West nile virus epidemiology and demographics: Difference between revisions

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{{West nile virus}}
{{West nile virus}}
{{CMG}}
{{CMG}}; {{AE}} {{JS}}; {{MJM}}
{{MJM}}
==Overview==
==Overview==
WNV is considered a worldwide infective agent. Since most cases are [[asymptomatic]] and self-limited, the true [[incidence]] and [[prevalence]] of West Nile virus fever are often underestimated. Between the years 1999 and 2013, a total of 39557 cases were reported by the [[CDC]] in USA alone. The 2002 outbreak in USA marks the WNV outbreak with the most recorded rates of neuroinvasive disease. Nonetheless, only 1/140 to 1/256 cases of West Nile fever are complicated by [[encephalitis]] or [[meningitis]]. WNV [[infection]] occurs predominantly during the end of summer and beginning of fall. Females are more likely to develop WNV infection. The prevalence of the disease is not affected by ethnicity or age, but elderly patients are more likely to experience a complicated clinical course.


==Incidence and Prevalence==
==Incidence and Prevalence==
West Nile virus is widely distributed across Australia, Middle East, Western Russia, Southwestern Asia, Africa and Southern Europe. Since 1999, a series of outbreaks, with virus likely of African origin, have increased the incidence of the disease across the previous countries.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref>
WNV is widely distributed across Australia, Middle East, Western Russia, Southwestern Asia, Africa and Southern Europe. A series of outbreaks in the Mediterranean basin between 1950 and 1960 and in Europe and Africa between 1970 and 1980, marking a continuously waxing and waning incidence during the second half of the 20th century.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref> In America, the virus was first isolated in 1999 in New York City. The WNV disseminated rapidly across the American continent to the West coast in just 4 years and to Argentina in 6 years.<ref name="pmid20360671">{{cite journal| author=Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC)| title=Surveillance for human West Nile virus disease - United States, 1999-2008. | journal=MMWR Surveill Summ | year= 2010 | volume= 59 | issue= 2 | pages= 1-17 | pmid=20360671 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20360671  }} </ref><ref name="pmid19145778">{{cite journal| author=Petersen LR, Hayes EB| title=West Nile virus in the Americas. | journal=Med Clin North Am | year= 2008 | volume= 92 | issue= 6 | pages= 1307-22, ix | pmid=19145778 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19145778  }} </ref> The 2002 outbreak in USA marked the highest rate of neuroinvasive disease of a single WNV outbreak. The total number of infected patients reached 4156, with 2942 (71%) of those suffering severe neuroinvasive disease.<ref name="pmid15018774">{{cite journal| author=O'Leary DR, Marfin AA, Montgomery SP, Kipp AM, Lehman JA, Biggerstaff BJ et al.| title=The epidemic of West Nile virus in the United States, 2002. | journal=Vector Borne Zoonotic Dis | year= 2004 | volume= 4 | issue= 1 | pages= 61-70 | pmid=15018774 | doi=10.1089/153036604773083004 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15018774  }} </ref>


Across the western hemisphere, the virus was discovered in 1999 in new York City.  The WNV was then spread across the continent, to the East cost of the US, in 4 years, and to Argentina in 6 years.<ref name="pmid20360671">{{cite journal| author=Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC)| title=Surveillance for human West Nile virus disease - United States, 1999-2008. | journal=MMWR Surveill Summ | year= 2010 | volume= 59 | issue= 2 | pages= 1-17 | pmid=20360671 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20360671  }} </ref><ref name="pmid19145778">{{cite journal| author=Petersen LR, Hayes EB| title=West Nile virus in the Americas. | journal=Med Clin North Am | year= 2008 | volume= 92 | issue= 6 | pages= 1307-22, ix | pmid=19145778 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19145778  }} </ref>
Most patients with WNV infection are [[asymptomatic]]. Accordingly, West Nile fever is considered to be underreported, either because infected patients do not seek medical attention or because they are not tested for the virus.<ref name="pmid19145778">{{cite journal| author=Petersen LR, Hayes EB| title=West Nile virus in the Americas. | journal=Med Clin North Am | year= 2008 | volume= 92 | issue= 6 | pages= 1307-22, ix | pmid=19145778 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19145778  }} </ref> Between 1999 and 2013, a total 39557 probable and confirmed cases of West Nile fever were reported to the [[CDC]] from across the US.<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="pmid20360671">{{cite journal| author=Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC)| title=Surveillance for human West Nile virus disease - United States, 1999-2008. | journal=MMWR Surveill Summ | year= 2010 | volume= 59 | issue= 2 | pages= 1-17 | pmid=20360671 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20360671  }} </ref> The [[outbreak]] of 2012, in which 2873 cases of neuroinvasive disease were reported, occurred during a period of increased mosquito [[infection]] rate. A possible explanation for this was the severe precipitation felt during the previous winter.<ref name="ChungBuseman2013">{{cite journal|last1=Chung|first1=Wendy M.|last2=Buseman|first2=Christen M.|last3=Joyner|first3=Sibeso N.|last4=Hughes|first4=Sonya M.|last5=Fomby|first5=Thomas B.|last6=Luby|first6=James P.|last7=Haley|first7=Robert W.|title=The 2012 West Nile Encephalitis Epidemic in Dallas, Texas|journal=JAMA|volume=310|issue=3|year=2013|pages=297|issn=0098-7484|doi=10.1001/jama.2013.8267}}</ref><ref name="GoodmanLivingston2012">{{cite journal|last1=Goodman|first1=Denise M.|last2=Livingston|first2=Edward H.|title=West Nile Virus|journal=JAMA|volume=308|issue=10|year=2012|pages=1052|issn=0098-7484|doi=10.1001/2012.jama.11678}}</ref>
 
Due to the fact that most cases of infection with the WNV are [[asymptomatic]]. West Nile fever is underreported, either because infected persons do not seek medical attention, or because they are not tested for the virus.<ref name="pmid19145778">{{cite journal| author=Petersen LR, Hayes EB| title=West Nile virus in the Americas. | journal=Med Clin North Am | year= 2008 | volume= 92 | issue= 6 | pages= 1307-22, ix | pmid=19145778 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19145778  }} </ref> Between 1999 and 2013, 39 557 probable and confirmed cases of West Nile fever were reported to the CDC, from across the US.<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="pmid20360671">{{cite journal| author=Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC)| title=Surveillance for human West Nile virus disease - United States, 1999-2008. | journal=MMWR Surveill Summ | year= 2010 | volume= 59 | issue= 2 | pages= 1-17 | pmid=20360671 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20360671  }} </ref>
 
The outbreak of 2012, in which 2873 cases of neuroinvasive disease were reported, occurred during a period of increased mosquito infection rate. A possible explanation for this was the severe precipitation felt during the previous winter.<ref name="ChungBuseman2013">{{cite journal|last1=Chung|first1=Wendy M.|last2=Buseman|first2=Christen M.|last3=Joyner|first3=Sibeso N.|last4=Hughes|first4=Sonya M.|last5=Fomby|first5=Thomas B.|last6=Luby|first6=James P.|last7=Haley|first7=Robert W.|title=The 2012 West Nile Encephalitis Epidemic in Dallas, Texas|journal=JAMA|volume=310|issue=3|year=2013|pages=297|issn=0098-7484|doi=10.1001/jama.2013.8267}}</ref><ref name="GoodmanLivingston2012">{{cite journal|last1=Goodman|first1=Denise M.|last2=Livingston|first2=Edward H.|title=West Nile Virus|journal=JAMA|volume=308|issue=10|year=2012|pages=1052|issn=0098-7484|doi=10.1001/2012.jama.11678}}</ref>


[[Image:WNV cumulative human disease cases.png|thumb|center|500 px|USA cumulative human disease cases of WNV in 2014. ''Data as of September 2014''<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention(CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]
[[Image:WNV cumulative human disease cases.png|thumb|center|500 px|USA cumulative human disease cases of WNV in 2014. ''Data as of September 2014''<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention(CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]
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==Age==
==Age==
Age has not been noted to influence the development of West Nile fever following [[infection]] with the WNV. However, elderly patients have an higher risk of developing severe forms of the disease.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref><ref name="pmid20874087">{{cite journal| author=Zou S, Foster GA, Dodd RY, Petersen LR, Stramer SL| title=West Nile fever characteristics among viremic persons identified through blood donor screening. | journal=J Infect Dis | year= 2010 | volume= 202 | issue= 9 | pages= 1354-61 | pmid=20874087 | doi=10.1086/656602 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20874087  }} </ref>
*The prevalence of WNV does not change with age.
*Elderly patients have a higher risk of developing severe forms of the disease.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref><ref name="pmid20874087">{{cite journal| author=Zou S, Foster GA, Dodd RY, Petersen LR, Stramer SL| title=West Nile fever characteristics among viremic persons identified through blood donor screening. | journal=J Infect Dis | year= 2010 | volume= 202 | issue= 9 | pages= 1354-61 | pmid=20874087 | doi=10.1086/656602 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20874087  }} </ref>


==Gender==
==Gender==
The female gender is more prone to develop West Nile fever following infection with the WNV.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref><ref name="pmid20874087">{{cite journal| author=Zou S, Foster GA, Dodd RY, Petersen LR, Stramer SL| title=West Nile fever characteristics among viremic persons identified through blood donor screening. | journal=J Infect Dis | year= 2010 | volume= 202 | issue= 9 | pages= 1354-61 | pmid=20874087 | doi=10.1086/656602 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20874087  }} </ref>
WNV is more prevalent in women.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref><ref name="pmid20874087">{{cite journal| author=Zou S, Foster GA, Dodd RY, Petersen LR, Stramer SL| title=West Nile fever characteristics among viremic persons identified through blood donor screening. | journal=J Infect Dis | year= 2010 | volume= 202 | issue= 9 | pages= 1354-61 | pmid=20874087 | doi=10.1086/656602 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20874087  }} </ref>
 
==Race==
The prevalence of WNV does not vary by race or ethnicity.


==Season==
==Season==
<!--Human illnesses usually peak in late summer or early fall (figure 2) [4]. As an example, cases peaked in late August during the 2012 outbreak in Dallas county, with 92 percent having illness onset during July through September [25]. The seasonal variation is because mosquitoes emerge in the spring in temperate climates, which begins viral amplification in the bird-mosquito-bird cycle. Viral amplification peaks in early fall; the risk of infection then decreases in humans when female mosquitoes begin diapause and infrequently bite. However, sporadic cases can occur throughout the year in southern states.
Infection with WNV commonly occurs during warmer seasons, such as the period between late summer and beginning of fall.<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>
 
-->


==Geographical Distribution==
==Geographical Distribution==
===US Disease Cases by State 2014===
WNV is considered a global virus. Outbreaks of the virus have been documented since its initial isolation in 1937 in approximately all regions of the world.
[[Image:West Nile Virus Disease Cases.png|thumb|center|1000 px| US West Nile Virus Disease Cases<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention(CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]


===West Nile Virus by State 2014===
===US disease sases by state - 2014===
[[Image:West Nile Virus Activity by State.png|thumb|center|1000 px| US West Nile Virus Disease Cases<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention(CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]
[[Image:West Nile Virus Disease Cases.png|thumb|center|1000 px| US West Nile Virus Disease Cases<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention( CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]


==Neuroinvasive Disease Incidence by State 2014==
===West Nile virus by state - 2014===
Due to the fact that infection with the WNV is often asymptomatic, the best approach to monitor incidence trends of the disease caused by the virus is by assessing the incidence of neuroinvasive disease, since its reporting is often adequate.<ref name="MayDavis2010">{{cite journal|last1=May|first1=F. J.|last2=Davis|first2=C. T.|last3=Tesh|first3=R. B.|last4=Barrett|first4=A. D. T.|title=Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas|journal=Journal of Virology|volume=85|issue=6|year=2010|pages=2964–2974|issn=0022-538X|doi=10.1128/JVI.01963-10}}</ref> Despite this, during an outbreak, only 40% of the cases who presented with compatible meningitis or encephalitis were tested for infection with the virus.<ref name="pmid22123531">{{cite journal| author=Weber IB, Lindsey NP, Bunko-Patterson AM, Briggs G, Wadleigh TJ, Sylvester TL et al.| title=Completeness of West Nile virus testing in patients with meningitis and encephalitis during an outbreak in Arizona, USA. | journal=Epidemiol Infect | year= 2012 | volume= 140 | issue= 9 | pages= 1632-6 | pmid=22123531 | doi=10.1017/S0950268811002494 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22123531 }} </ref>  Between 1999 and 2012, 16 196 cases of neuroinvasive disease by WNV, and 1549 fatalities were reported in the United Stated. The largest outbreaks of neuroinvasive disease were reported in 2002, with 2946 cases, in 2003, with 2866, and 2012, with 2873 cases.<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>  Although the number varies every year, some areas of the US are more affected by this form of the disease, particularly Midwest states.<ref name="pmid20360671">{{cite journal| author=Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC)| title=Surveillance for human West Nile virus disease - United States, 1999-2008. | journal=MMWR Surveill Summ | year= 2010 | volume= 59 | issue= 2 | pages= 1-17 | pmid=20360671 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20360671  }} </ref>
[[Image:West Nile Virus Activity by State.png|thumb|center|1000 px| US West Nile Virus Disease Cases<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention (CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url = http://www.cdc.gov}}</ref></SMALL></SMALL>]]


During the [[outbreak]] of 2012, the [[incidence]] of West Nile virus neuroinvasive disease in Dallas was 7.30 per 100.000 persons.<ref name="ChungBuseman2013">{{cite journal|last1=Chung|first1=Wendy M.|last2=Buseman|first2=Christen M.|last3=Joyner|first3=Sibeso N.|last4=Hughes|first4=Sonya M.|last5=Fomby|first5=Thomas B.|last6=Luby|first6=James P.|last7=Haley|first7=Robert W.|title=The 2012 West Nile Encephalitis Epidemic in Dallas, Texas|journal=JAMA|volume=310|issue=3|year=2013|pages=297|issn=0098-7484|doi=10.1001/jama.2013.8267}}</ref>
==Neuroinvasive disease incidence by state - 2014=
[[Image:West Nile Virus Neuroinvasive Disease Incidence by State.png|center|500px|thumb|Average annual incidence of West Nile Virus neuroinvasive disease 1999-2012<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention (CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url = http://www.cdc.gov}}</ref></SMALL></SMALL>]]


[[Image:West Nile Virus Neuroinvasive Disease Incidence by State.png|center|500px|thumb|Average annual incidence of West Nile Virus neuroinvasive disease 1999-2012<SMALL><SMALL>''[http://www.cdc.gov  - Center for Disease Control and Prevention(CDC)]''<ref name="CDC">{{Cite web | title = Center for Disease Control and Prevention (CDC) | url =  http://www.cdc.gov}}</ref></SMALL></SMALL>]]


<!--
However, serologic surveys and extrapolations from blood donor screening data indicate that neuroinvasive disease following infection is infrequent, with estimates ranging from 1 in 140 to 1 in 256 infections resulting in meningitis or encephalitis [14,27-29].
-->
===Neuroinvasive Disease Archives===
===Neuroinvasive Disease Archives===
<gallery>
<gallery>
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[[Category:Disease]]
[[Category:Disease]]
[[Category:Infectious disease]]
 
[[Category:Neurology]]
[[Category:Neurology]]

Latest revision as of 19:11, 18 September 2017

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]; Michael Maddaleni, B.S.

Overview

WNV is considered a worldwide infective agent. Since most cases are asymptomatic and self-limited, the true incidence and prevalence of West Nile virus fever are often underestimated. Between the years 1999 and 2013, a total of 39557 cases were reported by the CDC in USA alone. The 2002 outbreak in USA marks the WNV outbreak with the most recorded rates of neuroinvasive disease. Nonetheless, only 1/140 to 1/256 cases of West Nile fever are complicated by encephalitis or meningitis. WNV infection occurs predominantly during the end of summer and beginning of fall. Females are more likely to develop WNV infection. The prevalence of the disease is not affected by ethnicity or age, but elderly patients are more likely to experience a complicated clinical course.

Incidence and Prevalence

WNV is widely distributed across Australia, Middle East, Western Russia, Southwestern Asia, Africa and Southern Europe. A series of outbreaks in the Mediterranean basin between 1950 and 1960 and in Europe and Africa between 1970 and 1980, marking a continuously waxing and waning incidence during the second half of the 20th century.[1] In America, the virus was first isolated in 1999 in New York City. The WNV disseminated rapidly across the American continent to the West coast in just 4 years and to Argentina in 6 years.[2][3] The 2002 outbreak in USA marked the highest rate of neuroinvasive disease of a single WNV outbreak. The total number of infected patients reached 4156, with 2942 (71%) of those suffering severe neuroinvasive disease.[4]

Most patients with WNV infection are asymptomatic. Accordingly, West Nile fever is considered to be underreported, either because infected patients do not seek medical attention or because they are not tested for the virus.[3] Between 1999 and 2013, a total 39557 probable and confirmed cases of West Nile fever were reported to the CDC from across the US.[5][2] The outbreak of 2012, in which 2873 cases of neuroinvasive disease were reported, occurred during a period of increased mosquito infection rate. A possible explanation for this was the severe precipitation felt during the previous winter.[6][7]

USA cumulative human disease cases of WNV in 2014. Data as of September 2014- Center for Disease Control and Prevention(CDC)[8]
WNV Cumulative 2014 Data. Data as of September 2014- Center for Disease Control and Prevention(CDC)[8]

Age

  • The prevalence of WNV does not change with age.
  • Elderly patients have a higher risk of developing severe forms of the disease.[1][9]

Gender

WNV is more prevalent in women.[1][9]

Race

The prevalence of WNV does not vary by race or ethnicity.

Season

Infection with WNV commonly occurs during warmer seasons, such as the period between late summer and beginning of fall.[5]

Geographical Distribution

WNV is considered a global virus. Outbreaks of the virus have been documented since its initial isolation in 1937 in approximately all regions of the world.

US disease sases by state - 2014

US West Nile Virus Disease Cases- Center for Disease Control and Prevention( CDC)[8]

West Nile virus by state - 2014

US West Nile Virus Disease Cases- Center for Disease Control and Prevention (CDC)[8]

=Neuroinvasive disease incidence by state - 2014

Average annual incidence of West Nile Virus neuroinvasive disease 1999-2012- Center for Disease Control and Prevention (CDC)[8]


Neuroinvasive Disease Archives

References

  1. 1.0 1.1 1.2 May, F. J.; Davis, C. T.; Tesh, R. B.; Barrett, A. D. T. (2010). "Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas". Journal of Virology. 85 (6): 2964–2974. doi:10.1128/JVI.01963-10. ISSN 0022-538X.
  2. 2.0 2.1 Lindsey NP, Staples JE, Lehman JA, Fischer M, Centers for Disease Control and Prevention (CDC) (2010). "Surveillance for human West Nile virus disease - United States, 1999-2008". MMWR Surveill Summ. 59 (2): 1–17. PMID 20360671.
  3. 3.0 3.1 Petersen LR, Hayes EB (2008). "West Nile virus in the Americas". Med Clin North Am. 92 (6): 1307–22, ix. PMID 19145778.
  4. O'Leary DR, Marfin AA, Montgomery SP, Kipp AM, Lehman JA, Biggerstaff BJ; et al. (2004). "The epidemic of West Nile virus in the United States, 2002". Vector Borne Zoonotic Dis. 4 (1): 61–70. doi:10.1089/153036604773083004. PMID 15018774.
  5. 5.0 5.1 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.
  6. Chung, Wendy M.; Buseman, Christen M.; Joyner, Sibeso N.; Hughes, Sonya M.; Fomby, Thomas B.; Luby, James P.; Haley, Robert W. (2013). "The 2012 West Nile Encephalitis Epidemic in Dallas, Texas". JAMA. 310 (3): 297. doi:10.1001/jama.2013.8267. ISSN 0098-7484.
  7. Goodman, Denise M.; Livingston, Edward H. (2012). "West Nile Virus". JAMA. 308 (10): 1052. doi:10.1001/2012.jama.11678. ISSN 0098-7484.
  8. 8.0 8.1 8.2 8.3 8.4 "Center for Disease Control and Prevention (CDC)".
  9. 9.0 9.1 Zou S, Foster GA, Dodd RY, Petersen LR, Stramer SL (2010). "West Nile fever characteristics among viremic persons identified through blood donor screening". J Infect Dis. 202 (9): 1354–61. doi:10.1086/656602. PMID 20874087.


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