Pandemic Influenza

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Pandemic Influenza

• Susan Penfield, MD
• Infectious Disease Control Unit Manager
• Community Preparedness Section
• Texas Department of State Health Services
• June 20, 2006

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Influenza Pandemics

• Criteria for a pandemic influenza virus
• novel influenza A strain
• little or no immunity in population
• Easy person-to-person transmission with
  significant disease
• Occur at irregular intervals
• Other organisms besides flu virus could also
  cause a pandemic

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Influenza viruses

• Influenza B
• Humans only
• Severe disease usually limited to elderly and
  high risk
• No Pandemics

• Influenza A
• Humans, swine, horses, ducks, chickens, seals
  whales
• Can cause high mortality in young persons
• Can cause Pandemics

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Recorded Influenza Pandemics
1893
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Mechanisms of Antigenic Shift
Direct
16 HAs 9 NAs
Non-human virus
Human virus
Reassorted virus
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Pandemic Influenza
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Pandemic Influenza Percentage of Influenza
Deaths by Age Group, 1917-1918
Crosby. Influenza in America, 1977
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Human Deaths from H5N1 by age
25 were10 years old or under 69 were 25 years
old or under 90 were 35 years old or under Total
121
Source World Health Organization Chart created
by the Office of Public Health Emergency
Preparedness
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Phases of an Influenza Pandemic
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Countries with H5N1 Influenza in animals humans
Countries with H5N1 influenza in animals
Countries with H5N1 influenza in humans
51
18
11
10
5
2
2
1
2005
2006
2004
2003
Through June 15, 2006
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New Countries with H5N1 in birds
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Worst Case Scenario