Download - AVT session 2: Depopulation Strategies

Session 2 Depopulation strategies

Harm KiezebrinkResearch Fellow

Faculty of Veterinary Science Queensland University

© 2014 Applied Veterinary Technologies Europe AB

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Depopulation

Rapid response management

Culling Storage Transportation Composting Disposal


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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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CullingOfficial 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


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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


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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


CO2 gas stunningLarge-scale 1.100 liter containers


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CO2 gas stunningAlternative container systems


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CO2 gas stunningStable gassing


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Wet foam stunningFire 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 stockEggs and egg traysLitter and beddingsManure Organic waste products Organic building materials impossible to decontaminateDisposables used during the response operation

Contaminated materials - Organic materials & disposables -


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Managingcontaminated 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


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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


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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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BurialControlling 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?

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