VPH Flashcards
What is a zoonotic disease?
Diseases of humans in which the infectious agent is acquired from animals and for which animals are the reservoir of infection
What is an emerging infectious disease?
One that has appeared in a population for the first time or which may have existed previously but is rapidly increasing in incidence or geographic range (75% are zoonotic)
What are some reasons for emergence (and spread) or EADs?
- Ecological changes or disruption (eg. Climate change, vectors)
- BTV - Introduction of animals/people to new areas
- Hendra, SARS - Increasing global movement(both people and animals)
- Swine flu - Cultural changes and changes to agricultural practices
- Enhanced disease surveillance and detection (eg. High throughput DNA sequencing technologies)
What are some general impacts of emerging infectious diseases?
- Animal health and welfare
- Human health
- Economic impacts
- Social impacts
- Trade restrictions
- Environmental
- Political
What are some important features of modern abattoirs?
- Stunning prior to slaughter
- Abattoir design to minimise stress
- Protocols/ procedures to maximise animal welfare at all stages (transport, lairage, stunning, slaughter)
- Design, protocols/procedures to maintain food safety
- Design, protocols/procedures to maintain worker safety
What is the purpose of stunning an animal before slaughter?
To render animal unconscious and insensible to pain prior to slaughter
What is sticking?
Blood vessels carrying oxygenated blood to the brain are severed during slaughter
What is the difference between reversible and irreversible stunning?
Reversible- animal can recover sensibility. Therefore brain function needs to be stopped by another method (sticking). Period of insensibility needs to continue until animal is dead
Irreversible- animal will die if not slaughtered but sticking is still done
Describe head only stunning. Include how long it lasts, what animals it is used in etc.
Electrodes either side of head. Electrical waves induce an epileptiform seizure. Period of insensibility is about 45 seconds
Used in small livestock (sheep, goats, pigs, calves) and poultry
Acceptable for halal
What are the phases and signs of an effective stun?
Tonic phase: 10-20 secs. Animal collapses and becomes rigid. No rhythmic breathing, head is raised, forelegs extended and hind limbs flexed into the body.
Clonic phase: 10-15 secs. Gradual muscle relaxation, paddling/ involuntary kicking. Downward eyeball movement, urination/ defecation.
Recovery: resumption of normal rhythmic breathing, response to painful stimuli, visual awareness, attempts to stand.
Describe non penetrative captive bolt stunning?
Mushroom head captive bolt 4apidly accelerates and decelerates the brain. Causes massive stimulation and firing of neurones leading to insensibility.
May cause subdural haemorrhage
Needs sticking after
What are some signs of an effective stun using captive bolt?
- Animal drops and stays down
- Uncoordinated hindleg kicking
- No corneal reflex
- Cessation of rhythmic breathing
- No vocalisation
- No rotation of eyeball
- No coordinated attempts to rise
In which species in CO2 stunning most commonly used? Why?
Pigs! Involves 80-90% CO2. Pigs lose consciousness within 30 secs. It’s used because it lets pigs stay in groups
What is a controlled atmosphere chamber?
Stunning chamber used for poultry. CO2, argon and nitrogen
What is head to back electrical stunning? Is it reversible? What animals is it used in?
Causes epileptiform seizure and fibrillation of the heart. Loss of heart function, blood stasis, deceased O2 supply to brain.
Used in small livestock.
IRREVERSIBLE!
What is penetrative captive bolt stunning?
Bolt aimed towards the brain stem. Results in percussive wave within brain tissue. Used in cattle, goats and sheep.
IRREVERSIBLE!
What is the most effective method of bleeding?
Chest stick - rapid blood loss, shortest time to loss of function. (At throat in sheep and goats
What are some requirements of a lairage? (There’s quite a lot, just know a few)
Non slip floors Curved races High walls Minimal distractions Move animals in small groups Free access to water Room to lie down Antemortem vet inspection Access to feed if held a long time Easy to clean Protected from extreme weather
What are the two types of restraint systems used in abattoirs?
- Conveyer restrainers (use with captive bolt or electrical stunning. In large plants)
- Stun boxes/crush restrainers (cattle. For use with captive bolt stunning)
What four factors do you need to consider when thinking about what meat-eating consumers want?
Verification, safety, quality and healthiness
Also, safe process for workers and animal welfare
How does bruising or injury affect meat quality?
Higher pH causes quicker decomposition. Bloody meat pro,Oates growth of contaminating bacteria such as clostridium chauvei
What may cause blood splash in meat?
Pre-slaughter stress or excitement
Some electrical stunning conditions
Long stun to stick intervals
Higher temperatures
What is dark cutting beef? How is it avoided?
Meat that is drank in colour, dry and sticky. Higher ph and reduced shelf life. Arises from longer term stress pre-slaughter. Related to low glycogen levels in the muscle before slaughter*
Avoid by:providing adequate on-farm nutrition. Reduce physical and psychological stress (think of the nutrition bucket!)
*After death, glycogen is broken down. Produces lactic acid which lowers the pH. Low glycogen stores mean higher end pH
What is the ideal pH range for meat? What is the pH of DCB?
Ideal= 5.4-5.7 DCB= 6.0-7.0
What causes pale, soft exudative pork? How can it be avoided?
Severe, acute stress just before slaughter. Leads to accelerated rate of glycolysis just after slaughter ➡️ too much lactic acid ➡️ very low pH
Avoiding it: keep pigs cool in hot weather, chill meat quickly, genetic selection, reduce stress at abattoir, CO2 stunning
When does antemortem inspection occur? What does it involve?
12 hours prior to slaughter. Involves:
- Review documentation and ID stock
- Inspection of the stock
- Make disposition (fit or unfit for slaughter)
What are some common chronic sequelae resulting from food-borne illness? What are there associated pathogens?
▪️Guillain-Barre syndrome (campylobacter, salmonella, other)
▪️Haemolytic uraemia syndrome (E.coli STEC)
▪️Irritable bowel syndrome (campylobacter, salmonella)
▪️Reactive arthritis (campylobacter, salmonella, other)
Food-borne disease may arise from which main sources?
- Animals (zoonoses) that produced the food
- Contamination during processing
- Toxins or chemicals with animal or from environment
What are the common causes of gastrointestinal food-borne disease in Australia? (5 bacteria, 5 viruses, 2 Protozoa)
Which of these cause severe* disease?
- Pathogenic E.coli
- Campylobacter*
- Salmonella*
- Clostridium perfringens
- Bacillus cereus
- Norovirus*
- Sapovirus
- Adenovirus
- Astrovirus
- Rotavirus*
- Giardia lamblia*
- Cryptosporidium spp.*
What are some common causes of NON-gastrointestinal food-borne disease in Australia?
- Toxoplasma gondii*
- Scrombotoxin
- Ciguatera toxin*
- Listeria monocytogenes*
- Hepatitis A virus*
What results in more deaths annually, campylobacter or salmonella?
Salmonella. Campylobacter does cause more cases of disease though.
High risk foods for listeria include…?
Soft cheese, pate, cold meats, cooked diced chicken
What order of events takes place with an outbreak of food borne disease?
- Detection and notification
- Investigation
- Investigation of farms implicated in outbreak
Which group A diseases reuire immediate notification to the department of health?
- Typhoid and paratyphoid
- Botulism
- Cholera
- Haemolytic uraemia syndrome
- 2 or more cases of food/waterborne illnesses
Group B diseases require notification within how many days? What are some examples?
5 days
- Listeriosis
- Salmonellosis
- Shigellosis
- VTEC/STEC
- Campylobacteriosis
- Cryptosporidiosis
- Hepatitis A and E
What sort of study would you normally conduct to investigate a point source epidemic? How about cluster outbreak?
Cohort study (RR) Case study (OR)
What components comprise an outbreak investigation?
Epidemiological, environmental, laboratory investigations.
Trace back investigation, on-farm investigations
What are some common problems with outbreak investigations?
- Accuracy of lab typing methods
- Timeliness
- Sensitivity of detection methods
- Confounding
- Investigator experience
- Type of outbreak
- Setting of outbreak
- Traceability
What are some reasons as to why developing countries are more vulnerable to food borne disease?
Unsafe water Inappropriate/ unsafe use of agriculture chemicals Poor food processing/storage Poor regulatory standards Poorly developed healthcare systems Lots of chronically sick people
What are some common causes of food-borne disease globally?
Taenia solium
Salmonella typhi
Shigella
Vibrio cholerae
What are some diseases targeted by meat inspection procedures in Australia?
Bovine TB Actinobacillus lignieresii Actinomyces bovis Corynebacterium pseudotuberculosis Cysticercus bovis Liver fluke Onchocerciasis Taenia ovis
What is HACCP?
Hazard analysis critical control point
= science based system of identifying, evaluating and controlling hazards which are significant for food safety. PREVENTATIVE APPROACH
What are the seven principles of HACCP?
- Hazard analysis
- Identify critical control points
- Establish critical limits
- Monitor the critical control points
- Establish corrective action
- Record keeping
- Verification
What are some perceived benefits and barriers to the Hendra vaccine?
Benefits: protect horse/human health, required for participation, required for vets to treat
Barriers: cost, vaccination schedule, vet only, safety concerns
What are some side effects of the Hendra vaccine?
Swelling and soreness at site Fever Lethargy Loss of appetite Muscle stiffness Skin rashes Colic
What factors have contributed to a rise in chicken and pork consumption?
Higher feed conversion efficiency
Faster growth
Concerns with red meat consumption.
What is white spot disease?
Disease affecting prawns
According to ausvetplan, an emerging animal disease is…?
a. Exotic to Australia
b. A variant of an endemic disease
c. A serious infectious disease of unknown or uncertain cause
d. A severe outbreak of a known endemic disease
e. Of national significance with social or trade implications
What are the key steps to an emerging animal disease outbreak response?
- Defining problem
- Quarantine and movement controls
- Surveillance and tracing
- Disease elimination
- Proof of freedom
