous membranes of nasopharynx and skin
* some in air, water, dust, faeces
33
Disease symptoms of S.aureus?
* nausea, abdo cramps, vomiting, salivation
* 1-6 hours after ingestion of enterotoxin
* lasts for 24-72 hrs
34
Describe Bacillus cereus poisoning
* G+ve, spore forming rod
* produce heat stable toxins:
* emetic
* diaroheal:
* haemolysis BL
* non-haemolytic
35
What are the vehicle foods of Bacillus cereus?
* meat, eggs, dairy products
* cereals - if not cooked and not chilled then spores can germinate, bacteria and toxins produced
* re-heating does not kill toxins
* spores not killed
36
Symptoms of B.cereus in man?
* emetic syndrome
* nausea, vomiting, abdo cramps
* 1-6hrs after diarrohea
* diarrhoeal syndrome
* profuse diarrhoea
* abdo cramps
* tenesmus
* 8-16 hours after ingestion
37
What Clostridiums cause food poisoning?
* G+ve, spore forming rods
* C.perfringens and C.botulinum - severe
* C.difficile - antimicrobial chemotherapy - resistant
38
What is C.perfringens and what does it cause?
* g+ve, anaerobic, spore forming
* soil, dust, sewage, marine sediments
* spores can resist boiling for 4 hours
* ingest vegetative cells
* multiply in intestine and produce CPE
* CPE = heat labile - 60 degrees for 10 mins
* may be pre-formed - 1-2hours after
39
Vehicle foods for C.perfringens?
* meat, fish, veg, chicken, pork, fruits, spices
* cooking = heat resistant endospores
* cooling, warming - endospores germinate
* food cooked one day then eaten the next
* anerobic conditions increase this
* need to reach 10^7/8
40
Symptoms of C.perfringens?
* nausea, vomiting, diarrhoea, cramps
* 6-24 hours
* 1-2 days duration
* needs to reach 5 x 10^8 cells
41
What does C.botulinum cause?
* obligate, anaerobic, spore forming bacillus
* spores -\> vegetative cells -\> enterotoxins
* poorly canned/ bottled - honey
* enterotoxins - blocks synapses - paralysis and death
* Toxins - A, B, E, F, G
* spores - survive 120 degrees
* Heat liable toxins - 80 degrees for 10 mins
* resists action of gastric and intestinal juices
* any foods associated with anerobic conditions - cooked meats (canned), fermented foods
42
Symptoms of botulinum toxins?
* paralysis
* nausea
* double vision
* respiratory failure
* headache
* lack of fever
* great muscular weakness
* fatigue
* 60-100% mortality
43
duration of botulinum illness?
* 1-10 days
44
