Avian Influenza Animal Control and · Planning for Culling When planning to AI disposed poultry, the following should be considered: – Minimising handling and movement of animals

Animal Control and Vaccinations

Dr. Pravit Choomkasien, DVM.

Avian Influenza

Learning Objectives

1. Control of Infected poultry• Process for culling• Safety of personnel• Chemical disinfection and sanitation measure

2. Vaccination for Prevention• Overview of AI Vaccine• Advantage and disadvantage of AI vaccination• Administration of AI Vaccine• Recommendation made when AI is detected in

vaccinated flock

Culling Infected Animals

Planning for CullingWhen planning to AI disposed poultry, the following should be considered:

– Minimising handling and movement of animals – Culling the animals on the affected premises– The species, number, age and size of animals to be

culled, and legal issues involvement– Methods of culling the animals, and their cost – Destruction after culling – The health and safety of personnel conducting the

culling (PPE) – The presence of other nearby premises holding

animals.

Methods Used for culling of Poultry

Method UseDislocation of the neck Both large and small numbers of

birds such as fancy breeds or pigeons

Decapitation Small numbers of poultry conducted in an a defined area to prevent contamination

Put the live birds in the without any treatment sags

Both large and small numbers of birds in areas where further contamination will not occur

Burning or Burying

Gaseous agents Large numbers of birds such as in poultry units

Dislocation of the Neck(Un-humane culling)

• Manual – one stretch or bend of the neck to sever spinal cord

• Mechanical – pliers crush cervical vertebrae and cause damage to spinal cord– Depending upon the type

of poultry, the following tools can be used:

• Pliers• Burdizzo• Bone cutters• Secateurs

(Not applicable)

Decapitation(Un-humane culling)

• Animals should be restrained• Removal of the head should occur

quickly, using a sharp blade or guillotine– Technique is quick and easy– Death is not immediate– Blood may contaminate area and therefore

proper disinfection is needed

(Not applicable)

Carbon Dioxide Gas(Humane culling)

1. Place in air-filled container– 30% = loss of consciousness– At least 3 minutes

2. Remove after unconsciouness– Cervical dislocation or exsanguination

3. Exposure for 20-30 minutes– Death in neonatal or juevenile– Can be filled in advance to accelerate anesthesia

4. If no CO2 available, use dry ice– Placed in container, under gauze floor– Animals placed in container, until unconsciouness or

dead

(Not applicable)

Alternate Gaseous Agents(Humane culling)

• Gaseous anesthetic agents– halothane, enflurane and isoflurane– piped into container or on wool/gauze at the bottom of

container– expensive and should be conducted in well-ventilated room– ether not recommended

• Hydrogen cyanide gas– safety concerns restrict use

• Carbon monoxide– Readily available, but fumes must be cooled

• Methyl bromide– Is also capable of neutralizing or destroying virus, but

environmental concerns restrict its use

(Not applicable)

Carcasses destruction after culling

Burning : Small numberBurying : Both small and large

number (by Hoe or Backhoe)

Safety Burying1. Hole should be located far

from well, pond, or other animals

2. Hole should be at least 1 meter deep

3. Quicklime should be added to the bottom and borders of the hole.

4. Place all birds and other contaminated objects in the hole

5. Cover with quicklime6. Cover with earth or topsoil

Animal Vaccinations for Avian Influenza

Overview of Vaccines

Tested and available:• Inactivated (killed) whole AI virus• Good efficacy against H5 subtype• Good resistance to infection• Reduced amount of virus in environment• Administered by injection• Differentiating Infected from Vaccinated Animals

Potential future vaccine:• New recombinant fowlpox vaccine

Inactivated Vaccines• Homologous –

– Contains same strain as virus in the field– Field tested in Mexico/Pakistan

• Prevents clinical disease• Reduces amount of virus shed into environment

– Impossible to differentiate vaccinated from field-exposed

• Heterologous –– Contains same strain, but has a heterologous

neuraminidase– Same clinical and shedding results, but

• antibodies against neuraminidase create field marker

Commercial AI Vaccine for Poultry (at present available)

• Gallumine Flu (H5N9) from Merial comp. France

• Nobilis influenza (H5N2) From IntervetComp. Netherland

• Poulvac I AI (H5N9) From Fort Dodge Comp. USA

• AI Vaccine H5N1 (No detail) China

Differentiating Infected from Vaccinated Animals

• Same haemagglutinin (H) as challenge virus• Different neuraminidase (N)Results:

– Homologous H group = clinical protection of 93%, regardless of vaccine scheme

– Serological survey showed almost perfect agreement with sensitivity = 98.1 and specificity = 95.7 respectively

– Could be an effective strategy to control AI infections in poultry

Source: Avian Pathology (2002) 32, 47-55

Recombinant Vaccines1. Utilizes bacteria or yeast to produce large quantities of

a single viral protein2. Protein then purified and injected into animal, which

develops antibodies against the protein causing protection from the disease

• NOTE: Currently only licensed and field tested in Mexico, using a fowlpox virus expressing the H5 antigen

Results of Recombinant Study - Mice

• Genetically engineered adenovirus to express all or parts of avian influenza hemagglutinin (HA) on its surface

• Based upon sequenced strain of H5N1 from Vietnam

Source: Journal of Virology, February 15, 2006

Vector Results

Adenovirus: no H5N1 genes (empty vector)

•3 Days - Substantial weight loss•6-9 Days – All mice dead

Adenovirus w/ wild-type H5N1

•Mild and short lived weight loss•All mice survived infection

Results of Recombinant Study - Chickens

Source: Journal of Virology, February 15, 2006

Vector Results

Adenovirus: no H5N1 genes (empty vector)

•All chickens died within 2 days of exposure

Adenovirus w/ wild-type H5N1: Subcutaneously

•All chickens survived exposure and developed strong HA antibody response

Adenovirus w/ wild-type H5N1: Intranasally

•Half of the chickens died and half survived

Poultry Vaccination Schedule -Minimum age for first injection

Second shot

Emergency All poultry, regardless of age

4-6 weeks later

Replacement Flocks(High Risk Areas)

At birth 4-6 weeks (1st)16-18 weeks (2nd)

Replacement Flocks (Low Risk Areas)

4 weeks 16-18 weeks

Layers 8 days 36 days

Broilers*** 8 days Should not given

***Vaccination of broiler chickens in principle is discouraged, as there isn’t sufficient time to develop adequate immunity

Sample Vaccination Schedule –Geese and Ducks

Minimum age for first injection

Second shot

Duck ready for foie grasproduction

3 weeks 4 weeks later

Geese 4 weeks 3 weeks later

Other ducks 3 weeks 4 weeks later

The second shot is not carried out on birds due to leave the farm during the week scheduled for the second shot

Notes:The first infection is not given to the birds in the month prior to their departure from the farm

Source: Official Journal of the EU, 25.2.2006, L 55/51

Vaccine Strategies• Stamping-out – destruction of all poultry in a

defined area (1km to >10 km) and “at risk”farms

• Vaccination areas – well defined, manageable zones that are as self contained as possible, limiting the need to transfer poultry across borders

• Monitoring – assessment of vaccination should be done one month after 2nd

vaccination. Serological methods may vary.

Vaccine Strategies for Different Situations

H5/H7 virus pathogenicity

Index case flock

Evidence of spread to industrial

sector

Population in density

area

Policy

HPAI/LPAI Backyard No High/Low Stamping-out

HPAI/LPAI Backyard Yes LowHigh

Stamping-outVaccination

HPAI/LPAI Industrial No High/Low Stamping-out

HPAI/LPAI Industrial Yes LowHigh

Stamping-outVaccination

Source: OIE 71 SG/12/CS3 E: The Use of Vaccination as an Option for Control of Avian Influenza

Monitoring Measures

Actions when a Case is Detected in a Vaccinated Flock

• Immediate quarantine of infected site• Depopulation of flock, preferably with disposal of the

birds on site (burial)• Disposal of litter, onsite to limit risk of spread

– Burial– Piles covered with resistant sheet of plastic

• Eggs, egg-trays, animal feed, etc. should be destroyed• Intensified surveillance

– 3-5 km. radius– Sudden mortality of sentinels should be investigated

• Limit movement of poultry and poultry-related products for at least 21 days after cleaning/disinfection of site

Source: Guidelines for the Administration of Nobilis Influenza H5 Vaccine as Part of an Avian Influenza Strategy

Advantage and Disadvantage of AI Vaccine

Advantage Disadvantage• Reduce susceptibility to infection• Reduce duration of virus shedding• Reduce viral Load in the environment• Good for layers and breeders flocks

• Difficult to diagnose when human case occurred.• Cannot differentiate of infected poultry if no sentinel birds• Much more works for monitoring• Not good for broiler flocks

Vaccination Versus Culling

Vaccination Culling• good for disease free area for layers and breeders flocks•good for precious fancy or sporting birds•Not valid for backyard poultry•More work loads (monitoring) after vaccination

• good for outbreak area.•Not valid for precious fancy or sporting birds.•More expence for conpensation

DiscussionBiosecurity is more valid

• Evapulate Farms.(Air Conditioned)

• Good pest control• Transportation control.

(antisepltic ordisinfectant must be used when come in and go out) vehicles, man, egg trays. equipments, etc.

• Decontaminated feed.• Safety water consumption

Resources• WHO interim recommendations for the protection of persons involved

in the mass slaughter of animals potentially infected with highly pathogenic avian influenza viruses, 26 January 2004

• Prevention and Control of Avian Flu in small scale poultry: A guide for veterinary paraprofessionals in Vietnam.

• Commission Decision on introducing preventative vaccination against highly pathogenic avian influenza H5N1 and related provisions for movements in France, Official Journal of the European Union

• Development of a DIVA (Differentiating Infected from Vaccinated Animals) strategy using a vaccine containing a heterologousneuraminidase for the control of avian influenza, Avian Pathology (2002), 32, 47-55

• Protection of Mice and Poultry from Lethal H5N1 Avian Influenza through Adenovirus-Based Immunization, Journal of Virology

• Guidelines for the Administration of Nobilis Influenza H5 Vaccine as Part of an Avian Influenza Strategy, Intervet

Avian Influeuza “Man to Man”. The emerging severe and high fatal disease of the 21 Century.

It will be pandemic not solong from now.

But no onecan know when……That it is of all conccrns such a very

serious human disaster.