Avian Influenza – What does it all mean? Important Background Information Island Paravets and Residents

Avian Influenza –Avian Influenza –What does it all What does it all

mean?mean?

Important Background Important Background Information Island Paravets Information Island Paravets

and Residentsand Residents

Avian Influenza:Avian Influenza: BackgroundBackground

Waterbirds are the natural reservoir of Waterbirds are the natural reservoir of all Influenza “A” viruses. Wild birds all Influenza “A” viruses. Wild birds and these diseases have evolved and these diseases have evolved together naturally over timetogether naturally over time

Many subtypes of AI already exist in Many subtypes of AI already exist in wild bird populations in North America wild bird populations in North America – but currently not HPAI H5N1– but currently not HPAI H5N1


Source: Horimoto and Kawaoka, 2005.

H = hemagglutinin (16 types)N = neuraminidase (9 types)

Influenza strains are named for their specific types of protein spikes that act as a “lock and key” mechanism with host cells

HH55NN11is one of the 144 is one of the 144

possible possible combinations. One combinations. One

subtype (HPAI subtype (HPAI H5N1) is of concern H5N1) is of concern

worldwide.worldwide.


PathogenicityPathogenicity refers to the ability of the refers to the ability of the virus to produce disease and is based virus to produce disease and is based on the impacts to domestic poultryon the impacts to domestic poultry Low pathogenicLow pathogenic = few clinical signs, mostly = few clinical signs, mostly

respiratory and digestive problemsrespiratory and digestive problems High pathogenicHigh pathogenic = attack many organs, can = attack many organs, can

cause high mortalitycause high mortality

HPAI = kills >75% of chickensHPAI = kills >75% of chickens

AI viruses can become very pathogenic AI viruses can become very pathogenic when they enter a new host (domestic when they enter a new host (domestic poultry, humans, some carnivores). poultry, humans, some carnivores). This is the suspected origin of HPAI This is the suspected origin of HPAI strains.strains.

Significant Variation within Significant Variation within current HPAI H5N1 subtypescurrent HPAI H5N1 subtypes

Juvenile mallards were inoculated with 23 Juvenile mallards were inoculated with 23 different isolates of HPAI H5N1different isolates of HPAI H5N1

Results ranged from no clinical signs (n=8 Results ranged from no clinical signs (n=8 virus isolates) to high lethality in inoculated virus isolates) to high lethality in inoculated ducklingsducklings

22/23 virus isolates were efficiently 22/23 virus isolates were efficiently transmitted from inoculated ducklings to transmitted from inoculated ducklings to susceptible contacts susceptible contacts

Sturm-Ramirez et al. 2005Sturm-Ramirez et al. 2005


HPAI H5N1 is spreading rapidly across the HPAI H5N1 is spreading rapidly across the globeglobe

HPAI H5N1 has killed 132 out of 230 people HPAI H5N1 has killed 132 out of 230 people infected (57%)infected (57%)

If If avianavian influenza combines genetically with influenza combines genetically with humanhuman influenza it can become very influenza it can become very infectious among humansinfectious among humans

The risk of H5N1 changing to become global The risk of H5N1 changing to become global pandemic influenza is unknownpandemic influenza is unknown

Why are we so worried about Why are we so worried about “bird flu”?“bird flu”?



Avian Influenza:Avian Influenza: Current SituationCurrent Situation

HPAI H5N1 Human cases HPAI H5N1 Human cases Dec. 2003 to May 2006Dec. 2003 to May 2006

CountryCountry CasesCases DeathsDeaths PopulationPopulationIndonesiaIndonesia 3232 2424 207 million 207 millionThailandThailand 2222 1414 65 million 65 millionVietnamVietnam 93 93 4242 84 million 84 million

147147 8080 356 million 356 million

Average = 1 case per 2.4 million people Average = 1 case per 2.4 million people Average = 1 death per 4.5 million peopleAverage = 1 death per 4.5 million people


Compared to 230 human cases of HPAI Compared to 230 human cases of HPAI H5N1 H5N1 worldwideworldwide in nearly a decade….. in nearly a decade…..

Each year in the Each year in the U.S.U.S. 5-20% of the 5-20% of the population will get population will get HUMANHUMAN seasonal flu seasonal flu

> 200,000 people hospitalized> 200,000 people hospitalized ~ 36,000 people die ~ 36,000 people die

Almost all human Almost all human infections have resulted infections have resulted

from direct contact w/ live from direct contact w/ live or dead domestic poultryor dead domestic poultry


Avian Influenza:Avian Influenza: Current Current SituationSituation

Infected People

How could HPAI H5N1 reach islands ?How could HPAI H5N1 reach islands ?

Wild Birds

Commercial /Illegal Trade of Birds, Poultry Meat, Eggs

Efforts to “stamp out” HPAI H5N1 in Efforts to “stamp out” HPAI H5N1 in Asia and Europe proving to be difficultAsia and Europe proving to be difficult

Culling infected flocksCulling infected flocks Quarantine infected areasQuarantine infected areas Enclosing poultry operationsEnclosing poultry operations Vaccinating birdsVaccinating birds

Avian Influenza:Avian Influenza: What You Should What You Should KnowKnow Reporting mortalities -> Culling -> Loss of Reporting mortalities -> Culling -> Loss of

income unless governments compensate income unless governments compensate farmers for culled poultryfarmers for culled poultry

Compensation for flocks is essential for Compensation for flocks is essential for accurate reporting accurate reporting

Sale or Sale or slaughter of sick slaughter of sick birds is known birds is known to spread HPAI to spread HPAI in Asiain Asia

Avian Influenza:Avian Influenza: What is Your What is Your Role?Role?

Be “eyes and ears” of animal health Be “eyes and ears” of animal health authoritiesauthorities

Keep informed about AI via the internetKeep informed about AI via the internet Become connected with those on- and Become connected with those on- and

off-island who will make decisions off-island who will make decisions about responding to HPAIabout responding to HPAI

Know how to respond appropriatelyKnow how to respond appropriately Communicate effectively with the Communicate effectively with the

public and government about risks and public and government about risks and realities of HPAI H5N1realities of HPAI H5N1

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Avian Influenza – What does it all mean? Important Background Information Island Paravets and Residents