Influenza virus: Difference between revisions

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== Background ==
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==Background==
   
=== Microbiology ===
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===Microbiology===
   
* Enveloped, single-stranded, negative-sense RNA virus in the [[Family::Orthomyxoviridae]] family
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*Enveloped, single-stranded, negative-sense RNA virus in the [[Family::Orthomyxoviridae]] family
* Four genera corresponding to influenza A through D
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*Four genera corresponding to influenza A through D
* Typed by hemagglutinin (HA) and neuraminidase (NA) proteins
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*Typed by hemagglutinin (HA) and neuraminidase (NA) proteins
** Antigenic drift refers to small mutations
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**Antigenic drift refers to small mutations
** Antigenic shift refers to large changes from reassortment
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**Antigenic shift refers to large changes from reassortment
   
=== Epidemiology ===
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===Epidemiology===
   
* Worldwide
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*Worldwide
 
*Seasonal in temperate climates, lasting from fall through spring and peaking in late winter
 
*Antigenic drift usually results in local outbreaks, while antigenic shift can result in epidemic or pandemics
   
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== Clinical Manifestations ==
* Seasonal in temperate climates, lasting from fall through spring and peaking in late winter
 
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* Antigenic drift usually results in local outbreaks, while antigenic shift can result in epidemic or pandemics
 
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* Fever and respiratory symptoms, especially with myalgias
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== Management ==
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* Neuraminidase inhibitors started within 48 hours of symptom onset are associated with a shorter duration of illness
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** [[Oseltamivir]]
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** [[Zanamavir]]
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** [[Peramivir]] is IV only
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* Monitor for secondary bacterial pneumonia
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== Prevention ==
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* Annual influenza vaccination is recommended for everyone 6 months of age and older
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* Chemoprophylaxis with [[oseltamivir]] may be indicated as post-exposure prophylaxis or during local outbreaks for all people at risk
   
 
[[Category:RNA viruses]]
 
[[Category:RNA viruses]]

Latest revision as of 09:28, 18 August 2020

Background

Microbiology

  • Enveloped, single-stranded, negative-sense RNA virus in the Orthomyxoviridae family
  • Four genera corresponding to influenza A through D
  • Typed by hemagglutinin (HA) and neuraminidase (NA) proteins
    • Antigenic drift refers to small mutations
    • Antigenic shift refers to large changes from reassortment

Epidemiology

  • Worldwide
  • Seasonal in temperate climates, lasting from fall through spring and peaking in late winter
  • Antigenic drift usually results in local outbreaks, while antigenic shift can result in epidemic or pandemics

Clinical Manifestations

  • Fever and respiratory symptoms, especially with myalgias

Management

  • Neuraminidase inhibitors started within 48 hours of symptom onset are associated with a shorter duration of illness
  • Monitor for secondary bacterial pneumonia

Prevention

  • Annual influenza vaccination is recommended for everyone 6 months of age and older
  • Chemoprophylaxis with oseltamivir may be indicated as post-exposure prophylaxis or during local outbreaks for all people at risk