Respiratory - RespiratoryViruses An Overview...

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Respiratory Viruses An Overview
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Viruses Associated with  Respiratory Infections Syndrome Commonly Associated Viruses Less Commonly Associated Viruses Corza Rhinoviruses, Coronaviruses Influenza and parainfluenza viruses, enteroviruses, adenoviruses Influenza Influenza viruses Parainfluenza viruses, adenoviruses Croup Parainfluenza viruses Influenza virus, RSV, adenoviruses Bronchiolitis RSV Influenza and parainfluenza viruses, adenoviruses Bronchopneumonia Influenza virus, RSV, Adenoviruses Parainfluenza viruses, measles, VZV, CMV
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Influenza Virus RNA virus, genome consists of 8 segments enveloped virus, with haemagglutinin and neuraminidase spikes 3 types: A, B, and C Type A undergoes antigenic shift and drift. Type B undergoes antigenic drift only and type C is relatively stable (Courtesy of Linda Stannard, University of Cape Town, S.A.)
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Influenza A Virus Undergoes antigenic shifts and antigenic drifts with the haemagglutinin and neuraminidase proteins. Antigenic shifts of the haemagglutinin results in pandemics. Antigenic drifts in the H and N proteins result in epidemics. Usually causes a mild febrile illness. Death may result from complications such as viral/bacterial pneumonia.
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Epidemiology Pandemics - influenza A pandemics arise when a virus with a new haemagglutinin subtype emerges as a result of antigenic shift. As a result, the population has no immunity against the new strain. Antigenic shifts had occurred 3 times in the 20 th century. Epidemics - epidemics of influenza A and B arise through more minor antigenic drifts as a result of mutation.
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Past Antigenic Shifts 1918 H1N1 “Spanish Influenza” 20-40 million deaths 1957 H2N2 “Asian Flu” 1-2 million deaths 1968 H3N2 “Hong Kong Flu” 700,000 deaths 1977 H1N1 Re-emergence No pandemic 2009 H1N1 “Swine Flu Mild Pandemic At least 15 HA subtypes and 9 NA subtypes occur in nature. Up until 1997, only viruses of H1, H2, and H3 are known to infect and cause disease in humans.
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Avian Influenza H5N1 An outbreak of Avian Influenza H5N1 occurred in Hong Kong in 1997 where 18 persons were infected of which 6 died. The source of the virus was probably from infected chickens and the outbreak was eventually controlled by a mass slaughter of chickens in the territory.
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This note was uploaded on 12/27/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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Respiratory - RespiratoryViruses An Overview...

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