Influenza: Difference between revisions
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[[Image:Influenza research.jpg|thumb|220px|right|CDC scientist working on influenza under high bio-safety conditions]] | [[Image:Influenza research.jpg|thumb|220px|right|CDC scientist working on influenza under high bio-safety conditions]] | ||
Revision as of 22:32, 9 January 2012
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Influenza Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Influenza On the Web |
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American Roentgen Ray Society Images of Influenza |
For patient information click here
| Influenza | |
 | |
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| TEM of negatively stained influenza virons, magnified approximately 70,000 times | |
| ICD-10 | J10, J11 |
| ICD-9 | 487 |
| DiseasesDB | 6791 |
| MedlinePlus | 000080 |
| MeSH | D007251 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Historical perspective
Classification
Diagnosis
History & Symptoms
Lab Tests
Epidemiology & Demographics
Primary Prevention
Medical Therapy
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.[1]
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.[2] New technologies are also being developed to grow virus in cell culture; which promises higher yields, less cost, better quality and surge capacity.[3] 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.[4] 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.
Infection in other animals
Influenza infects many animal species and transfer of viral strains between species can occur. Birds are thought to be the main animal reservoirs of influenza viruses.[5] Sixteen forms of hemagglutinin and 9 forms of neuraminidase have been identified. All known subtypes (HxNy) are found in birds but many subtypes are endemic in humans, dogs, horses, and pigs; populations of camels, ferrets, cats, seals, mink, and whales also show evidence of prior infection or exposure to influenza.[6] Variants of flu virus are sometimes named according to the species the strain is endemic in or adapted to. The main variants named using this convention are: Bird flu, Human Flu, Swine Flu, Horse Flu and Dog Flu. (Cat flu generally refers to Feline viral rhinotracheitis or Feline calicivirus and not infection from an influenza virus.) In pigs, horses and dogs, influenza symptoms are similar to humans, with cough, fever and loss of appetite.[6] The frequency of animal diseases are not as well-studied as human infection, but an outbreak of influenza in harbour seals caused approximately 500 seal deaths off the New England coast in 1979–1980.[7] On the other hand, outbreaks in pigs are common and do not cause severe mortality.[6]
Flu symptoms in birds are variable and can be unspecific.[8] The symptoms following infection with low-pathogenicity avian influenza may be as mild as ruffled feathers, a small reduction in egg production, or weight loss combined with minor respiratory disease.[9] Since these mild symptoms can make diagnosis in the field difficult, tracking the spread of avian influenza requires laboratory testing of samples from infected birds. Some strains such as Asian H9N2 are highly virulent to poultry, and may cause more extreme symptoms and significant mortality.[10] In its most highly pathogenic form, influenza in chickens and turkeys produces a sudden appearance of severe symptoms and almost 100% mortality within two days.[11] As the virus spreads rapidly in the crowded conditions seen in the intensive farming of chickens and turkeys, these outbreaks can cause large economic losses to poultry farmers.
An avian-adapted, highly pathogenic strain of H5N1 (called HPAI A(H5N1), for "highly pathogenic avian influenza virus of type A of subtype H5N1") causes H5N1 flu, commonly known as "avian influenza" or simply "bird flu", and is endemic in many bird populations, especially in Southeast Asia. This Asian lineage strain of HPAI A(H5N1) is spreading globally. It is epizootic (an epidemic in non-humans) and panzootic (a disease affecting animals of many species, especially over a wide area) killing tens of millions of birds and spurring the culling of hundreds of millions of other birds in an attempt to control its spread. Most references in the media to "bird flu" and most references to H5N1 are about this specific strain.[12][13]
At present, HPAI A(H5N1) is an avian disease and there is no evidence suggesting efficient human-to-human transmission of HPAI A(H5N1). In almost all cases, those infected have had extensive physical contact with infected birds.[14] In the future, H5N1 may mutate or reassort into a strain capable of efficient human-to-human transmission. Due to its high lethality and virulence, its endemic presence, and its large and increasing biological host reservoir, the H5N1 virus is the world's pandemic threat in the 2006–7 flu season, and billions of dollars are being raised and spent researching H5N1 and preparing for a potential influenza pandemic.[15]
Cost-Effectiveness of Therapy
See also
- Information concerning flu research can be found at
References and notes
- ↑ 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
- ↑ Gorman O, Bean W, Kawaoka Y, Webster R (1990). "Evolution of the nucleoprotein gene of influenza A virus". J Virol. 64 (4): 1487–97. PMID 2319644.
- ↑ 6.0 6.1 6.2
- ↑ Hinshaw V, Bean W, Webster R, Rehg J, Fiorelli P, Early G, Geraci J, St Aubin D (1984). "Are seals frequently infected with avian influenza viruses?". J Virol. 51 (3): 863–5. PMID 6471169.
- ↑ Elbers A, Koch G, Bouma A (2005). "Performance of clinical signs in poultry for the detection of outbreaks during the avian influenza A (H7N7) epidemic in The Netherlands in 2003". Avian Pathol. 34 (3): 181–7. PMID 16191700.
- ↑ Capua I, Mutinelli F. "Low pathogenicity (LPAI) and highly pathogenic (HPAI) avian influenza in turkeys and chicken." In: Capua I, Mutinelli F. (eds.), A Colour Atlas and Text on Avian Influenza, Papi Editore, Bologna, 2001, pp. 13–20
- ↑ Bano S, Naeem K, Malik S (2003). "Evaluation of pathogenic potential of avian influenza virus serotype H9N2 in chickens". Avian Dis. 47 (3 Suppl): 817–22. PMID 14575070.
- ↑ Swayne D, Suarez D (2000). "Highly pathogenic avian influenza". Rev Sci Tech. 19 (2): 463–82. PMID 10935274.
- ↑ Li K, Guan Y, Wang J, Smith G, Xu K, Duan L, Rahardjo A, Puthavathana P, Buranathai C, Nguyen T, Estoepangestie A, Chaisingh A, Auewarakul P, Long H, Hanh N, Webby R, Poon L, Chen H, Shortridge K, Yuen K, Webster R, Peiris J (2004). "Genesis of a highly pathogenic and potentially pandemic H5N1 influenza virus in eastern Asia". Nature. 430 (6996): 209–13. PMID 15241415.
- ↑ Li KS, Guan Y, Wang J, Smith GJ, Xu KM, Duan L, Rahardjo AP, Puthavathana P, Buranathai C, Nguyen TD, Estoepangestie AT, Chaisingh A, Auewarakul P, Long HT, Hanh NT, Webby RJ, Poon LL, Chen H, Shortridge KF, Yuen KY, Webster RG, Peiris JS. "The Threat of Pandemic Influenza: Are We Ready?" Workshop Summary The National Academies Press (2005) "Today's Pandemic Threat: Genesis of a Highly Pathogenic and Potentially Pandemic H5N1 Influenza Virus in Eastern Asia", pages 116–130
- ↑ Liu J (2006). "Avian influenza—a pandemic waiting to happen?" (PDF). J Microbiol Immunol Infect. 39 (1): 4–10. PMID 16440117.
- ↑ Rosenthal, E. and Bradsher, K. Is Business Ready for a Flu Pandemic? The New York Times 16-03-2006 Accessed 17-04-2006
Further reading
- NEJM's Avian Influenza
- Bernd Sebastian Kamps, Christian Hoffmann and Wolfgang Preiser (Eds.) Influenza Report 2006 Flying publisher 2006.
- Arnold J. Levine 'Viruses' Scientific American Library, WH Freeman, 1992 ISBN 0-7167-5031-7
- Samuel Baron et al. 'Medical Microbiology' Fourth Edition, The University of Texas Medical Branch at Galveston 1996 ISBN 0-9631172-1-1.
- Cox NJ, Subbarao K. 'Influenza.' Lancet. 1999 Oct 9;354(9186):1277–82. PMID 10520648
- Edwin D. Kilbourne Influenza Pandemics of the 20th Century Emerging Infectious Diseases Special Issue: Influenza Vol. 12, No. 1 January 2006
- Richard Collier 'The Plague of the Spanish Lady' Macmillan publishers (London) 1974 ISBN 0-7490-0246-8
- John M. Barry 'The Great Influenza: the Epic Story of the Deadliest Plague in History' Penguin 2004 ISBN 0-670-89473-7
- Webster RG, Bean WJ, Gorman OT, Chambers TM, Kawaoka Y. "Evolution and ecology of influenza A viruses." Microbiol Rev. 1992 Mar;56(1):152–79. PMID 1579108
- Scholtissek C. 'Molecular epidemiology of influenza.' Arch Virol Suppl. 1997;13:99–103. PMID 9413530
- Adolfo García-Sastre Antiviral Response in Pandemic Influenza Viruses 'Emerging Infectious Diseases Special Issue: Influenza Vol. 12, No. 1 January 2006
- Zambon MC. 'The pathogenesis of influenza in humans.' Rev Med Virol. 2001 Jul–Aug;11(4):227–41. PMID 11479929
- Walter R. Dowdle Influenza Pandemic Periodicity, Virus Recycling, and the Art of Risk Assessment 'Emerging Infectious Diseases Special Issue: Influenza Vol. 12, No. 1 January 2006
- Horimoto T, Kawaoka Y. Pandemic threat posed by avian influenza A viruses. Clin Microbiol Rev. 2001 Jan;14(1):129–49. PMID 11148006
- Epidemiology of WHO-confirmed human cases of avian influenza A(H5N1) infection
- CDC 2005. Centers for Disease Control. Prevention and Control of Influenza Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2005; 54 (RR08): 1–40.
- Arnold S. Monto Vaccines and Antiviral Drugs in Pandemic Preparedness Emerging Infectious Diseases Special Issue: Influenza Vol. 12, No. 1 January 2006
- Peter Palese Making Better Influenza Virus Vaccines? Emerging Infectious Diseases Special Issue: Influenza Vol. 12, No. 1 January 2006
- WHO (PDF} contains latest Evolutionary "Tree of Life" for H5N1 article Antigenic and genetic characteristics of H5N1 viruses and candidate H5N1 vaccine viruses developed for potential use as pre-pandemic vaccines published August 18, 2006
- WHO's assessment of Flu Research as of November 2006.
External links
- Info on influenza at CDC
- Fact Sheet Overview of influenza at World Health Organization
- Health encyclopedia entry at NHS Direct
- BioHealthBase Bioinformatics Resource Center Database of influenza sequences and related information.
- Overview of influenza at MedicineNet
- Congressional Research Service (CRS) Reports regarding Influenza Law related government reports at University of North Texas
- Influenza Surveillance and Contingency Plans (by Country/Region)
- Orthomyxoviridae The Universal Virus Database of the International Committee on Taxonomy of Viruses
- Influenza Virus Resource from the NCBI
- InfluenzaWorld Resource for all influenza-related information.
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Influenza Microchapters |
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Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Influenza On the Web |
|
American Roentgen Ray Society Images of Influenza |
Template:Respiratory pathology Template:Viral diseases Template:Link FA
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