14_Infectiousdiseases

14_Infectiousdiseases - 1/9/2008 Lecture # 14 : Influenza...

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1/9/2008 1 Lecture # 14 : Influenza Pandemics of the 20 th Century and implications for Avian Flu Lecture Information Courtesy of 1) David K. Shay Influenza Branch Centers for Disease Control and Prevention, 2) Healthpolitics.com (Dr. M. McGee, 3) NYTimes Feb 19‟05-12 AND 4) BEST: 4) Rashid A. Chotani, MD, MPH Global Infectious Disease Surveillance & Alert System, Johns Hopkins Bloomberg School of Public Health Geography 1000 Spring 2008 Terms of Wisdom and Growth • Avian flu virus (H5N1) p.385-386 • What and where is CDC p. 387 • Life expectancy in 1955 and 2007 p. 387 • “Cultural Hazards” of mortality (US top 3) p. 388 • Infectious and Parasitic Diseases and share of global mortality p. 389 • AIDS, TB, and Malaria (effect, vectors of each, and yearly deaths) p. 389 • 2006 “Roll Back malaria” campaign and WHO efforts p. 399 • Globalization and Disease essay p. 400 Definitions Epidemic – a located cluster of cases Pandemic – worldwide epidemic Antigenic drift Changes in proteins by genetic point mutation & selection Ongoing and basis for change in vaccine each year Antigenic shift Changes in proteins through genetic reassortment Produces different viruses not covered by annual vaccine
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1/9/2008 2 3 types of the influenza virus: A, B and C reflect differences in the M protein on the envelope that contains the virus ‘A’ influenza viruses cause human and bird flu outbreaks – contain 8-segment RNA strand – segments break apart during replication to mix and reassort – potential for constant evolution is built in – sub-typed based on activity in envelope‟s glycoproteins: 1] hemagglutinin activity (H): 16 known varieties 2] neuraminidase activity (N): 9 known varieties Shorthand names have an “H” and “N” number (H1N1) Understanding Bird Flu and the Influenza Virus Influenza Virus Three types Surface antigens Influenza A subtypes Source: L. Stammard, 1995 Influenza Virion
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1/9/2008 3 Influenza: Epidemics and Pandemics Influenza is an annual cause of significant morbidity and mortality: epidemics recognized in temperate areas for many years Unpredictably and at irregular intervals, pandemics associated with increased mortality occur Attack rates approach 40-50% in some populations Criteria for a pandemic influenza virus: novel influenza A strain little or no immunity in population person-to-person transmission with disease H1 N1 H2 N2 H3 N3 H4 N4 H5 N5 H6 N6 H7 N7 H8 N8 H9 N9 H10 H11 H12 H13 H14 H15 Natural hosts of influenza viruses Haemagglutinin subtype Neuraminidase subtype Antigenic Change Antigenic „drift‟ occurs in HA and NA Associated with seasonal epidemics Continual development of new strains secondary to genetic mutations A viruses >> B viruses Antigenic „shift‟ occurs in HA and NA Associated with pandemics Appearance of novel influenza A viruses bearing new HA or HA & NA
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This note was uploaded on 04/06/2008 for the course GEOG 1000 taught by Professor Veeck during the Spring '08 term at Western Michigan.

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14_Infectiousdiseases - 1/9/2008 Lecture # 14 : Influenza...

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