How serious is the threat of an avian flu human pandemic
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How serious is the threat of an Avian flu Human Pandemic . Avian (Bird) December 2005. Virus Bacteria Infection Mutation. Carrier of infection Resistance to infection Spread of infection Genetic material. Avian Flu . General Background Terms . Avian Flu. Historical Development

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Virus

Bacteria

Infection

Mutation

Carrier of infection

Resistance to infection

Spread of infection

Genetic material

Avian Flu

General Background Terms


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Avian Flu

Historical Development

Influenza Virus (worldwide problem)

Types A-B-C

  • “HN” Classification of virus (lab testing)

    • Hemagglutinin

    • Neuraminidase

  • 1918 “Spanish” Flu (H1N1)

    • Killed 50 million people worldwide

  • 1961 H 5N1 found in wild birds in South Africa

  • 1997 H5N1 found in Hong Kong

  • 2003 Bird Flu re-emergence in South Asia


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Avian Flu

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


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Avian Flu

Isolated Facts

New H5N1 virus comes from mostly avian gene pool (not

mammals) like the H1N1 Spanish flu did (1918)

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

  • H5N1 virus remain “alive” in feces, oral droppings, contaminated water for 7-10 days

  • Asian human H5N1 infections are in younger population (17-31yrs)

  • In south Asia, human infection has mostly involved direct, close contact with infected birds (blood, feces, feathers)


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    Avian Flu

    Isolated Facts Cont’d

    • Current human Influenza A vaccine does not protect against H5N1

      Flu; eating “cooked” infected chickens will not cause infection

    • Domestic ducks can carry H5N1 “silently”: so a reservoir for potential carrier of infection

    • Domestic chickens get “infected” from contact with shed droppings from “migratory waterfowl/ducks”

      The H5N1 avian flu is 32 times more infective than SARS Virus (2003)


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    Avian Flu

    Human Pandemic Requires:

    • Highly virulent organism

    • Lack of sufficient human immunity

    • Easy spread from human to human

      This is currently absent


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    Avian Flu

    Potential Catastrophic Change

    H 5 N1 Virus Invades Human Cell

    Replicates

    Organ Damage Invades Other Cells

    Lung

    Heart

    Kidney

    “Mutates”


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    Avian Flu

    Human Diagnosis

    • Spot testing

    • Local Labs

    • Reference Labs (CDC)

    • Physicians/Hospitals


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    Initial

    High fever

    Chest pain

    Cough

    Weakness, muscle aches

    Easy bleeding

    Diarrhea

    Late

    Pneumonia

    Encephalitis

    Kidney failure

    Avian Flu

    Human signs and Symptoms

    Currently in East Asia : mortality 50 %

    (n=150 cases)


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    Avian Flu

    Current Spread of Avian Disease (Asia to Europe)

    North to Mongolia/Siberia

    East Asia

    West to Ukraine, Croatia,

    Turkey


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    Avian Flu

    Treatment

    Surveillance

    • China may be Ground Zero (1st line of defense)

      • 1.3 billion people

      • 13 billion birds

      • 75% of population live on farms

      • Medical system weak

    • Prophylaxis (For Chickens)

      • Twice a year vaccines

    • Bird Flu Outbreak

      • Authorities kill hundreds of thousands of birds


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    Avian Flu

    Human Treatment

    Quarantine

    • World health Organization (WHO)

      • 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


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    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


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    Avian Flu

    Conclusions

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

    • Danger ofH5N1reaching 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


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    Avian Flu

    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


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