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'''For patient information click [[{{PAGENAME}} (patient information)|here]]'''.
__NOTOC__
{{West nile virus infection}}


{{Taxobox
{{About0|West nile virus infection}}
| name = ''West Nile virus''
| image = NIAID-west-Nile.jpg
| virus_group = iv
| familia  = ''[[Flaviviridae]]''
| genus = ''[[Flavivirus]]''
| species = '''''West Nile virus'''''
}}
{{Infobox_Disease
| Name          = West Nile Fever
| DiseasesDB    = 30025
| ICD10          = {{ICD10|A|92|3}}
| MeshID        = D014901
}}


{{West nile virus}}
{{CMG}}
{{CMG}}


==[[West nile virus overview|Overview]]==
==Overview==
WNV is an enveloped positive-sense ssRNA virus of 11000 base pairs (bp) that is considered a member of the Japanese encephalitis serocomplex. It belongs to the genus Flavivirus and family Flaviviridae. Its RNA encodes structural and non-structural proteins. Although 7 lineages of WNV have been described, only lineage 1 and 2 are clinically significant. The viral natural reservoir includes many species, such as humans, horses, dogs, and cats; but the main natural reservoir is birds.


==[[West nile virus historical perspective|Historical Perspective]]==
==Taxonomy==
Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage; Flaviviridae; Flavivirus; Japanese encephalitis virus group<ref name=NCBI>{{cite web | title = West Nile Virus | url = http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=11082&lvl=3&lin=f&keep=1&srchmode=1&unlock }}</ref>


==[[West nile virus pathophysiology|Pathophysiology]]==
==Biology==


==[[West nile virus epidemiology and demographics|Epidemiology & Demographics]]==
{| style="float: right;"
| [[File:WNV2.jpg|200px|thumb|none| Presence of West Nile virus virions, in an isolate that was grown in a cell culture.<SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
|}
WNV is a member of Japanese encephalitis serocomplex and belongs to the [[genus]] [[Flavivirus]], family [[Flaviviridae]].  Other [[species]] of the this serocomplex include the [[St Louis encephalitis virus]] and the [[Japanese encephalitis virus]].<ref name="pmid23860989">{{cite journal| author=Petersen LR, Brault AC, Nasci RS| title=West Nile virus: review of the literature. | journal=JAMA | year= 2013 | volume= 310 | issue= 3 | pages= 308-15 | pmid=23860989 | doi=10.1001/jama.2013.8042 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23860989  }} </ref>


==[[West nile virus epidemiology and demographics|Risk Factors]]==
The WNV has an icosahedral symmetry, with a smooth surface.<ref name="Mukhopadhyay2003">{{cite journal|last1=Mukhopadhyay|first1=S.|title=Structure of West Nile Virus|journal=Science|volume=302|issue=5643|year=2003|pages=248–248|issn=0036-8075|doi=10.1126/science.1089316}}</ref>  It is an enveloped virus with a nucleocapsid core built of [[RNA]] and [[capsid]] proteins.  Its [[genome]] is contained in a single-stranded [[RNA]] of about 11000 bp.<ref name="CampbellMarfin2002">{{cite journal|last1=Campbell|first1=Grant L|last2=Marfin|first2=Anthony A|last3=Lanciotti|first3=Robert S|last4=Gubler|first4=Duane J|title=West Nile virus|journal=The Lancet Infectious Diseases|volume=2|issue=9|year=2002|pages=519–529|issn=14733099|doi=10.1016/S1473-3099(02)00368-7}}</ref>  It contains a single open reading frame ([[ORF]]), a 5' untranslated region ([[UTR]]), and another 3' region which is also not translated. The ORF contains a single polyprotein that produces 3 smaller types of structure proteins and 7 of non-structural proteins following processing and translation.
* Structural proteins are responsible for the formation of the viral particle and include:
:* Envelope proteins
:* Membrane proteins
:* C proteins
* Non-structural proteins are responsible for viral replication, evasion of the immune system, and assembly of virions. They include:
:*NS1
:*NS2A
:*NS2B
:*NS3
:*NS4A
:*NS4B
:*NS5


==[[West nile virus screening|Screening]]==
The WNV may be classified in 7 phylogenetic lineages.  Of these, only 1 and 2 have been identified as causative agents of disease in humans and are considered clinically significant.<ref name=CDC>{{cite web | title = West Nile Virus | url = http://wwwnc.cdc.gov/eid/article/10/1/pdfs/02-0616.pdf }}</ref><ref name="pmid12890319">{{cite journal| author=Miller DL, Mauel MJ, Baldwin C, Burtle G, Ingram D, Hines ME et al.| title=West Nile virus in farmed alligators. | journal=Emerg Infect Dis | year= 2003 | volume= 9 | issue= 7 | pages= 794-9 | pmid=12890319 | doi=10.3201/eid0907.030085 | pmc=PMC3023431 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12890319  }} </ref><ref name="pmid16704810">{{cite journal| author=Bakonyi T, Ivanics E, Erdélyi K, Ursu K, Ferenczi E, Weissenböck H et al.| title=Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe. | journal=Emerg Infect Dis | year= 2006 | volume= 12 | issue= 4 | pages= 618-23 | pmid=16704810 | doi=10.3201/eid1204.051379 | pmc=PMC3294705 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16704810  }} </ref><ref name="pmid14585341">{{cite journal| author=Charrel RN, Brault AC, Gallian P, Lemasson JJ, Murgue B, Murri S et al.| title=Evolutionary relationship between Old World West Nile virus strains. Evidence for viral gene flow between Africa, the Middle East, and Europe. | journal=Virology | year= 2003 | volume= 315 | issue= 2 | pages= 381-8 | pmid=14585341 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14585341  }} </ref><ref name="pmid12093177">{{cite journal| author=Lanciotti RS, Ebel GD, Deubel V, Kerst AJ, Murri S, Meyer R et al.| title=Complete genome sequences and phylogenetic analysis of West Nile virus strains isolated from the United States, Europe, and the Middle East. | journal=Virology | year= 2002 | volume= 298 | issue= 1 | pages= 96-105 | pmid=12093177 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12093177  }} </ref><ref name="pmid21781205">{{cite journal| author=Papa A, Xanthopoulou K, Gewehr S, Mourelatos S| title=Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece. | journal=Clin Microbiol Infect | year= 2011 | volume= 17 | issue= 8 | pages= 1176-80 | pmid=21781205 | doi=10.1111/j.1469-0691.2010.03438.x | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21781205  }} </ref><ref name="pmid22406344">{{cite journal| author=Savini G, Capelli G, Monaco F, Polci A, Russo F, Di Gennaro A et al.| title=Evidence of West Nile virus lineage 2 circulation in Northern Italy. | journal=Vet Microbiol | year= 2012 | volume= 158 | issue= 3-4 | pages= 267-73 | pmid=22406344 | doi=10.1016/j.vetmic.2012.02.018 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22406344  }} </ref><ref name="pmid21586266">{{cite journal| author=Valiakos G, Touloudi A, Iacovakis C, Athanasiou L, Birtsas P, Spyrou V et al.| title=Molecular detection and phylogenetic analysis of West Nile virus lineage 2 in sedentary wild birds (Eurasian magpie), Greece, 2010. | journal=Euro Surveill | year= 2011 | volume= 16 | issue= 18 | pages=  | pmid=21586266 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21586266  }} </ref>
* Lineage 1: Widespread, isolates from Europe, America, Middle East, India, Africa, and Australia
* Lingeage 2: Southern Africa, Madagascar, and Europe


==[[West nile virus causes|Causes]]==
==Natural reservoir==
Although WNV can infect humans and numerous animals, birds are its main [[natural reservoir]].<ref name="pmid23860989">{{cite journal| author=Petersen LR, Brault AC, Nasci RS| title=West Nile virus: review of the literature. | journal=JAMA | year= 2013 | volume= 310 | issue= 3 | pages= 308-15 | pmid=23860989 | doi=10.1001/jama.2013.8042 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23860989  }} </ref><ref name="CampbellMarfin2002">{{cite journal|last1=Campbell|first1=Grant L|last2=Marfin|first2=Anthony A|last3=Lanciotti|first3=Robert S|last4=Gubler|first4=Duane J|title=West Nile virus|journal=The Lancet Infectious Diseases|volume=2|issue=9|year=2002|pages=519–529|issn=14733099|doi=10.1016/S1473-3099(02)00368-7}}</ref>


==[[West nile virus differential diagnosis|Differentiating West nile virus from other Diseases]]==
==Gallery==


==[[West nile virus natural history|Natural History, Complications & Prognosis]]==
<gallery>


==Diagnosis==
Image: Flavivirus13.jpeg| West Nile virus is a flavivirus commonly found in Africa, West Asia, and the Middle East. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
[[West nile virus history and symptoms|History & Symptoms]] | [[West nile virus physical examination|Physical Examination]] | [[West nile virus staging|Staging]] | [[West nile virus laboratory tests|Lab Tests]] | [[West nile virus electrocardiogram|Electrocardiogram]] | [[West nile virus chest x ray|Chest X Ray]] | [[West nile virus CT|CT]] | [[West nile virus MRI|MRI]] | [[West nile virus echocardiography or ultrasound|Echocardiography or Ultrasound]] | [[West nile virus other imaging findings|Other Imaging Findings]] | [[West nile virus other diagnostic studies|Other Diagnostic Studies]]


==Treatment==
Image: Flavivirus12.jpeg| This is a transmission electron micrograph (TEM) of the West Nile virus (WNV). <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
[[West nile virus medical therapy|Medical Therapy]] | [[West nile virus surgery|Surgery]] | [[West nile virus primary prevention|Primary Prevention]] | [[West nile virus secondary prevention|Secondary Prevention]]


==Related Chapters==
Image: Flavivirus06.jpeg| Digitally-colorized transmission electron micrograph (TEM) of the West Nile virus (WNV). <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
*[[CCR5]]
</gallery>


==Resources==
==References==
 
{{Reflist|2}}
{{commons|West Nile virus}}
* U.S. [[Centers for Disease Control and Prevention]] (CDC) pages
** [http://www.cdc.gov/ncidod/dvbid/westnile/ West Nile virus] topic page
** [http://www.cdc.gov/ncidod/dvbid/westnile/map.htm World map of West Nile and related viruses]
** [http://www.cdc.gov/ncidod/dvbid/westnile/surv&controlCaseCount03.htm 2003 case count]
* U.S. [[National Institute for Occupational Safety and Health]] (NIOSH) pages
** [http://www.cdc.gov/niosh/docs/2005-155/ Recommendations for Protecting Outdoor Workers from West Nile Virus Exposure]
** [http://www.cdc.gov/niosh/docs/2006-115/ Recommendations for Protecting Laboratory, Field, and Clinical Workers from West Nile Virus Exposure]
* [http://www.vrc.nih.gov Vaccine Research Center (VRC)] - Information concerning WNV vaccine research studies
* [http://westnilemaps.usgs.gov/us_human.html US map of West Nile virus]
* [http://www.phac-aspc.gc.ca/wnv-vwn/index.html Canadian Case Surveillance]
* L. Peterson, M. Marphin. [http://www.cfe.cornell.edu/erap/WNV/WNVEducDocs/Petersen-Marfin2002.pdf "West Nile virus: A Primer for the Clinician"], ''Annals of Internal Medicine,'' Vol. 137 No. 3, August 2002.
* D. J. White, D. L. Morse (eds.). "West Nile virus: Detection, Surveillance, and Control", [http://www.annalsnyas.org/content/vol951/issue1/ ''Annals of the New York Academy of Sciences''], Vol. 951, 2001.
* [http://www.nature.com/nsu/021014/021014-5.html ''Nature'' news article on West Nile paralysis]
* [http://www.cbc.ca/news/background/westnile/ CBC News Coverage of West Nile in Canada]
* [http://www.cdc.gov/ncidod/eid/vol5no5/hubalek.htm West Nile Fever in Europe]
* [http://www.encephalitisglobal.com Encephalitis Global, Inc.]
* [http://www.uos.harvard.edu/ehs/pes_wnv.shtml Harvard University fact sheet on West Nile Virus]
*[http://www.latimes.com/news/local/la-me-westnile19aug19,0,2186893.story?coll=la-home-local West Nile Cases Drop as Immunities Emerge, Experts Say]
* Nash D, Mostashari FM, Fine A, et al. N Engl J Med. 2001 [[June 14]];344(24):1807-14 [http://www.ncbi.nlm.nih.gov.arugula.cc.columbia.edu:2048/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11407341&query_hl=1&itool=pubmed_docsum The outbreak of West Nile virus infection in the New York City Area in 1999]
 
[[zh-min-nan:Se Nî-lô-hô pēⁿ-to̍k]]
[[ca:Virus del Nil Occidental]]
[[de:West-Nil-Virus]]
[[es:Virus del Nilo Occidental]]
[[fr:Virus du Nil occidental]]
[[id:Virus West Nile]]
[[it:Virus del Nilo occidentale]]
[[he:קדחת הנילוס המערבי]]
[[lt:Nilo karštinė]]
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[[ja:ウエストナイル熱]]
[[pt:Nilo ocidental]]
[[zh:西尼羅河病毒]]
 
 
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Latest revision as of 14:24, 4 May 2016

West nile virus infection Microchapters

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This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see West nile virus infection.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

WNV is an enveloped positive-sense ssRNA virus of 11000 base pairs (bp) that is considered a member of the Japanese encephalitis serocomplex. It belongs to the genus Flavivirus and family Flaviviridae. Its RNA encodes structural and non-structural proteins. Although 7 lineages of WNV have been described, only lineage 1 and 2 are clinically significant. The viral natural reservoir includes many species, such as humans, horses, dogs, and cats; but the main natural reservoir is birds.

Taxonomy

Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage; Flaviviridae; Flavivirus; Japanese encephalitis virus group[1]

Biology

Presence of West Nile virus virions, in an isolate that was grown in a cell culture. Image provided by the CDC Centers for Disease Control and Prevention [2]

WNV is a member of Japanese encephalitis serocomplex and belongs to the genus Flavivirus, family Flaviviridae. Other species of the this serocomplex include the St Louis encephalitis virus and the Japanese encephalitis virus.[3]

The WNV has an icosahedral symmetry, with a smooth surface.[4] It is an enveloped virus with a nucleocapsid core built of RNA and capsid proteins. Its genome is contained in a single-stranded RNA of about 11000 bp.[5] It contains a single open reading frame (ORF), a 5' untranslated region (UTR), and another 3' region which is also not translated. The ORF contains a single polyprotein that produces 3 smaller types of structure proteins and 7 of non-structural proteins following processing and translation.

  • Structural proteins are responsible for the formation of the viral particle and include:
  • Envelope proteins
  • Membrane proteins
  • C proteins
  • Non-structural proteins are responsible for viral replication, evasion of the immune system, and assembly of virions. They include:
  • NS1
  • NS2A
  • NS2B
  • NS3
  • NS4A
  • NS4B
  • NS5

The WNV may be classified in 7 phylogenetic lineages. Of these, only 1 and 2 have been identified as causative agents of disease in humans and are considered clinically significant.[6][7][8][9][10][11][12][13]

  • Lineage 1: Widespread, isolates from Europe, America, Middle East, India, Africa, and Australia
  • Lingeage 2: Southern Africa, Madagascar, and Europe

Natural reservoir

Although WNV can infect humans and numerous animals, birds are its main natural reservoir.[3][5]

Gallery

References

  1. ↑ "West Nile Virus".
  2. ↑ "http://phil.cdc.gov/phil/details.asp". External link in |title= (help)
  3. ↑ 3.0 3.1 Petersen LR, Brault AC, Nasci RS (2013). "West Nile virus: review of the literature". JAMA. 310 (3): 308–15. doi:10.1001/jama.2013.8042. PMID 23860989.
  4. ↑ Mukhopadhyay, S. (2003). "Structure of West Nile Virus". Science. 302 (5643): 248–248. doi:10.1126/science.1089316. ISSN 0036-8075.
  5. ↑ 5.0 5.1 Campbell, Grant L; Marfin, Anthony A; Lanciotti, Robert S; Gubler, Duane J (2002). "West Nile virus". The Lancet Infectious Diseases. 2 (9): 519–529. doi:10.1016/S1473-3099(02)00368-7. ISSN 1473-3099.
  6. ↑ "West Nile Virus" (PDF).
  7. ↑ Miller DL, Mauel MJ, Baldwin C, Burtle G, Ingram D, Hines ME; et al. (2003). "West Nile virus in farmed alligators". Emerg Infect Dis. 9 (7): 794–9. doi:10.3201/eid0907.030085. PMC 3023431. PMID 12890319.
  8. ↑ Bakonyi T, Ivanics E, Erdélyi K, Ursu K, Ferenczi E, Weissenböck H; et al. (2006). "Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe". Emerg Infect Dis. 12 (4): 618–23. doi:10.3201/eid1204.051379. PMC 3294705. PMID 16704810.
  9. ↑ Charrel RN, Brault AC, Gallian P, Lemasson JJ, Murgue B, Murri S; et al. (2003). "Evolutionary relationship between Old World West Nile virus strains. Evidence for viral gene flow between Africa, the Middle East, and Europe". Virology. 315 (2): 381–8. PMID 14585341.
  10. ↑ Lanciotti RS, Ebel GD, Deubel V, Kerst AJ, Murri S, Meyer R; et al. (2002). "Complete genome sequences and phylogenetic analysis of West Nile virus strains isolated from the United States, Europe, and the Middle East". Virology. 298 (1): 96–105. PMID 12093177.
  11. ↑ Papa A, Xanthopoulou K, Gewehr S, Mourelatos S (2011). "Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece". Clin Microbiol Infect. 17 (8): 1176–80. doi:10.1111/j.1469-0691.2010.03438.x. PMID 21781205.
  12. ↑ Savini G, Capelli G, Monaco F, Polci A, Russo F, Di Gennaro A; et al. (2012). "Evidence of West Nile virus lineage 2 circulation in Northern Italy". Vet Microbiol. 158 (3–4): 267–73. doi:10.1016/j.vetmic.2012.02.018. PMID 22406344.
  13. ↑ Valiakos G, Touloudi A, Iacovakis C, Athanasiou L, Birtsas P, Spyrou V; et al. (2011). "Molecular detection and phylogenetic analysis of West Nile virus lineage 2 in sedentary wild birds (Eurasian magpie), Greece, 2010". Euro Surveill. 16 (18). PMID 21586266.
  14. ↑ 14.0 14.1 14.2 "Public Health Image Library (PHIL)".
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