West nile virus epidemiology and demographics: Difference between revisions

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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>
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>


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>
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>




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The most accurate trend data derive from monitoring cases of invasive neurologic disease [21]. From 1999 to 2013, a total of 39,557 confirmed and probable cases of WN virus disease, including 17,463 (44 percent) cases of neuroinvasive disease, were reported to the CDC from 48 states and the District of Columbia [4,22]. Only 19 human cases of WN neuroinvasive disease were reported in the United States in 2000 and 64 in 2001 [23]. However, from 2002 to 2012, the number of reported neuroinvasive disease cases ranged from 386 to 2946, with the three largest outbreaks occurring in 2002 (2946 cases), 2003 (2866 cases), and 2012 (2873 cases) [4]. Neuroinvasive disease varies considerably across the United States, with the highest incidence states located throughout the Midwest (figure 1).
Only 19 human cases of WN neuroinvasive disease were reported in the United States in 2000 and 64 in 2001 [23]. However, from 2002 to 2012, the number of reported neuroinvasive disease cases ranged from 386 to 2946, with the three largest outbreaks occurring in 2002 (2946 cases), 2003 (2866 cases), and 2012 (2873 cases) [4]. Neuroinvasive disease varies considerably across the United States, with the highest incidence states located throughout the Midwest (figure 1).


A large multistate outbreak in 2012 was widespread, with 43 states reporting a higher incidence of neuroinvasive disease in 2012 compared with the median for 2004-2011; more than half of these cases were reported from four states and 29 percent were reported from Texas alone [24]. The incidence rate of WN neuroinvasive disease in Dallas county was 7.30 per 100,000 residents in 2012, which was significantly higher than the largest previous Dallas country outbreak of 2.91 per 100,000 in 2006 [25]. The 2012 outbreak followed markedly increased infection rates in mosquitos, this was felt to be due in part to a mild preceding winter and excess precipitation [25,26].
A large multistate outbreak in 2012 was widespread, with 43 states reporting a higher incidence of neuroinvasive disease in 2012 compared with the median for 2004-2011; more than half of these cases were reported from four states and 29 percent were reported from Texas alone [24]. The incidence rate of WN neuroinvasive disease in Dallas county was 7.30 per 100,000 residents in 2012, which was significantly higher than the largest previous Dallas country outbreak of 2.91 per 100,000 in 2006 [25]. The 2012 outbreak followed markedly increased infection rates in mosquitos, this was felt to be due in part to a mild preceding winter and excess precipitation [25,26].

Revision as of 01:35, 12 September 2014

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

Overview

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.[1]

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.[2][3]

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.[3] Between 1999 and 2013, 39 557 probable and confirmed cases of West Nile fever were reported to the CDC, from across the US.[4][2]


USA cumulative human disease cases of WNV in 2014. Data as of September 2014- Center for Disease Control and Prevention(CDC)[5]
WNV Cumulative 2014 Data. Data as of September 2014- Center for Disease Control and Prevention(CDC)[5]

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.[1][6]

Gender

The female gender is more prone to develop West Nile fever following infection with the WNV.[1][6]

Geographical Distribution

US Disease Cases by State 2014

US West Nile Virus Disease Cases- Center for Disease Control and Prevention(CDC)[5]

West Nile Virus by State 2014

US West Nile Virus Disease Cases- Center for Disease Control and Prevention(CDC)[5]

Neuroinvasive Disease Incidence 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.[1] Despite this, during an outbreak, only 40% of the cases who presented with compatible meningitis or encephalitis were tested for infection with the virus.[7] Between 1999 and 2012, 16 196 cases of neuroinvasive disease by WNV, and 1549 fatalities were reported in the United Stated. Although the number varies every year, some areas of the US are more affected by this form of the disease.[2]

Average annual incidence of West Nile Virus neuroinvasive disease 1999-2012- Center for Disease Control and Prevention(CDC)[5]

Neuroinvasive Disease Archives

References

  1. 1.0 1.1 1.2 1.3 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 2.2 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. 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.
  5. 5.0 5.1 5.2 5.3 5.4 "Center for Disease Control and Prevention (CDC)".
  6. 6.0 6.1 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.
  7. Weber IB, Lindsey NP, Bunko-Patterson AM, Briggs G, Wadleigh TJ, Sylvester TL; et al. (2012). "Completeness of West Nile virus testing in patients with meningitis and encephalitis during an outbreak in Arizona, USA". Epidemiol Infect. 140 (9): 1632–6. doi:10.1017/S0950268811002494. PMID 22123531.


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