EPI 1.0 Flashcards
define an emerging infectious disease
One that has appeared in a population for the first time, or that may have existed previously but is rapidly increasing in incidence or geographical range
List the 5 main reasons diseases are emerging and spreading
1) Ecological changes or disruption (climate change)
2) Introduction of animals/people to new areas
3) Increasing global movement (people and animals)
4) Cultural changes and changes to agriculture practices
5) Enhanced diseases surveillance and detection
What about ecological changes or disruption leads to emergence of disease and what are the 3 important factors
Changes in precipatation, extreme weather events (droughts and floods) and seasonal shifts can directly impact disease agents, vectors and hosts and their interactions
1) Disease agents -> altered pathogen survival, replication or distribution
2) Vectors -> changes to habitat, vector distribution, altered contact with hosts
3) Hosts: stress, debilitation, malnutrition, or post-disaster injury as populations response to extreme weather events Disease agents with external (eg, nonhost) portions to their life cycles are more likely to be influenced by ecological change (i.e. parasites and food-, water-, and vector-borne diseases)
Give an example of how an emerging disease occurred due to ecological change or disruption
Emergence of bluetongue virus in Europe - Transmission of BTV is affected by temperature due to intermediate host (Culicoides)
1) Extrinsic incubation is faster
2) Vector number increase
3) Vector distribution expands
Introduction of animals/people to new areas what is it driven by and how does it lead to emerging diseases
- Driven by many factors
○ Climate change and environmental factors
○ Agriculture/urbanisatin on nautral ecosystems
○ Displacement of people due to political, social or economic - Bring domestic animals and people into contact with wildlife and their infectious agents
- Infections can then be transmitted from wildlife hosts to domestic animals -> spillover events
Give 2 examples of how introduction of animals/people to new areas lead to the emergence of diseas
1) Hendra virus: fruit bats -> horses -> humans (Australia)
2) Nipah virus: fruit bats -> (pigs) -> humans (Malaysia and Bangladesh)
What makes bats a good vector for disease transmission
1) Bats have some unique immunological features
- can have more persistent viral infections
- can be more susceptible to reinfection
2) Bats have behavior characteristics that favor virus transmission
- live in large populations
- migrate large distances
- live in close proximity to human populations
increasing global movement what are the 2 main ways it leads to emergence of diseases
1) Movement of people and animals is not new just the scale and speed of movement has increased dramatically in recent history
○ Sea and land travel
○ Air travel -> easier to control due to restriction on products that can take with you
2) The incubation period of many infectious diseases in now longer then the time it takes to circumnavigate the globe
○ Can no longer control More than 1 billion international travels per year
Give an example of a disease that emerged from increasing global movement
Emergence and spread of H1N1 in 2009 - H1N1 pandemic in 2009 - 2010
- Emerged in Veracruz , Mexico
- Rapid global spread, despite control efforts (closure of public facilities, travel restrictions, travel warnings)
- Very highly studies pandemic
- Mortalities estimate to be 300,000 to 500,000 (normal seasonal influenza)
Cultural changes and changes to agriculture practices how does this mainly lead to emergence of disease
A 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
- Increase demand for animal protein contributes to
○ Intensification of animal production systems
§ Spread of infectious disease
§ Waste management problems
○ Use of in-feed problems
§ Emergence and spread of antibiotic resistance
□ Via the food chain
□ Via a contaminated environment
□ Resistance genes can spread to other bacteria
Enhanced disease surveillance and detection how does this result in emergence of new disease and the 2 ways these are identified
Enhanced surveillance systems and improved methods of detecting pathogens contribute to the identification of new disease agents
1) PCR requires some knowledge of the infectious agents
§ Some sequence information is required for primer design
2) Newer ‘high throughout’ DNA sequencing technologies can detect and identify infectious agents without targeted PCR amplification
§ Very well suited to the detection of novel pathogens
§ Can reveal whole genome sequence information
What are the 7 main roles of clinical veterinarians in emerging diseases
- Protect themselves - PPE, hygiene, infection control
- Protect their staff - supervise and advise on PPE, hygiene, infection control
- Protect clients - advise on PPE, hygiene, infection control
- Disease detection - recognise and report diseases
- Assist with disease surveillance in animals
- Assist in outbreak investigation and control
- Work with human health professional and other scientists in controlling any animal reservoirs of human infections
List 5 roles of government, university veterinarians
- Laboratory diagnosis and detection of disease agents
- Co-ordinate animal surveillance and idsease ocntrol measures
- Liaise with media, politicians, industry, other stakeholders
- Research (vaccine development, pathogenesis, epidemiology)
- Policy development
List some difference between the veterinary and medical professions
1) Herd animals are usually managed as a group with few rights for the individual animal; not the case in human medicine
2) For vets quality of life of their patient is more important than life itself; for doctors life is paramount
3) Economic issues are a very important factor in veterinary decisions (life and death at times); costs only modify management for doctors
4) Consent of owner not always critical for vets as consent can often be overruled by legislation; consent of patient or guardian is very important for doctors (very difficult to overrule)
5) Animals can be killed because they are ill, suspected of being ill, or close to another ill animal; not so for humans
6) Vets have more power to enforce their decisions; doctors have to convince patients and populations to do what is best
List 7 main impacts of emerging infectious disease and examples within
1 ) Animal health and welfare - Animal illness/deaths from disease - Culling
2) Human Health - Human illness/death from disease - Psychological distress
3) Economic impacts - Direct (loss of animals, loss of production) - Indirect (associated industries, tourism)
4) Social impacts - Loss of livelihoods, movement restrictions
5) Trade restriction - Animals and animal products
6) Environmental - Carcass disposal, use of chemicals, PPE (single use - more plastic, disinfecting with chemicals)
7) Political
What are the 2 main areas of economic impacts from FMD 2001 outbreak and how affected
AGRICULTURE & FOOD INDUSTRY
- Ban on British exports of livestock, meat and animal products
- Culling for disease control measures or welfare reasons
- Production losses, disease eradication costs, trade disruption
- Agricultural producers (animals), Agricultural producers (feed), Food industry (auction markets, abattoirs, processors, transporters)
TOURISM - Tourists changed their plans, delayed trips, cancelled trips, switched destinations within UK
- Accommodation, catering, attraction and transport TOTAL - 8.6 billion pound
2001 FMD outbreak what was the main environmental and human health impacts
Environmental -> disposal of dead carcasses
Human health ->
- Not a zoonotic disease
- Significant psychosocial effects
○ Vets getting death threats ○ seeing the animals burning on pyres -
Not just farming communities
○ Distress
○ Feeling of bereavement ○ Fear of new disaster
○ Loss of trust in authority and systems of control
What are the main animal health and welfare impacts for FMD outbreak in 2001
1) Animal welfare impacts related primarily to control measures
- Mass culling of healthy/uninfected animals for disease control
- Mass culling of healthy/uninfected animals due to welfare concerns arising from movement restrictions
2) Animals couldn’t be transported to abattoirs, mass culling in the field
- Reduced options for killing methods
- Lack of suitable equipment
- Lack of suitably trained people
- Lack of suitable facilities (including restraint)
- Fatigue (staff and equipment)
What are the political impacts of the FMD 2001 oubreak
Loss of public confidence in government Conduct and policies of MAFF heavily criticized
- Underprepared - Unwillingness to use vaccination
- Poor coordination and mismanagement (early days of outbreak)
- Use of the army - Confrontation attitude towards farmers and farming communities
- Failure to recognize the impact of movement restrictions
- Failure to pay adequate and timely compensation
- No public inquiry (3 policy inquiries) ○ Vaccination to be considered in any future outbreaks
what are the main differences with animals used as food in hunter/gather societies to agriculture societies
Hunter/gather ○ Different hunting/endurance hunting - cruel way § Persistence/endurance hunting § Spears § Bow and arrows § Throwing sticks, boomerang Agriculture societies ○ Domesticated animals ○ Slaughter +/- stunning ○ Consideration for animal welfare ○ Modern abattoirs
what are the main features of a modern abattoir
- Stunning prior to slaughter
- Abattoir design to minimise animals stress, maximise animal welfare
- Protocols/procedures in place to maximise animal welfare at all stages
○ Transport
○ Lairage - holding yards before go into the abattoir
○ Stunning
○ Slaughter - Design and protocols/procedures to maintain food safety/worker safety
What are the 2 steps involved in the humane slaughter of livestock in an abattoir and what is involved with each
1) Stunning - is performed to render the animal unconscious and insensible to pain priot to slaughter
- Slaughter can then be carries out painlessly (and safety for abattoir workers) - MUST BE DONE IN AUSTRALIA prior to slaughter
2) Slaughter occurs after stunning
- Blood vessels carrying oxygenated blood to the brain are severed (“sticking”)
- The result is death from lack of oxygen to the brain (cerebral anoxia)
What are the 2 different stunning methods, define them, what is important and which is mainly used in AUS
1) Reversible stunning methods - animals is able to recover sensibility
- The brain function of the animal must be stopped by another means (by severing blood vessels carrying blood to the brain
- The period of insensibility needs to continue until death supervenes
- Halal requires reversible stunning - MAIN USED IN AUSTRALIA DUE TO EXPORT
2) Irreversible stunning methods -
animal will die if not slaughtered ‘sticking’ is still performed so that the animals ‘bled out’ before further processing and to guard against any unexpected return to sensibility following stunning
What are the 3 reversible stunning methods and the 2 irreversible stunning methods
Reversible 1) head only electrical stunning 2) non penetrative captive bolt 3) CO2 stunning Irreversible 1) head to back electrical stunning 2) penetrative captive bolt stunning
Head only electrical stunning how achieved, how long insensible, what animals used in, what needs to occur
- Electrodes placed either side of the head result in passage of an electrical wave from one side of the brain to the other, introducing an epileptiform seizures.
○ The period of insensibility is approx. 45 seconds -
Generally used in small livestock (sheep, goats, pigs, calves) and poultry, rarely used in adult cattle - “sticking” must occur quickly after stunning to avoid return to sensibility (“stun to stick” interval)
Non penetrative captive bolt how works, what assocaited with, which animals commonly used for, what must occur afterwards
- A mushroom head captive rapidly accelerates and decelerates the brain in the cranial cavity with the effect of causing massive stimulation and firing of neurons and thus insensibility
- Often associated with this is general sub-dural haemorrhage
- Commonly used in adult cattle, can also be used for sheep, goat and pigs
- “sticking” must occur quickly after stunning to avoid return to sensibility (“stun to stick” interval)
List 7 signs of an effective stun using a captive bolt
1) The animal drops immediately and stays down
2) Uncoordinated hindleg movements - kicking
3) No corneal (blink) reflexes
4) Cessation of rhythmic breathing
5) No vocalisation
6) No rotation of the eye ball
7) No coordinated attempts to rise
CO2 stunning what animal mainly used in, how occurs, signs, what needs to occur afterwards
- Currently used for pigs
- Groups of pigs enter a chamber that is then filled with 80% to 90% CO2 in air (minimum 60% CO2)
○ Pigs lose consciousness within 30 seconds - Can be some struggling or excitement before loss of consciousness
- Immediate slaughter then needed to ensure the animal does not recover
- A variation of CO2, stunning is the controlled atmosphere chamber used for poultry (mixture of CO2, nitrogen, argon)
Head to back electrical stunning what result in and what animals used for
- This stun will result firstly in an epileptiform seizure and secondly fibrillation of the heart
- This causes loss of heart functionality, general blood stasis and reduced oxygen supply to the brain
- Generally used in small livestock (sheep and pigs), can be used in cattle
Penetrative captive bolt stunning where aim, what result in, animals used for a signs of effective use
- General rule: the bolt should be aimed towards the brain stem
- The captive bolt also results in percussive wave within the brain tissue increasing the disruption to normal nervous impulses
- Used in cattle, goats and sheep
- The signs of an effective stun are the same as those described for stunning with a non-penetrative captive bolt
Slaughter method, when does slaughter need to occur and why
- Animals should be slaughtered as quickly as possible after stunning, especially if a reversible stun has been applied
- This will ensure that animals do not regain consciousness before they are rendered permanently insensible due to cerebral anoxia following ‘sticking’
what is important to cut for slaughter
- Important to cut carotid and vertebral artery as supply to brain not the jugular vein as that is draining
What are the 2 main ways to “stick” an animal and which species
1) Chest stick - all
- Most effective method of bleeding -> thoracic stick at the level of the heart
○ Rapid initial blood loss and the shortest time to loss of brain function
2) Sheep and goats sticking can be performed by cutting the blood vessels at the throat
○ Don’t have well developed vertebral artery so don’t need to worry
In sheep what are the periods of insenibility for head-only electrical stun and chest stick and therefore max stun-to-stick interval
- Head-only electrical stun -> 45 seconds of insensibility
- MAXIMUM TIME BETWEEN -> 35 seconds - Sever carotid arteries - insensibility after 10 seconds
In cattle what are the periods of insenibility for head-only electrical stun and chest stick and conclusion from this
- Head-only electrical Stun - insensibility induced for 45 seconds
- Sever carotid arteries - insensibility induced after 90 seconds
- Would get a period of recovered sensibility -> POOR ANIMAL WELFARE
○ Need to do a chest stick to bleed out quickly
What is important about the chiller and what are the 4 main outputs of the abattoir
Chiller - Get everything within as soon as possible - To avoid microbiological contamination Outputs 1. Offal - edible and inedible 2. Hides and skins 3. Whole carcase sometimes 4. Fresh or frozen cuts
Lairage of the abattoir what are some important features for animal welfare
- Non slip floor
- Protected from the environment - sprinkles to keep cool in summer
- Curved races - naturally flow so don’t need to use electrode prods
- Minimal distractions
- Move animals in small groups
- Free access to water
- Room to lie down
- Keep animals of similar types and sizes together
- Ante-mortem inspection of all animals by a veterinarian (AQIS)
- Access to feed if held for a prolonged period
- Facilities need to be easy to clean
Restrain system in abattoir why is it important and the 2 main types, animal used for and what type of stunning used within
- Important for achieving accurate placement of stunning devise and thus for achieving an effective stun
1. Conveyer restrainers - Pigs, sheep, cattle
- For use with captive bolt or electrical stunning
- Large plants as expensive so small plants not cost-effective
2. Stun boxes/crush restrainers - Cattle
- For use with captive bolt stunning
What are some important features of restraint systems in abattoirs
- Narrow enough to prevent the animal from turning around
- Non-slip flooring
- possible solid false floor
- Appropriate lighting
- A head restrain may be used
○ Head restraint more important for non-penetrating captive bolt
○ Can use active or passive head restraint
