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Avian Influenza and the Threat of an Impending Pandemic

Avian Influenza and the Threat of an Impending Pandemic. Eden V. Wells, MD, MPH Michigan Department of Community Health. Influenza Strains. Type A Infects animals and humans Moderate to severe illness Potential epidemics/pandemics Type B Infects humans only Milder epidemics

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Avian Influenza and the Threat of an Impending Pandemic

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  1. Avian Influenza and the Threat of an Impending Pandemic Eden V. Wells, MD, MPH Michigan Department of Community Health

  2. Influenza Strains • Type A • Infects animals and humans • Moderate to severe illness • Potential epidemics/pandemics • Type B • Infects humans only • Milder epidemics • Larger proportion of children affected • Type C • No epidemics • Rare in humans Source: CDC

  3. A’s and B’s, H’s and N’s • Classified by its RNA core • Type A or Type B influenza • Further classified by surface protein • Neuraminidase (N) – 9 subtypes known • Hemagluttin (H) – 16 subtypes known • Only Influenza A has pandemic potential

  4. Type of nuclear material Neuraminidase Hemagglutinin A/Moscow/21/99 (H3N2) Virus type Geographic origin Strain number Year of isolation Virus subtype Influenza Virus Structure

  5. Differentiating Influenza • Seasonal • Caused by influenza A or B strains circulating in humans • ~36,000 human deaths annually in USA • Avian • Caused by Influenza A • Shorebirds and water fowl are the reservoir and rarely see outbreaks, except in current H5N1 strain • Domestic poultry (chickens and turkeys), causes morbidity and mortality with outbreaks annually worldwide • Pandemic • When new virus strain occurs • Humans lack immunity • Simultaneous epidemics worldwide • Disease easily transmitted between people • Significant number of illness and deaths

  6. Influenza A: Antigenic Drift and Shift • Hemagglutinin (HA) and neuraminadase (NA) structures can change • Drift: minor point mutations • associated with seasonal changes/epidemics • subtype remains the same • Shift: major genetic changes (reassortments) • making a new subtype • can cause pandemic

  7. Seasonal Influenza • October to April • People should get flu vaccine • Children and elderly most prone • ~36,000 deaths annually in U.S.

  8. Seasonal Effects

  9. Seasonal Influenza Surveillance

  10. Avian InfluenzaThe “Bird Flu” Images from: http://www.usda.gov/oc/photo

  11. Avian Influenza • Infection can be in two forms • “low pathogenic” (LPAI) - causes mild illness and may go undetected • “highly pathogenic” (HPAI) - affects multiple organs, spreads rapidly among birds, causes high mortality very quickly

  12. Avian Influenza and Domestic Poultry • Virus is shed in saliva, nasal secretions, and feces of infected birds • Virus can survive for long periods in feces, water, and even on the ground, especially when environmental temperatures are low • Avian influenza is a reportabledisease in Michigan

  13. The Role of Animals in Influenza A Infection Mammals Domestic Birds Shore Birds and Wild Waterfowl Humans

  14. Afghanistan Albania Azerbaijan Burkina Faso Cameroon Cambodia China Cote d’ Ivoire Cyprus Denmark Dijbouti Egypt France Germany Hungary India Indonesia Iraq Israel Japan Jordan Kazakhstan Laos Malaysia Myanmar Niger Nigeria Countries with H5N1 in Poultry(OIE, 8/22/06) • North Korea • Pakistan • Palestian Aut. Territories • Romania • Russia • Serbia and Montenegro • South Korea • Sudan • Sweden • Thailand • Turkey • Ukraine • Vietnam

  15. Domestic Poultry Surveillance • Michigan veterinarians are responsible for overall livestock and poultry reportable disease programs • They conduct investigations into reports of diseases such as: • Avian influenza • Rabies • Eastern equine encephalitis • Equine infectious anemia • Tuberculosis • Psittacosis www.michigan.gov/MDA

  16. H5N1 in Poultry and Wild Birds(WHO, 8/2/06)

  17. Countries with H5N1 in Wild Birds(OIE, 8/22/05) • Georgia • Germany • Greece • Hungary • Indonesia • Iran • Italy • Japan • Kazakhstan • Kuwait • Mongolia • Nigeria • Poland • Russia • Serbia and Montenegro • Slovakia • Slovenia • South Korea • Spain • Sweden • Switzerland • Thailand • Turkey • Ukraine • United Kingdom • Vietnam • Afghanistan • Austria • Azerbaijan • Bosnia and Herzegovina • Bulgaria • Cambodia • Cameroon • China • Cote d’ Ivoire • Croatia • Czech Republic • Denmark • Egypt • France

  18. Wild Bird Surveillance • Wildlife biologist monitor diseases of wild birds at the population level • Sick or Dead Wildlife website reporting • Bird Banding • Hunter Surveillance http://www.michigan.gov/dnr

  19. H5N1 Influenza in Humans-Risk • Transmission from birds to humans does not occur easily • Contact with feces or secretions from infected birds • Risk with butchering, preparing, defeathering of infected birds • NOT transmitted through cooked food

  20. Implications for Human Health • Asian Strain H5N1 in humans more aggressive than seasonal flu strains • Severe clinical course • Rapid deterioration • High fatality • Low transmissibility human-to-human • Incubation may be longer than seasonal influenza • Seasonal influenza: 2-3 days • H5N1: possibly up to 10 days • More studies needed

  21. Confirmed Human Cases of H5N1(WHO, 8/23/06)

  22. http://www.pandemicflu.gov/ (July 7, 2006)

  23. What is the H5N1 Pandemic Risk? • Three conditions must be met for a pandemic to start: • Emergence of a new influenza subtype • The strain infects humans causing serious illness • Spreads easily between humans • Each new H5N1 human case gives the virus a chance to mutate into a highly transmissible form, increasing the risk of a pandemic

  24. PANDEMIC

  25. MDCH Pandemic Influenza Plan 2005 • Revision of 2002 plan • Released November 2005 • Appendix to MDCH All-Hazards Response Plan • Pandemic plan updated as needed • www.michigan.gov/influenza

  26. Leads for Public Health • International: World Health Organization • United States: Centers for Disease Control and Prevention, DHHS • Michigan: Michigan Department of Community Health • County: Local Health Department/Jurisdiction

  27. Current WHO Risk Assessment

  28. 20th Century Influenza Pandemics • 1918 – 1919, “Spanish Flu” (H1N1) • Influenza A H1N1 viruses still circulate today • US mortality: approx. 500,000+ • 1957-58, “Asian Flu” (H2N2) • Identified in China (February 1957) with spread to US by June • US mortality: 69,800 • 1968-69, “Hong Kong Flu” (H3N2) • Influenza A H3N2 viruses still circulate today • First detected in Hong Kong (early 1968) and spread to US later that year • US mortality: 33,800

  29. Characteristic Moderate (1957 / ‘68-like) Severe (1918-like) Illness 3.4 million 3.4 million Outpatient 2.5 million 1.5 million Hospitalization 51,000 420,000 Deaths 15,000 125,000 Estimated Impact of a Future Pandemic in Michigan (*Michigan figures developed with Flu-Aid 2.0 software, CDC)

  30. MDCH Labs LHD’s/ MDSS Hospitals Non-MDCH Labs ER Syndromic Mi-FluFocus WHO Data Sentinel Physicians CDC Data Pharmacy OTC LHD’s/ Healthcare providers Influenza Surveillance • Michigan Disease Surveillance System • Sentinel Surveillance • Syndromic • Pharmacy • ER • Laboratory • National • International

  31. Treatment Options • Antiviral Medications • Neuraminidase Inhibitors • Oseltamivir • Zanamivir • Pandemic strain vaccine • Minimum 5 month production time • Need chicken eggs and viral seed stock Source: CDC

  32. Oseltamivir- Not a Panacea • Limited availability (one manufacturer) • Personal stockpiling could lead to: • Inappropriate use • Increased resistance by the virus (already one documented case) • Decreased availability for the critically ill • For prophylaxis, multiple courses may be needed throughout flu season

  33. Human Vaccine for Avian H5N1 • Effective vaccine is not yet available • Small batches of vaccine are undergoing clinical trials • Not ready for mass production • US has advance-ordered 20,000,000 doses • May not match strain that causes pandemic • Seasonal influenza vaccine does not protect against H5N1 strain

  34. Public Health:Non-Pharmaceutical Interventions • Social distancing • Schools • Business practices • Public gatherings • Respiratory/Cough Etiquette • Hand Hygiene

  35. Influenza Control Measures • Education to encourage prompt self-diagnosis • Hand hygiene • Consider masks, if possible, for symptomatic persons (then send them home!) • Cancellation of school/social gatherings • Quarantines

  36. Have a Plan! • Develop • Exercise • Update • Review • Exercise • Update…. CDC/EOC-PHIL

  37. Current U.S. Status • No current evidence in U.S. of highly pathogenic H5N1 in • Wild birds • Domestic poultry • Humans Images from: http://www.usda.gov/oc/photo

  38. Conclusion • Many unknowns • Simple precautions go a long way • Education is critical to your COOP • Get employees involved in the process

  39. Health AdviceGood Now, Good in a Pandemic • Get your annual flu shot • Won’t protect against a pandemic strain • Stay at home if you have a fever • Wash hands with soap or hand sanitizers when you sneeze or cough • Get adequate sleep, eat healthy, stay hydrated

  40. References • pandemicflu.gov • Michigan Department of Community Health (www.michigan.gov/flu) • www.who.int • www.cdc.gov • Local Health Department • Chamber of Commerce

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