Final Exam Review Flashcards
Understand why new diseases (particularly zoonotic and vector-borne diseases) are emerging so frequently in recent times
EI-ICE
- Ecological changes or disruption (particularly climate change)
- Introduction of animals/ people to new areas
- Increasing global movement (people and animals)
- Cultural changes and changes to agricultural practices
- Enhanced disease surveillance and detection e.g. molecular methods
What would you do to control and prevent foodborne disease?
What is veterinary public health?
The sum of all contributions to the physical, mental and social well-being of humans through an understanding and application of veterinary science
What is “one health?”
Concept incorporating interdisciplinary collaborations and communications in all aspects of healthcare for humans, animals, and the environment. Recognizing that human health, animal health, and ecosystem health are inextricably linked.
One health seeks to promote, improve, and defend the health and well-being of all species by enhancing cooperation and collaboration between physicians, veterinarians, and other scientific health and environmental professionals.
Zoonotic diseases vs. Foodborne diseases with veterinary involvement
Zoonotic diseases- Diseases of humans in which the infectious agent is acquired from animals and for which animals are the reservoir of infection.
Food borne diseases can be from zoonoses infected that animal, infectious diseases due to contamination, diseases due to the presence of chemicals or toxins (natural or contamination)
Describe the broad range of impacts that these emerging infectious diseases can have on animals, people and the environment
Describe the different roles that veterinarians can play in investigating, controlling and preventing emerging infectious diseases
What is an emerging disease?
One one that has appeared in a population for the first time or that may have existed previously but is rapidly increasing in incidence or geographic range. (About 1 new disease per year for the past decade or more)
Explain and provide an example of the ecological changes or disruption aspect of EIDs? Examples?
Climate change–> precip, extreme weather (droughts and floods), and seasonal shifts which impact disease agents, vectors, and hosts and their interactions.
* Disease agents- altered pathogen survival, Vectors- change to habitat, hosts- stress, malnutrition
* Examples: Hendra virus- floods and extreme weather in QLD caused flying foxes to move further south to northern NSW where the first cases of Hendra Virus emerged due to naive population of flying foxes therefore when infected, increased viral shedding, increased chance of spillover
Why does the introduction of animals/ people to new areas result in increased EIDs?
* Displacement for political, social, or economic factors brings domestic animals and people into contact with wildlife and their infectious agents to which they had not previously been exposed– can occur periodically, Hendra Virus or sustained transmission and the disease becomes established in that host population e.g. HIV
Why is increasing global movement of people and animals a factor in EIDs?
* Movement of people and animals is not new but the scale and speed of this movement has increased dramatically in recent history
* visitors or new populations may have no immunity to introduced pathogens e.g. malaria
* genetic determinants of resistance can be transferred to other local pathogens
* new vectors may facilitate transmission of local or introduced pathogens
How do cultural changes and changes to agricultural practices add to EIDs?
* Rapidly expanding global population and increased demand for animal protein in developing countries with rising incomes is driving increased production of meat and other animal food products WHICH contributes to intensification of animal production systems: spread of infectious diseases, waste management problems & use of in feed antibiotics which adds to the emergence and spread of antibiotic resistance via the food chain, contaminated environment, resistance genes spreading between bacteria.
How does enhanced disease surveillance and detection add to EIDs?
Improve methods of detecting pathogens- especially molecular methods such as PCR and DNA sequencing which contributes to the identification of new disease agents.
What is the role of veterinarians in EIDs?
Emerging zoonoses- clinical veterinarians– protect themselves (PPE, hygiene, infection control), protein their staffa nd clients, disease detection and reporting, assist in outbreak investigation and control.
* also laboratory diagnosis and detection of disease agents, research e.g. vaccine developement, pathogenesis, epidemiology, policy development
Impacts of EIDs. Specific example?
* Animal health and welface- animal illness, death, culling
* Human health- illness, death, psychological distress
* Economic impacts- direct- loss of animals, loss of production or indirect- associated industries, tourism
* Social impacts- loss of livelihoods, movement restrictions
* Trade restrictions- animals and animal products
* Environmental- carcass disposal, use of chemicals, PPE
* Political
** Specific example: FMD- 2001 in the UK. 2000 cases of disease. 10 million livestock culled. Control efforts focused on movement restrictions (animals and humans), culling and burning all animals near an infected farm (3 km). No vaccination used. Not a zoonotic disease but still psychological human impact.
To describe the principles, methods and equipment involved in humane slaughter, including stunning and ‘sticking’
Stunning- water bath for chickens with electrical stunning, scissor tongs for pigs and sheep, non penetrative captive bold (especially for cattle)
Sticking
To know the signs that indicate a stun has been effective (electrical stun)
* Tonic: animal collapses and becomes rigid, no rhythmic breathing, head is raised, forelegs extended and hind legs flexed into the body
* Clonic: gradual relaxation of muscles, paddling or involuntary kicking (can be severe at times), downward movement of eyeballs, urination and/or defecation
* Recovery: resumption of rhythmic breathing, response to painful stimuli, becomes visually aware, attempts to stand
To describe the principles surrounding the structure and design of a modern abattoir
To know the processes that take place in a modern abattoir
* Stunning prior to slaughter
* Abattoir design to minimize animal stress, maximize animal welfare
* Animal welfare in mind for transport, lairage (where they are rested on the way to slaughter), stunning, slaughter
* Design and protocols for food and worker safety
To understand the relationships between animal welfare, food quality and food safety
* calm cattle= lack of adrenaline which makes tough meat, dark cutters, bruising (cannot be used for food)– minimizing stress and physical damage
Reversible stunning methods vs. irreversible– examples?
* Reversible- animal is able to recover sensibility. The brain function must be stopped by other means- severing blood vessels carrying blood to the brain. The period of insensibility needs to continue until death supervenes.
* reversible examples: CO2 stunning, non penetrative captive bolt, head only electrical stunning (electrodes must span the brain- used for small livestock)
* Irreversible stunning- animal will die if not slaughtered but sticking is still performed so that the animals are bled out before further processing to guard against unexpected return to sensibility following stunning
* Irreversible examples: head-to-back electrical stunning (epileptiform seizure and secondly fibrillation of the heart- loss of heart functionality and therefore blood stasis and reduced oxygen supply to the brain– small livestock), penetrative captive bold (passes between the cerebral hemispheres and hits the region above the hypocampus = massive disruption of all areas of the brain- often used in cattle)
Signs of an effective stun using captive bolt (penetrative or non-penetrative)
* animal drops immediately and stays down
* uncoordinated hind leg movements- kicking
* no corneal (blink) reflexes
* cessation of rhythmic breathing
* no vocalization
* no rotation of the eye ball
* no coordinated attempts to rise
What is CO2 stunning?
Currently used for pigs– 80-90% CO2- pigs lose consciousness within 30 seconds- can be some struggling or excitement within 30 seconds
** with poultry mixture of CO2, nitrogen, and argon
What is the most effective method of bleeding?
Chest stick- faster bleed out
** must sever the blood vessels close to the heart in cattle and pigs
What would happen if you severed the carotid arteries 5 seconds after stunning a cow?
* the stun would render the cow insensible for 45 seconds but severing the carotid arteries only would take 90 seconds for the cow to become insensible– therefore there would be a time where the animal was sensible and feeling pain
Good abattoir design
* Abattoir design is informed by animal behaviour
* Good management and staff training is essential
* Good animal welfare and good meat quality are linked
* Good restraint systems are needed for effective stunning
* Kicking on the line after stunning does not indicate a return to sensibility
* Attention to small details is vital
* animal welfare auditing is important
* curved- can’t see what is up ahead
* move in small groups
* will head towards light
* non-slip floors
* 75% full pens
How does flow work in an abattoir?
Lairage–>kill floor–> skinning & eviceration–> offal room OR hide room OR chiller–> boning room–> freezer
What are the exits in an abattoir?
Offal, hides and skins, whole carcase from the chiller, fresh cuts from the boning room, and frozen cuts from the freezer
What are the percent breakdown of retail value of products?
5% hides, 80% meat, 9 % rendering/pharmaceutical product, 6% offal
What are good design principles of lairage?
* Non slip floors, curved races, high walls, minimal distractions, move animals in small groups, free access to water, room to lie down, keep animals of similar types together, ante-mortem inspection of all animals by veterinarian (AQIS), access to feed if held for prolonged period, facilities need to be easy to clean, animals should be protected from extreme weather conditions
What are good design principles of restraint systems? What are two types?
* important for achieving accurate placement of stunning devises and thus for achieving effetive stun
* removes the need to immobilize animals using other (inappropriate) methods
- conveyer restrainers- pigs, sheep, cattle- for use with captive bolt or electrical stunning, large plants
- stun boxes/ crush restrainers- cattle, captive bolt stunning
Key design principles of conveyer restrainers– when is this preferred vs. stun boxes?
Over 100 an hour this is better than a stun box
What is the problem with dark cutting beef? What is the ideal pH of meat?
* Less glycogen at slaughter= less lactic acid= higher pH
ideal pH is 5.4 to 5.7
How do you avoid dark cutting beef?
* Adequate nutrition on farm (feedlot cattle have higher levels of muscle glycogen, grazing cattle should be put at pasture at least 2-3 weeks before slaughter or should receive supplementary feed)
* Avoid physical and psychological stress (farm to slaughter)- good facilities, handling, procedures
What are the key abattoir processes to preserve food safety? Which occur on the clean side and which on the dirty side?
- ante-mortem inspection
- post-mortem inspection
- chilling
Apply HACCP principles to relevant hazard
Contamination of meat with enteric bacteria (E. coli, Salmonella, Capylobacter)
- Hazard analysis– slaughter process, dressing and processing of carcass, and inappropriate handling of the product
- CCPs and 3. Establish critical limits- CCP1 primary meat inspection (no visible signs of fecal material on the carcasses- zero tolerance- absence or presence), CCP 2- chilling (reduce surface temperature of carcasses to 4C or below within 24 hours (deeep muscle temp 6-7C within 36 hours for beef, 16 hours for pigs, 30 hours for sheep)
- Monitor the CCPs– Meat safety inspection & check the checker; monitor surface and internal temperatures of carcasses each day
- Establish corrective action– What would happen if fecal contamination? Contaminated meat is trimmed and condemned, further training of staff, review inspection procedures, review infrastructure. What would happen if meat did not reach required temperature in time? Removed from production chain, review chilling procedures, review equipment/ infrastructure
- Record keeping- written and maintained HACCP plan, all records generated during monitoring of each CCP, records of any deviations from CL and the corrective actions taken
- Verification- Sampling and analysis (ESAM program- E.coli and Salmonella program- set number of carcasses randomly selected for swabbing e.g. 1 test per 1500 carcasses, swabs sent to lab for testing and bacterial enumeration)
List 3 Group A & 3 Group B diseases
What are point source outbreaks?
What are cluster outbreaks?
Demonstrate an understanding of the epi of influenza
* Type A influenza infect birds and mammals (humans too)– associated with all pandemics (seasonal epidemics)
* generally from birds or pigs- amplifier host which spreads widely due to naive popultion to new virus
* Generally severe disease in very young, old, and immunocompromised but occasionally like 1918 it can primarily cause disease in young adult population due to strong immune systems and cytokine storms (2009 swine flu was the same)
** concern is always a reassortment or mutation that can transmit person to person that is highly pathogenic
Control measures: vaccination (mainly against HA, updated every year or so), disease containment (isolation, quarantine, social distancing, physical barriers, hand and personal hygiene, use of PPE by healthcare workers), antivirals
** But cannot predict the strains, 4-6 month delay before vaccine strains can be characterized and grown up in bulk, leaves the population vulnerable in the early stages of a pandemic
** WHO decides which strains- meet twice annually
Describe the pathogenesis of Ebola
* entry through mucous membranes and broken skin, infectious dose 1-10 particles, saliva, tears, breast milk, faeces, semen, urine
* propagation generally involves intimate contact
* non specific flu like symptoms of fever, myalgia, malaise–> GI bleeding, rash, haematological irregularities such as lymphopenia and neutrophilia, cytokines contribute to inflammatory response, damage to the liver combined with massive viraemia = DIC
* CFR- 50-90%
Epidemiology of ebola
* Bats as reservoir host for ebola viruses (Ebola, Sudan, Tai Forest, Bundibugyo, Reston virus-non human)– endemic cycle within bat populations
* epidemic cycle. Bats–> primates–> other mammals–> humans
** there are populaton rsk areas– predicted distribution due to bat habitat, elevation, etc.
How can Ebola be handled safely in a laboratory setting?
Classified as a Level 4 agent on the basis of a high CFR and absence of therapeutics or vaccines
* Do not mouth pipette, restricton of needles and syringes, avoid spills and production of aerosols by being careful, use PPE, wash hands, decontaminate, do not eat drink store food or smoke in the lab
** PC4- handling of highly dangerous pathogens to personnel and environment that might cause lethal disease with no treatment options
** Class II cabinet- with HEPA filter for air (PC 2-4), biologiacl waste- holding tank with chemical treatment then sterilization (autoclave)
describe how influenza activity is monitored and describe the control measures that can be used for seasonal and pandemic influenza
WHO monitors via the Global Influenza Surveillance and Response System
*ID and monitor influenza viruses circualting in human population, monitor antigenic drift, monitor emergence of seasonal virus variants resistant to antiviral drugs, make annual recommendations on composition of influenza vaccines, early detection of unusual influenza viruses in human population (= pandemic potential)
What samples are taken to detect influenza?
What is detected and what tests are used to detect influenza?
What are the basic components of a PC4 lab?
