AVT session 2: Depopulation Strategies

Harm Kiezebrink
Research Fellow
Faculty of Veterinary Science Queensland University

Depopulation
 Rapid response management
 Culling
 Storage
 Transportation
 Composting
 Disposal
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© 2014 Applied Veterinary
Technologies Europe AB

Incident Command System Structure
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Incident Command System
 Clear management structure
 Veterinary officer, responsible for veterinary tasks, including
diagnose & sampling, animal welfare, reporting & clearance
management
 Non- veterinary field response manager, responsible for all non-
veterinary tasks, including culling, cleaning & disinfection & logistics
 Health & Safety officer supervising the human health during the
operation, including Occupational Health & Safety, gate management
 Administration & Finance officer supervising the financial
management, registration and communication processes
 Clear - enforceable - instructions instead of on-the-job training
 Each farm needs its own outbreak response plan
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Culling
Official definitions
 According to the OIE
 Carrying out under the vet authority, the
killing of animals infected and suspected
to be infected
 According to the FAO
 Designation of clean & infected zones
 Intensive disease surveillance within the
infected zone
 Quarantine of livestock movement
 Immediate slaughter and disposal of all
susceptible animals (depopulation)
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Culling
- Animal Welfare -
Animal suffering increases contamination risks
 Birds sweat extremely when they are killed
under stressed conditions
 Sweating causes the skin and feathers to be
wet, creating the perfect environment for
viruses containment
 Viruses hidden under feathers
Animal cruelty upsets people
 International protests
 Negative impact on consumption of poultry
products
6

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Summarizing
Strategy
What needs to be achieved
 Depopulate within 24-48 hours
 Use the most appropriate culling method:
 Killing humanly, according to the International standards
 Limited number of operators and easy to operate
 Limited exposure between responders and animals
 Use the technique that fits the outbreak situation
 Create an outbreak response plan for each farm location in
advance

Poultry Killing Methods
- Recommended by OIE -
4 generic categories:
 Physical
 Chemical
 Electrical
 Gaseous agents
 CO2 gas stunning
 Anoxia method (high expansion foam
filled with 100% Nitrogen)
Not recommended by the OIE:
 Low expansion fire fighting foam
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Physical stunning
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Electrical stunning
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CO2 gas stunning
Large-scale 1.100 liter containers

CO2 gas stunning
Alternative container systems
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CO2 gas stunning
Stable gassing
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Wet foam stunning
Fire fighting foam
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High expansion Nitrogen foam
The Anoxia method
 High expansion foam
bubbles, created under
low pressure condition
 kills by Anoxia – total
absence of Oxygen under
atmospheric
circumstances
 nitrogen and the
water/soap solution are
mixed in a foam nozzle
 Suitable for all sorts of
mammals and types of
housing
Picture 15.4
Picture 15.2 Picture 15.3
Picture 15.5
Picture 15.6
Picture 15.1
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 Carcasses and dead birds
 Feed stock
 Eggs and egg trays
 Litter and beddings
 Manure
 Organic waste products
 Organic building materials impossible to
decontaminate
 Disposables used during the response
operation
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Contaminated materials
- Organic materials & disposables -

Managing
contaminated materials
All contaminated materials must be
• Collected and conserved to prevent contamination
• Stored until further processed; transported to disposal location
• Safely disposed
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Collection & conservation
 Although the virus reproduction stops after the birds are culled,
they maintain a serious threat:
 Spray a soapy water over all materials and wait 24 hours before
the next disposal phase can start
 Viruses survive in organic materials, contaminated water, dust on the
feathers, cages, troughs, and manure belts
 Soap helps to break down the virus load on the infected materials
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Temporary storage
Temporary storage of contaminated
materials impose risks
 When the farm is located within a
densely populated area
 When the distance between farm and
disposal area becomes critical for
timely response
 When there are large volumes of
contaminated materials on the farm
19

20
Temporary
cold store on the farm
 Minimizing risks of virus reintroduction
 Package infected materials in 1 M3
disposable containers on pallets
 Freeze /store the materials safely on side
until safe disposal can be guaranteed
 Safe handling & transporting frozen plastic
bags
 Frozen contaminated plastic bags are
hard to rip open
 Materials on pallets are simple and easy
to handling logistically

Considerations to on site storage
- use disposable containers -
Contaminated materials need to be prepared for
safe transportation: use disposable containers for
this purpose
 Use heavy duty plastic bags with a maximum
capacity of 1 m3
 Place the plastic bags in a disposable container and
place the container on a disposable pallet
 Fill the container with contaminated materials
 Ziploc the plastic bag after it is full
 Remove the disposable container
 Disinfect the enclosed plastic bag and the
disposable pallet
 Store the pallet safely until further handling
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Incineration
Picture 18.1
 There are three broad categories of
incineration techniques currently in use:
 Open-air burning
 Fixed-facility incineration
 Air-curtain incineration
 Follow site’s fire safety procedures.
 Ensure local Fire Department is aware of any open burning.
 Wear PPE issued by your supervisor including respirator and proximity suit.
 Follow the site’s heat stress reduction plan.
 Additional training is required when using fire extinguishers.
 Air-curtains present significant risks, stay back from the edge!
Air-curtain incineration
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Rendering
 Rendering is the heating of material (carcasses) that simultaneously dries and
separates the materials. A fatty substance (such as lard grease) and ground
material is produced.
 Rendering can inactivate the AI virus.
 Rendering is a limited option as it increases the AI exposure risk for
transportation workers and rendering plant personnel, and the potential to
spread the virus to other locations.
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Burial
There are three burial techniques that may be used:
 Trench burial
 Mass burial sites
 Landfill
 Hazards associated with burial include excavation hazards and heavy
equipment issues. Know the hazards of your excavation!
 Environmental contamination may result from disposal so a disposal
decision support tool should be used when selecting burial method.
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Burial
Controlling Excavation Hazards
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Composting
Phase One:
 Biological activity breaks down
carcasses
 The temperature of the
compost pile increases and
inactivates the AI virus
 Soft tissue decomposes
 Bones partially soften
Phase Two:
 The remaining materials (mainly
bones) break down fully
 The compost turns to a
consistent dark brown to black
soil or “humus” with a musty
odor containing primarily non-
pathogenic bacteria and plant
nutrients
Carcass composting is a natural biological process.
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Question and Answer
Reflection:
What’s on your mind?
 27
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© AVT Applied Veterinary Technologies Europe AB
Address details: c/o INTRED, Södra Hamnen 2, 45142 Uddevalla, Sweden
Org.nr: 556792-1944 - Phone: +44 7452 272 358- E-mail: harm.kie@gmail.com

AVT session 2: Depopulation Strategies

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