Food-Borne Zoonosis Flashcards
What is the WHO definition of zoonosis?
Diseases and infections naturally transmitted between animals and humans
What is the definition of a ‘food-borne’ disease?
acute illnesses associated with the recent consumption of food
What is the definition of a foodborne infection?
where a disease is caused by an infection (e.g salmonella/ campylobacter)
What is the definition of foodborne intoxication?
Disease resulting from a toxin (usually bacterial e.g staphylococcus)
What are some examples of bacterial foodborne infections?
salmonelliosis, typhoid fever, cholera, campylobacter,
What are some examples of viral foodborne infections?
hepatitis A, norwalk infection, poliomyelitis virus
What are some examples of mycotic foodborne infections?
candida, sporothrix
What are some examples of parasitic foodborne infections?
protozoa, roundworms, tapeworms
What are the two species of salmonella?
- Salmonella bongori
- Salmonella enterica
How many subspecies is s.enterica split into?
2500
What salmonella species is the most common cause of human infection?
S.enteriditis
What are the symptoms of salmonella enteriditis?
Acute onset fever, diarrhoea, abdominal pain, nausea
What can prolonged salmonella symptoms lead to?
dehydration
What kills salmonella in the environment?
- Killed by temperatures attained in commercial pasteurisation
- they are **not ** destroyed by carcasses or offal kept in freezing temperatures
What are the two campylobacter species of public health importance?
- campylobacter jejuni
- campylobacter coli
What is the campylobacter reservoir?
Intestinal tract of wild/domesticated birds and mammals
What is the incubation period of campylobacter?
2-5 days
What are the symptoms of campylobacter?
watery or bloody diarrhoea, abdominal pain, fever, headache and nausea
What is the public health significance of human campylobacteriosis?
- causes painful diarrhoea
- invasive in over 65’s
- most common cause of bacterial gastroenteritis
- can also cause neuropathological conditions
What is the shape of the listeria pathogen?
Gram positive rod-shaped pathogen
What species of listeria causes almost all human cases of listeriosis?
Listeria monocytogenes
What is the reservoir of listeria monocytogenes?
Plant matter and soil
What is listeria monocytogenes associated with?
cooked meat, pate, soft cheese, smoked fish,
What is the incubation period of listeria monocytogenes?
mild-flu to diarrhoea to abortion/ life threatening diseases
What is the fatality rate of listeria in the EU?
12.7%
What are most human E.Coli cases linked to?
poorly cooked beef, cross-contamination from raw meats,
What is one of the benefits of E.Coli being in the normal gut flora?
Vitamin K synthesis
What are the 5 groups that E.Coli strains fall into?
- Enteropathogenic E. coli (EPEC)
- Enterotoxigenic E. coli (ETEC)
- Enteroinvasive E. coli (EIEC)
- Enterohemorrhagic E. coli (EHEC)
- Enteroaggregative E.coli (EAEC)
Summarise Enteroinvasive E.coli
- characterised by watery diarrhoea in most patients
- fever, nausea and abdominal cramps
- bloody diarrhoea in less than 10% of patients
- illness is usually self-limiting
- high dose is required to cause infection
Summarise enterohaemorragic e.coli
- caused by escheria coli serotype 0157:H7
- causes haemorrhagic colitis
- characterised by bloody diarrhoea, abdominal pain that can then induce vomiting
- has an incubation period of 3-4 days
- death occurs in patients that develop hemolytic uremic syndrome
What does yersinia enterolitica cause?
Food borne yersiniosis
What are the four species of shigella that cause human dysentry?
flexneri, boydii, sonnei,
dysentriae
How is shigella transmitted?
either foodborne or person to person
What can food borne intoxications be classified into?
- bacterial
- fungal
- chemical
- plant
- poisonous
What are some bacterial food pathogens that cause intoxication
- staphylococcus aureus
- bacillus cereus
- clostridium
- perfringens
Summarise staph aureus
- faculative anerobe, produces spores
- intoxication is caused by eating food contaminated with staphylococcal enterotoxins
- the organism produces five different enterotoxins
Summarise staph enterotoxins
- they are all heat stable
- they are insensitive to pH changes
- resistant to proteolysis enzymes
- not affected by irradication
- all five have a similiar potency
Why does the majority of staph.aureus poisioning occur when microbial flora is reduced?
Staphylococcus aureus is a poor competitor and
therefore grows poorly or not at all when growing
together with other microorganisms
What are some of the symptoms of staph aureus?
Incubation period is 1-6 hrs after consumption of food
contaminated with at least 1.0 µg of enterotoxin.
* Clinical signs include salvation, nausea, vomiting,
abdominal cramps, sometimes diarrhoea with
prostration.
* Duration of illness is 24-72 hrs.
* Dose of 1.0 µg or more is needed to cause disease
Summarise bacillus
- gram positive, spore forming rod
- Produces 3 different toxins (emetic and two diarrhoeal)
What are the two diarrhoeal endotoxins?
a) hemolysin BL enterotoxin
b) non-hemolytic enterotoxin
What is the main source of bacillus?
it is frequently isolated from meat, eggs and dairy products
* Cereal dishes e.g. rice, pulses, spice, mashed potatoes, herbs,
vegetables, minced meat, cream and milk pudding.
* Vegetative cells killed by cooking, spores are not
* If cooked rice/pulses are not chilled, spores can germinate,
bacteria grow and toxins produced
What are the symptoms of emetic syndrome?
The syndrome is characterised by nausea, vomiting, abdominal
cramps and sometimes diarrhoea that occur 1-6 hrs after
consumption of contaminated food. The syndrome is associated
with ingestion of rice and pasta based foods.
What are the symptoms of diarrhoeal syndrome?
In the diarrhoea syndrome, patients experience profuse diarrhoea
(watery stool), abdominal cramps and tenesmus (rarely vomiting)
beginning 8 to 16 hours after ingestion of contaminated food.
Fever is absent and symptoms resolve within approximately 12
hours.
What are the three species of clostridum?
- C.perfringens
- C. botulinium
- C.difficile
Where is the clostridium perfringens enterotoxin produced?
GIT
