Influenza

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  • 9
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  • Influenza

    1. 1. Influenza V.Biaukula
    2. 2. Influenza Virus Subtypes • Influenza A • Influenza B • Influenza C Annual Epidemics Pandemic
    3. 3. Structure of influenza virus Two surface antigens HA (hemagglutinin) NA (neuraminidase)
    4. 4. Why influenza epidemics every year? • ‘Antigenic drift’ - Minor changes in surface antigen - No protection from previous immunity
    5. 5. Subtypes of Influenza A Virus (Karl G Nicholson, et al Lancet 2003; 362: 1733-45) •Many subtypes (H and N) •3 subtypes have caused human epidemics •H1N1 •H2N2 •H3N2 H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H12 H13 H14 H15 H11 N1 N2 N3 N4 N5 N6 N7 N8 N9
    6. 6. Avian Influenza (H5N1) • 1st seen in 1997 • History of contact to dead/sick poultry • Highly pathogenic (Case Fatality Rate 60%) • Most cases seen in children and adults <40yrs, most deaths in 10-19 yr old.
    7. 7. Avian Influenza (Bird flu) Year Cases Deaths 2003 4 4 2004 46 32 2005 98 43 2006 115 79 2007 88 59 2008 44 33 2009 73 32 2010 31 13 Total 500 295
    8. 8. Influenza Pandemics
    9. 9. Influenza Pandemics cause high morbidity & mortality A(H1N1) A(H2N2) A(H3N2) 1918 1957 “Hong Kong Flu” 20 - 40 m deaths 1 - 4 m deaths 1 - 4 m deaths Credit: US National Museum of Health and Medicine “Spanish Flu” “Asian Flu” 1968
    10. 10. INFLUENZA PANDEMIC in the PACIFIC ISLAND HISTORY - 1918 Some Pacific Islands amongst the worst affected: 1/3 to ½ of the pop. affected & ¼ died in some PICTs Samoa (22% pop. Killed -7542 deaths), Fiji (5% ~9000), Tonga (6%), Nauru (6%) French Polynesia: Tahiti (25%) Guam (5%) Others were totally spared: American Samoa (strict maritime quarantine) Kiribati, Tuvalu, Solomon Islands & Vanuatu (Australian quarantine policy for outgoing steamships exclusively servicing these islands)
    11. 11. • 1st wave generally mild • Historically 2nd wave associated with greater morbidity and mortality. • Pandemics occur when a novel virus infects a community
    12. 12. Pandemic H1N1 • As of 12 July lab confirmed cases in 214 WHO member states; 18337 deaths • World wide pandemic activity is low.
    13. 13. Nasophaeyngeal swab to confirm influenza • Must be collected within 3 days of onset of symptoms • Must have fever with cough or sore throat.
    14. 14. Critical issues for Infection control • Avoid crowding patients together, promote distance between patients • Protect mucosa of mouth and nose • Perform hand hygiene
    15. 15. Standard precautions • Hand hygiene • Respiratory hygiene/cough etiquette • Avoid touching your face
    16. 16. Environmental cleaning • Environmental surfaces to be kept clean; wipe with Sodium hypochlorite 1% (Janola). Also hydrogen peroxide, chlorine, detergents, iodine based antiseptics and alcohols. • Influenza can survive on environmental surfaces:2-8hours
    17. 17. Pandemic (H1N1) 2009 Clinical management
    18. 18. Influenza Like Illness (ILI) •Sudden onset of fever (38ºC or higher, if no thermometer available, reported chills or high temperature) •At leas one of the following symptoms: cough, sore throat, runny nose, nasal congestion; in the absence of alternative diagnosis.
    19. 19. Severe Acute Respiratory Illness (SARI) • Meets ILI case definition AND • Shortness of breath or difficulty breathing AND • Requiring hospital admission.
    20. 20. High risk group for severe disease • 3rd trimester pregnancy, under 2yrs, 65+ yrs, diabetics, long term steroid therapy, chronic lung and heart disease, hematological disorder. • Neurological disorders can increase risk of severe disease in children. • Large proportion of severe & fatal cases: obese & morbidly obese, ye obesity hasn’t been recognized as a risk factor.
    21. 21. • Majority have uncomplicated ILI, recovery within a week, even with no medical Rx. • Severe cases deteriorate about day 3 to 5 • Rapid deterioration, many progress to respiratory failure within 24 hours – require IMMEDIATE ICU admission.
    22. 22. Treatment • Oseltamivir (Tamiflu): used in cases with high risk of severe disease • Rx must be started early to reduce disease severity & improve survival chances, even without confirmatory test. • Paracetamol, Vit. C, Increase fluid intake
    23. 23. Vaccination • Most effective preventive tool • May prove less effective if virus evolves rapidly, and virus may get around growing immunity in the population.
    24. 24. Must remain alert • Second wave may or may not occur • Pandemic continues, virus may evolve without it being possible to predict when.
    25. 25. References • http://www.cdc.gov/flu/avian/outbreaks/cur rent.htm • http://www.who.int/csr/don/2010_07_16/en /index.html

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