Influenza overview: Difference between revisions
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===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== | |||
===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 into new vaccines is particularly important: as current vaccines are slow and expensive to produce and must be reformulated every year. The sequencing of the influenza genome and [[recombinant DNA]] technology may accelerate the generation of new vaccine strains by allowing scientists to substitute new antigens into a previously-developed vaccine strain.<ref>{{cite journal | author = Subbarao K, Katz J | title = Influenza vaccines generated by reverse genetics. | journal = Curr Top Microbiol Immunol | volume = 283 | issue = | pages = 313-42 | year = | id = PMID 15298174}}</ref> New technologies are also being developed to grow virus in [[cell culture]]; which promises higher yields, less cost, better quality and surge capacity.<ref>{{cite journal | author = Bardiya N, Bae J | title = Influenza vaccines: recent advances in production technologies. | url=http://www.springerlink.com/content/jdt26gc39v4bwk9q/ | journal = Appl Microbiol Biotechnol | volume = 67 | issue = 3 | pages = 299–305 | year = 2005 | id = PMID 15660212}}</ref> The U.S. government has purchased from [[Sanofi Pasteur]] and [[Chiron Corporation]] several million doses of vaccine meant to be used in case of an [[influenza pandemic]] of [[H5N1]] avian influenza and is conducting clinical trials with these vaccines.<ref> [http://www.nytimes.com/2006/03/30/health/30vaccine.html?_r=1&oref=slogin New York Times article ""Doubt Cast on Stockpile of a Vaccine for Bird Flu""] by Denise Grady. Published: March 30, 2006. Accessed 19 Oct 06</ref> The UK government is also stockpiling millions of antiviral drugs(tamiflu, oseltamivir, zanimivir) to give to its citizens in the event of an outbreak, the UK [[Health Protection Agency]] has also gathered a limited amount of HPAI H5N1 vaccines for experimental purposes. | |||
'''Influenza research''' involves investigating [[molecular virology]], [[pathogenesis]], host [[immune response]]s, [[genomics]], and [[epidemiology]] regarding [[influenza]]. The main goal of research is to develop influenza countermeasures such as [[vaccine]]s, therapies and diagnostic tools. | |||
The potential [[H5N1]] pandemic has motivated a huge increase in flu research. At least 12 companies and 17 governments are developing pre-pandemic [[influenza vaccine]]s in 28 different clinical trials that, if successful, could turn a deadly pandemic infection into a nondeadly pandemic infection. A vaccine that could prevent any illness at all from the not-yet-existing pandemic influenza strain will take at least three months from the virus's emergence until full-scale vaccine production could begin; with vaccine production hoped to increase until one billion doses are produced by one year after the virus is first identified.<ref> [http://www.scidev.net/gateways/index.cfm?fuseaction=readitem&rgwid=2&item=Features&itemid=515&language=1 Science and Development Network] article ''Pandemic flu: fighting an enemy that is yet to exist'' published May 3, 2006.</ref> | |||
Improved influenza countermeasures require basic research on how viruses enter cells, replicate, mutate, evolve into new strains and induce an immune response. Solutions to limitations in current vaccine methods are being researched. | |||
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== | ||
Revision as of 19:59, 28 May 2013
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Influenza Microchapters |
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Treatment |
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Case Studies |
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Influenza overview On the Web |
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American Roentgen Ray Society Images of Influenza overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the biological family Orthomyxoviridae (the influenza viruses). In humans, common symptoms of influenza infection are fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.[1] In more serious cases, influenza 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.[2] Although nausea and vomiting can be produced, especially in children,[1] these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu."[3] 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 droppings. Influenza can also be transmitted by saliva, nasal secretions, feces and blood. Infections also occur through contact with these body fluids or with contaminated surfaces. Flu viruses can remain infectious for about one week at human body temperature, over 30 days at 0 °C (32 °F), and indefinitely at very low temperatures (such as lakes in northeast Siberia). Most influenza strains can be inactivated easily by disinfectants and detergents.[4][5][6] Flu spreads around the world in seasonal epidemics, killing millions of people in pandemic years and hundreds of thousands in non-pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains result from the spread of an existing flu virus to humans from other animal species. Since it first killed humans in Asia in the 1990s, a deadly avian strain named H5N1 has posed the greatest risk for a new influenza pandemic; fortunately, this virus has not mutated to a form that spreads easily between people.[7]
Vaccinations against influenza are most commonly given to high-risk humans in industrialized countries[8] and to farmed poultry.[9] 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 influenza A virus subtypes and one influenza B virus strain.[10] 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 drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.
Diagnosis
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.
Treatment
Future or Investigational Therapies
Research on influenza includes studies on molecular virology, how the virus produces disease (pathogenesis), host immune responses, 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 evolves over time.[11]
Research into new vaccines is particularly important: as current vaccines are slow and expensive to produce and must be reformulated every year. The sequencing of the influenza genome and recombinant DNA technology may accelerate the generation of new vaccine strains by allowing scientists to substitute new antigens into a previously-developed vaccine strain.[12] New technologies are also being developed to grow virus in cell culture; which promises higher yields, less cost, better quality and surge capacity.[13] The U.S. government has purchased from Sanofi Pasteur and Chiron Corporation several million doses of vaccine meant to be used in case of an influenza pandemic of H5N1 avian influenza and is conducting clinical trials with these vaccines.[14] The UK government is also stockpiling millions of antiviral drugs(tamiflu, oseltamivir, zanimivir) to give to its citizens in the event of an outbreak, the UK Health Protection Agency has also gathered a limited amount of HPAI H5N1 vaccines for experimental purposes.
Influenza research involves investigating molecular virology, pathogenesis, host immune responses, genomics, and epidemiology regarding influenza. The main goal of research is to develop influenza countermeasures such as vaccines, therapies and diagnostic tools.
The potential H5N1 pandemic has motivated a huge increase in flu research. At least 12 companies and 17 governments are developing pre-pandemic influenza vaccines in 28 different clinical trials that, if successful, could turn a deadly pandemic infection into a nondeadly pandemic infection. A vaccine that could prevent any illness at all from the not-yet-existing pandemic influenza strain will take at least three months from the virus's emergence until full-scale vaccine production could begin; with vaccine production hoped to increase until one billion doses are produced by one year after the virus is first identified.[15]
Improved influenza countermeasures require basic research on how viruses enter cells, replicate, mutate, evolve into new strains and induce an immune response. Solutions to limitations in current vaccine methods are being researched.
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
- ↑ 1.0 1.1 Merck Manual Home Edition. "Influenza: Viral Infections".
- ↑ Eccles, R (2005). "Understanding the symptoms of the common cold and influenza". Lancet Infect Dis. 5 (11): 718–25. PMID 16253889.
- ↑ 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")
- ↑ Suarez, D (2003). "The effect of various disinfectants on detection of avian influenza virus by real time RT-PCR". Avian Dis. 47 (3 Suppl): 1091–5. PMID 14575118. Unknown parameter
|coauthors=ignored (help) - ↑ Avian Influenza (Bird Flu): Implications for Human Disease. Physical characteristics of influenza A viruses. UMN CIDRAP.
- ↑ Flu viruses 'can live for decades' on ice, NZ Herald, November 30, 2006.
- ↑ "Avian influenza ("bird flu") fact sheet". WHO. February 2006. Retrieved 2006-10-20.
- ↑ WHO position paper: influenza vaccines WHO weekly Epidemiological Record 19 August 2005, vol. 80, 33, pp. 277–288.
- ↑ Villegas, P (1998). "Viral diseases of the respiratory system". Poult Sci. 77 (8): 1143–5. PMID 9706079.
- ↑ Horwood, F. "Pneumococcal and influenza vaccination: current situation and future prospects" (PDF). Thorax. 57 Suppl 2: II24–II30. PMID 12364707. Unknown parameter
|coauthors=ignored (help) - ↑ Influenza A Virus Genome Project at The Institute of Genomic Research. Accessed 19 Oct 06
- ↑ Subbarao K, Katz J. "Influenza vaccines generated by reverse genetics". Curr Top Microbiol Immunol. 283: 313–42. PMID 15298174.
- ↑ Bardiya N, Bae J (2005). "Influenza vaccines: recent advances in production technologies". Appl Microbiol Biotechnol. 67 (3): 299–305. PMID 15660212.
- ↑ New York Times article ""Doubt Cast on Stockpile of a Vaccine for Bird Flu"" by Denise Grady. Published: March 30, 2006. Accessed 19 Oct 06
- ↑ Science and Development Network article Pandemic flu: fighting an enemy that is yet to exist published May 3, 2006.