How serious is the threat of an Avian flu Human Pandemic

Avian (Bird) December 2005

Avian Flu

General Background Terms

    Virus Bacteria Infection Mutation     Carrier of infection Resistance to infection Spread of infection Genetic material

Avian Flu

Historical Development Influenza Virus (worldwide problem) Types A-B-C  “HN” Classification of virus (lab testing) 

Hemagglutinin

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Neuraminidase

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1918 “Spanish” Flu (H 1 N 1 )

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Killed 50 million people worldwide

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1961 H 5 N 1 found in wild birds in South Africa

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1997 H 5 N 1 found in Hong Kong

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2003 Bird Flu re-emergence in South Asia

Avian Flu

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Mechanism of Non-Human Spread

Once spread from wild bird population to domestic birds (Chickens): a first serious step has occurred A viral “jump” to more domestic animals (horses, cats, pigs): a second serious step will have occurred This broad “mixing pot” of genetic material; makes the spread to humans more likely from such a pool of replicating gene fragments

Avian Flu

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Isolated Facts

New H 5 N 1 virus comes from mostly avian gene pool (not mammals) like the H 1 N 1 Spanish flu did (1918) 

Why has it now become lethal in some humans? Unknown!

H 5 N 1 virus remain “alive” in feces, oral droppings, contaminated water for 7-10 days Asian human H (17-31yrs) 5 N 1 infections are in younger population In south Asia, human infection has mostly involved direct, close contact with infected birds (blood, feces, feathers)

Avian Flu

Isolated Facts Cont’d  Current human Influenza A vaccine does not protect against H 5 N 1 Flu; eating “cooked” infected chickens will not cause infection  Domestic ducks can carry H 5 N 1 “silently”: so a reservoir for potential carrier of infection  Domestic chickens get “infected” from contact with shed droppings from “migratory waterfowl/ducks” The H 5 N 1 avian flu is 32 times more infective than SARS Virus (2003)

Avian Flu

Human Pandemic Requires:  Highly virulent organism  Lack of sufficient human immunity  Easy spread from human to human This is currently absent

Avian Flu

Potential Catastrophic Change

H 5 N 1 Virus “Mutates” Invades Human Cell Organ Damage Lung Heart Kidney Replicates Invades Other Cells

Avian Flu

Human Diagnosis  Spot testing  Local Labs   Reference Labs (CDC) Physicians/Hospitals

Avian Flu

Human signs and Symptoms Initial

  High fever Chest pain     Cough Weakness, muscle aches Easy bleeding Diarrhea

Late

   Pneumonia Encephalitis Kidney failure

Currently in East Asia : mortality 50 % (n=150 cases)

Avian Flu

Current Spread of Avian Disease (Asia to Europe) North to Mongolia/Siberia East Asia West to Ukraine, Croatia, Turkey

Avian Flu

Treatment

Surveillance

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China may be Ground Zero (1 st

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line of defense) 1.3 billion people 13 billion birds 75% of population live on farms Medical system weak

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Prophylaxis (For Chickens)

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Twice a year vaccines

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Bird Flu Outbreak

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Authorities kill hundreds of thousands of birds

Avian Flu

Human Treatment

Quarantine

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World health Organization (WHO)

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21 days to “control” Before disease affects 20-30 people Hard for doctor to diagnosis quickly/implement isolation Area may be as large as a city

Avian Flu

Human Treatment  Vaccine    Available for bird now In development for human Problems with application   New mutation may limit effectiveness Antivirals   Tamiflu (oral) Relenza (inhalation)  Problems with application of these meds  Not thoroughly tested   Resistance occurs Stockpilling can be disruptive

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Avian Flu Possible Global Threat

(Worst case scenario) Estimate 150 million human deaths worldwide Estimate economic cost : 800 billion dollars Theoretical terrorist operation: steal deadly viral genome harvest “live” virus in lab deliver as aerosol to unsuspecting populace

Avian Flu

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Conclusions

Far-reaching spread of deadly virus to USA (Unlikely)

Danger of H 5 N 1 reaching USA is real

 Interconnected world (infection carriers) Wild birds (could first reach Alaska & Canada) Human travelers (a flight away)

No intervention has been successful stopping a pandemic once it starts

Avian Flu

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Conclusions

Surveillance, global cooperation, vaccination, antiviral agents,quarantine, infected chicken elimination will prevent epidemic spread in USA Gene Mutation and Viral human to human spread is random and cannot be controlled SO viral illnesses are a stark reality we have to fight