2009 Influenza A(H1N1) – Human Swine Flu Is this the pandemic?

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Allison McGeer, MSc, MD, FRCPC

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  • 2009 Influenza A(H1N1) – Human Swine Flu Is this the pandemic?

    1. 1. 2009 Influenza A(H1N1) – Human Swine Flu Is this the pandemic? Allison McGeer, MSc, MD, FRCPC Mount Sinai Hospital University of Toronto
    2. 4. Nasal Congestion Sore Throat Muscle Pains Headache Cough Malaise Infectious Clinical Characteristics of Seasonal Influenza Infection Days After Onset 0 1 2 3 4 5 6 7 8 Nöel GE. Life-threatening “flu”? Can J Diagnosis 1999;Mar Fever
    3. 5. Be an influenza virus, see the world
    4. 6. Changes in Influenza Viruses <ul><li>Antigenic drift (continuous mutation) </li></ul><ul><ul><li>minor changes in A & B strains, s ame subtype </li></ul></ul><ul><ul><li>every year while virus is in humans </li></ul></ul><ul><li>Antigenic shift (recombination with non-human viruses) </li></ul><ul><ul><li>produce new subtype with changed H and/or N </li></ul></ul><ul><ul><li>population has no immunity to this new virus </li></ul></ul>
    5. 7. Human virus Reassortant virus Avian virus 16 HAs 9 NAs Mechanisms of Antigenic Shift Swine virus
    6. 8. 2009 H1N1 influenza A <ul><li>April 10-15 </li></ul><ul><ul><li>Mexican authorities recognize increase in acute respiratory disease/pneumonia, especially in young adults </li></ul></ul><ul><li>April 17 </li></ul><ul><ul><li>US recognizes new influenza strain, mostly derived from pigs (a “swine” flu), in two unrelated children in California </li></ul></ul>
    7. 10. 2009 A(H1N1) – Human Swine flu Disease <ul><li>Symptoms – typical influenza </li></ul><ul><li>Fever (>90%) </li></ul><ul><li>Cough (>90%) </li></ul><ul><li>“ Prostration” </li></ul><ul><li>Nasal congestion </li></ul><ul><li>Sore throat (66%) </li></ul><ul><li>Diarrhea (25%) </li></ul><ul><li>Vomiting (25%) </li></ul><ul><li>Provisos </li></ul><ul><li>Almost certainly, milder disease occurs </li></ul><ul><li>More severe disease likely won’t present “typically” </li></ul>
    8. 11. <ul><li>How severe is it? </li></ul><ul><ul><li>WHO totals: 61 deaths / 5728 cases </li></ul></ul><ul><ul><li>Case fatality rate=1% </li></ul></ul>2009 A(H1N1) – Human Swine flu Disease
    9. 13. <ul><li>How severe is it? </li></ul><ul><ul><li>WHO totals: 61 deaths / 5728 cases </li></ul></ul><ul><ul><li>Case fatality rate=1% </li></ul></ul><ul><ul><li>WHO Rapid Pandemic Assessment Collaboration (Science 11 May) </li></ul></ul><ul><ul><ul><li>Case fatality rate: 0.4% (0.3-1.5%) </li></ul></ul></ul><ul><ul><ul><li>0 (U95%CL 0.6%) </li></ul></ul></ul>2009 A(H1N1) – Human Swine flu Disease
    10. 14. <ul><li>No – not quite “humanized” </li></ul><ul><li>Yes – and “first wave” will start in the next few weeks </li></ul><ul><li>Yes – but “first wave” won’t start until sometime in the fall </li></ul>2009 A(H1N1) – Human Swine flu Is it the next pandemic?
    11. 15. So, what are we doing in hospitals? <ul><li>Brushing off our pandemic plans, and activating phase 5 </li></ul><ul><li>Filling in the gaps </li></ul><ul><li>Recognizing that the pressure in ICUs may be less than anticipated, but the workload in ED and primary may be higher </li></ul>

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