Influenza overview: Difference between revisions
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==Overview== | === Overview === | ||
== Historical Perspective == | |||
== Classification == | |||
== Pathophysiology == | |||
== Causes == | |||
== Differentiating Influenza from other Diseases == | |||
== Epidemiology and Demographics == | |||
== Risk Factors == | |||
== Natural History, Complications and Prognosis == | |||
== Diagnosis == | |||
=== History and Symptoms === | |||
=== Physical Examination === | |||
=== Laboratory Findings === | |||
=== Chest X Ray === | |||
=== Other Diagnostic Studies === | |||
== Treatment == | |||
=== Medical Therapy === | |||
Primary Prevention | |||
Cost-Effectiveness of Therapy | |||
Future or Investigational Therapies | |||
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=== Overview === | |||
Influenza, commonly known as flu, is an [[infectious disease]] of birds and [[mammal]]s caused by [[RNA virus]]es of the biological family [[Orthomyxoviridae]] (the influenza viruses). In humans, common symptoms of influenza infection are [[fever]], [[pharyngitis|sore throat]], [[myalgia|muscle pains]], severe [[headache]], [[cough]]ing, [[fatigue (medical)|weakness]] and [[malaise|general discomfort]].<ref name=Merck>{{cite web |author= Merck Manual Home Edition |title=Influenza: Viral Infections |url= http://www.merck.com/mmhe/sec17/ch198/ch198c.html?}}</ref> In more serious cases, influenza [[sequela|causes]] [[pneumonia]], which can be fatal, particularly in young children and the elderly. Sometimes confused with the [[common cold]], influenza is a much more severe disease and is caused by a different type of virus.<ref name=Eccles>{{cite journal | last = Eccles | first = R | title = Understanding the symptoms of the common cold and influenza | journal = Lancet Infect Dis | volume = 5 | issue = 11 | pages = 718–25 | year = 2005 | id = PMID 16253889}}</ref> Although [[nausea]] and [[vomiting]] can be produced, especially in children,<ref name=Merck/> these symptoms are more characteristic of the unrelated [[gastroenteritis]], which is sometimes called "stomach flu" or "24-hour flu."<ref> [http://coldflu.about.com/od/flumisconceptions/f/stomachflu.htm Seasonal Flu vs. Stomach Flu] by Kristina Duda, R.N.; accessed March 12, 2007 (Website: "About, Inc., A part of The New York Times Company")</ref> | Influenza, commonly known as flu, is an [[infectious disease]] of birds and [[mammal]]s caused by [[RNA virus]]es of the biological family [[Orthomyxoviridae]] (the influenza viruses). In humans, common symptoms of influenza infection are [[fever]], [[pharyngitis|sore throat]], [[myalgia|muscle pains]], severe [[headache]], [[cough]]ing, [[fatigue (medical)|weakness]] and [[malaise|general discomfort]].<ref name=Merck>{{cite web |author= Merck Manual Home Edition |title=Influenza: Viral Infections |url= http://www.merck.com/mmhe/sec17/ch198/ch198c.html?}}</ref> In more serious cases, influenza [[sequela|causes]] [[pneumonia]], which can be fatal, particularly in young children and the elderly. Sometimes confused with the [[common cold]], influenza is a much more severe disease and is caused by a different type of virus.<ref name=Eccles>{{cite journal | last = Eccles | first = R | title = Understanding the symptoms of the common cold and influenza | journal = Lancet Infect Dis | volume = 5 | issue = 11 | pages = 718–25 | year = 2005 | id = PMID 16253889}}</ref> Although [[nausea]] and [[vomiting]] can be produced, especially in children,<ref name=Merck/> these symptoms are more characteristic of the unrelated [[gastroenteritis]], which is sometimes called "stomach flu" or "24-hour flu."<ref> [http://coldflu.about.com/od/flumisconceptions/f/stomachflu.htm Seasonal Flu vs. Stomach Flu] by Kristina Duda, R.N.; accessed March 12, 2007 (Website: "About, Inc., A part of The New York Times Company")</ref> | ||
Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating particulates/aerosols containing the virus, and from infected birds through their [[feces|droppings]]. Influenza can also be transmitted by [[saliva]], [[mucus|nasal secretions]], [[feces]] and [[blood]]. Infections also occur through contact with these body fluids or with contaminated surfaces. | Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating particulates/aerosols containing the virus, and from infected birds through their [[feces|droppings]]. Influenza can also be transmitted by [[saliva]], [[mucus|nasal secretions]], [[feces]] and [[blood]]. Infections also occur through contact with these body fluids or with contaminated surfaces. | ||
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[[Vaccination]]s against influenza are most commonly given to high-risk humans in industrialized countries<ref name=WHOvaccines>[http://www.who.int/wer/2005/wer8033.pdf WHO position paper: influenza vaccines] ''WHO weekly Epidemiological Record'' 19 August 2005, vol. 80, 33, pp. 277–288.</ref> and to farmed poultry.<ref>{{cite journal | last = Villegas | first = P | title = Viral diseases of the respiratory system | journal = Poult Sci | volume = 77 | issue = 8 | pages = 1143–5 | year = 1998 | id = PMID 9706079}}</ref> The most common human vaccine is the trivalent [[flu vaccine]] that contains purified and inactivated material from three viral strains. Typically this vaccine includes material from two [[influenzavirus A|influenza A virus]] subtypes and one [[Influenzavirus B|influenza B virus]] strain.<ref>{{cite journal | last = Horwood | first = F | coauthors = Macfarlane J | title = Pneumococcal and influenza vaccination: current situation and future prospects. | url= http://thorax.bmjjournals.com/cgi/reprint/57/suppl_2/ii24.pdf | journal = Thorax | volume = 57 Suppl 2 | issue = | pages = II24–II30 | year = | id = PMID 12364707}}</ref> A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time and different strains become dominant. [[Antiviral drug]]s can be used to treat influenza, with [[neuraminidase inhibitor]]s being particularly effective. | [[Vaccination]]s against influenza are most commonly given to high-risk humans in industrialized countries<ref name=WHOvaccines>[http://www.who.int/wer/2005/wer8033.pdf WHO position paper: influenza vaccines] ''WHO weekly Epidemiological Record'' 19 August 2005, vol. 80, 33, pp. 277–288.</ref> and to farmed poultry.<ref>{{cite journal | last = Villegas | first = P | title = Viral diseases of the respiratory system | journal = Poult Sci | volume = 77 | issue = 8 | pages = 1143–5 | year = 1998 | id = PMID 9706079}}</ref> The most common human vaccine is the trivalent [[flu vaccine]] that contains purified and inactivated material from three viral strains. Typically this vaccine includes material from two [[influenzavirus A|influenza A virus]] subtypes and one [[Influenzavirus B|influenza B virus]] strain.<ref>{{cite journal | last = Horwood | first = F | coauthors = Macfarlane J | title = Pneumococcal and influenza vaccination: current situation and future prospects. | url= http://thorax.bmjjournals.com/cgi/reprint/57/suppl_2/ii24.pdf | journal = Thorax | volume = 57 Suppl 2 | issue = | pages = II24–II30 | year = | id = PMID 12364707}}</ref> A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time and different strains become dominant. [[Antiviral drug]]s can be used to treat influenza, with [[neuraminidase inhibitor]]s being particularly effective. | ||
==Diagnosis== | === Diagnosis === | ||
===History and Symptoms=== | ==== History and Symptoms ==== | ||
In humans, influenza's effects are much more severe than those of the [[common cold]], and last longer. Recovery takes about one to two weeks. Influenza, however, can be deadly, especially for the weak, old or chronically ill. | In humans, influenza's effects are much more severe than those of the [[common cold]], and last longer. Recovery takes about one to two weeks. Influenza, however, can be deadly, especially for the weak, old or chronically ill. | ||
==Treatment== | === Treatment === | ||
===Future or Investigational Therapies=== | ==== Future or Investigational Therapies ==== | ||
Research on influenza includes studies on [[molecular virology]], how the virus produces disease ([[pathogenesis]]), host [[immune response]]s, [[genomics|viral genomics]], and how the virus spreads ([[epidemiology]]). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune response helps [[vaccine]] development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the [[Influenza Genome Sequencing Project]], which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect [[immunogenicity]], and how the virus [[evolution|evolves]] over time.<ref> [http://msc.tigr.org/infl_a_virus/index.shtml Influenza A Virus Genome Project] at The Institute of Genomic Research. Accessed 19 Oct 06</ref> | Research on influenza includes studies on [[molecular virology]], how the virus produces disease ([[pathogenesis]]), host [[immune response]]s, [[genomics|viral genomics]], and how the virus spreads ([[epidemiology]]). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune response helps [[vaccine]] development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the [[Influenza Genome Sequencing Project]], which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect [[immunogenicity]], and how the virus [[evolution|evolves]] over time.<ref> [http://msc.tigr.org/infl_a_virus/index.shtml Influenza A Virus Genome Project] at The Institute of Genomic Research. Accessed 19 Oct 06</ref> | ||
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The [[Influenza Genome Sequencing Project]] is creating a library of influenza sequences that will help us understand what makes one strain more lethal than another, what genetic determinants most affect [[immunogenicity]], and how the virus evolves over time. | The [[Influenza Genome Sequencing Project]] is creating a library of influenza sequences that will help us understand what makes one strain more lethal than another, what genetic determinants most affect [[immunogenicity]], and how the virus evolves over time. | ||
==References== | ---> | ||
=== References === | |||
{{Reflist|2}} | {{Reflist|2}} | ||
Revision as of 00:31, 25 October 2014
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Influenza from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Chest X Ray
Other Diagnostic Studies
Treatment
Medical Therapy
Primary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies