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Control of Highly Pathogenic Avian Influenza (HPAI) in Poultry

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Learning Objectives

• Understand how Influenza A is spread in poultry

• Understand how highly pathogenic avian influenza outbreaks happen\

• Know how to detect and control highly pathogenic avian influenza outbreaks via multiple measures

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Session Outline• Influenza A and highly pathogenic

avian influenza (HPAI) in birds• How to prevent or control HPAI among

poultry– Decontamination– Surveillance and biosecurity– Vaccines

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Influenza Virus

Type A most likely to cause a panzootic

• Most likely to change

• Different strains mix in one animal or human host (reassortment)

• People lack immunity to the resulting new subtype (highly pathogenic)

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Influenza A• Infects many birds, animals, humans

– Water fowl and poultry– Humans (mixing vessels)– Pigs (mixing vessels)– Other mammals

• Subtypes based on “HA” and “NA” surface proteins – 16 HA, 9 NA subtypes exist– H1N1, H1N2, H3N2 are circulating human

subtypes

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HumanHuman virusvirus

ReassortantReassortantvirusvirus

Non-humanNon-humanvirusvirus

Transmission of Influenza Transmission of Influenza AA

16 HAs16 HAs9 NAs9 NAs

DIRECTDIRECT

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How does HPAI happen?

• Carried by migrating wild birds to domestic poultry

• Virus changes and becomes more deadly in poultry

• Difficult to control and eliminate because it spreads rapidly

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Signs of Infection in Birds• Wild waterfowl asymptomatic

• Domestic ducks recently found to be asymptomatic

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Signs of Infection in Birds• Mildly ill birds

– Ruffled feathers– Fewer eggs– Breathing problems

• Very ill birds – May have bleeding under skin of the legs– May have swollen eyes, wattle– Usually die within 2 days

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How Birds Spread HPAI

• Direct contact– Feces

– Respiratory secretions

• Improperly disposed carcasses

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How Humans Spread HPAI • Hands• Fomites• Airborne particles

• Contaminated equipment

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How to Prevent or Control Highly Pathogenic Avian Influenza

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Potential Control Measures• Surveillance

• Biosecurity

• Restricting movement of birds

• Destroying birds humanely

• Disposing of carcasses properly

• Vaccines

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Disease Surveillance• Purpose

– Rapidly detect and respond to disease– Learn about virus mutations

• Methods– Country-specific, depending on risk– Signs and symptoms reporting– Serologic surveys– Sentinel surveillance

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Increasing Surveillance Effectiveness

• Make HPAI a notifiable disease

• Establish a formal system to detect and investigate outbreaks

• Develop technical capability to diagnose HPAI in your country / region

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Increasing Surveillance Effectiveness (cont’d)

• Participate in the regional surveillance and diagnostic network

• Conduct surveillance at a minimum of every six months

• Monitor medical status of outbreak control workers

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Disease Surveillance• In areas where HPAI is documented

• In areas where HPAI could appear

• Sensitize and educate the community– Poultry die offs– How to report to animal health authorities– Why to report (and any incentives)

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Disease Surveillance

Rapid reporting enables animal health agents and rapid response teams to:

• Investigate and record key information

• Analyze specimens

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BiosecurityAll measures taken:

• To keep disease out of a farm

• To keep disease from spreading from an infected farm

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Ensuring Biosecurity

• Maintain a barrier from the outside world

• Separate new poultry for 2 weeks

• Prevent unknown birds from entering flock

• Control human traffic into the farm

• Use “all in – all out” production

Note: Infected poultry and poultry products do NOT enter the food supply.

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Poultry-Raising and BiosecuritySecurity Marketing

Sector 4 Backyard poultry Products consumed locally

Sector 3 Low to minimum Products enter live bird markets

Sector 2 Moderate to high Products often marketed commercially

Sector 1 High Products marketed commercially

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Restricting Movement and Mixing

• Farm movement control– Birds– People– Objects

• Bird markets – Close– Depopulate– Disinfect

• Border patrolsDeutsche Presse-Agentur

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Destruction and Disposal of Birds in Affected Areas

• Kill birds humanely– Consider compensation for

farmers

• Dispose carcasses safely– Do NOT contaminate local

water sources

• Clean and disinfect

• Restock after 21 days– Only after official inspection

3/1/2006 Reuters. Karachi

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Poultry Vaccines

Advantages:• Inactivated (killed) whole AI virus available• Effective against H5 subtype• Good resistance to infection• Reduced amount of virus in environment

Disadvantages:• Administered by injection• Does not eliminate possibility of infection

Potential future vaccine:• New recombinant fowlpox vaccine

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Summary• Target high risk

flocks

• Isolate domestic birds from wild water fowl

• Consider compensation to encourage early reporting

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Glossary

Highly Pathogenic Avian Influenza (HPAI)Influenza infection in poultry that causes severe illness and often death. Can be transmitted to humans resulting in severe illness or death.

Panzootic A disease affecting animals of many species, especially over a wide geographic area.

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GlossaryDisease SurveillanceThe ongoing systematic collection and analysis of data and the provision of information which leads to action being taken to prevent and control a disease.

Sentinel SurveillanceDisease surveillance based on selected population samples chosen to represent the relevant experience of particular groups.

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References and Resources• Guiding principles for Highly Pathogenic Avian

Influenza Surveillance and Diagnostic Networks in Asia. FAO Expert meeting on Surveillance and Diagnosis of Avian Influenza. Bangkok, Thailand, 21-23 July, 2004. http://www.fao.org/ag/AGAinfo/subjects/en/health/diseases-cards/Guiding%20principles.pdf

• Preparing for Highly Pathogenic Avian Influenza: A Manual for Countries at Risk . V. Martin, A. Forman, J. Lubroth. Updated 16 February 2006 http://www.fao.org/docs/eims/upload/200354/HPAI_manual.pdf

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References and Resources• A Global Strategy for the Progressive Control of

Highly Pathogenic Avian Influenza (HPAI) . Food and Agriculture Organization, World Organisation for Animal Health, World Health Organization http://www.fao.org/ag/againfo/subjects/documents/ai/HPAIGlobalStrategy31Oct05.pdf

• PROTECT POULTRY – PROTECT PEOPLE Basic advice for stopping the spread of avian flu. Emergency Centre for Transboundary Animal Diseases. FAO, Agriculture Department, Animal Production and Health Division http://www.fao.org/docs/eims/upload//207623/FAO_HPAI_messages.pdf

• Additional FAO Animal Health Information Resources Available at: http://www.fao.org/ag/againfo/subjects/en/health/diseases-cards/avian_recomm.html