Avian Influenza and the Threat of an Impending Pandemic

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Avian Influenza and the Threat of an Impending
Pandemic

• Eden V. Wells, MD, MPH
• Michigan Department of Community Health

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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
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As and Bs, Hs and Ns

• 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

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Influenza Virus Structure
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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

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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

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Seasonal Influenza

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

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Seasonal Effects
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Seasonal Influenza Surveillance
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Avian InfluenzaThe Bird Flu
Images from http//www.usda.gov/oc/photo
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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

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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 reportable disease in
  Michigan

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The Role of Animals in Influenza A Infection
Mammals
Domestic Birds
Shore Birds and Wild Waterfowl
Humans
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Countries with H5N1 in Poultry(OIE, 8/22/06)

• Hungary
• India
• Indonesia
• Iraq
• Israel
• Japan
• Jordan
• Kazakhstan
• Laos
• Malaysia
• Myanmar
• Niger
• Nigeria

• Afghanistan
• Albania
• Azerbaijan
• Burkina Faso
• Cameroon
• Cambodia
• China
• Cote d Ivoire
• Cyprus
• Denmark
• Dijbouti
• Egypt
• France
• Germany

• North Korea
• Pakistan
• Palestian Aut. Territories
• Romania
• Russia
• Serbia and Montenegro
• South Korea
• Sudan
• Sweden
• Thailand
• Turkey
• Ukraine
• Vietnam

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

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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
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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

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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

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Confirmed Human Cases of H5N1(WHO, 8/23/06)
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http//www.pandemicflu.gov/ (July 7, 2006)
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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

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PANDEMIC
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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

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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

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Current WHO Risk Assessment
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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

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Estimated Impact of a Future Pandemic in Michigan

(Michigan figures developed with Flu-Aid 2.0
software, CDC)
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Influenza Surveillance

• Michigan Disease Surveillance System
• Sentinel Surveillance
• Syndromic
• Pharmacy
• ER
• Laboratory
• National
• International

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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
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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

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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

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Public HealthNon-Pharmaceutical Interventions

• Social distancing
• Schools
• Business practices
• Public gatherings
• Respiratory/Cough Etiquette
• Hand Hygiene

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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

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Have a Plan!

• Develop
• Exercise
• Update
• Review
• Exercise
• Update.

CDC/EOC-PHIL
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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
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Conclusion

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

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Health AdviceGood Now, Good in a Pandemic

• Get your annual flu shot
• Wont 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

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References

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