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West Nile virus (WNV) circulates in an enzootic cycle involving mosquitoes and birds; humans are accidental hosts.


We analysed human WNV infections reported between 2010 and 2018 to the European Centre for Disease Prevention and Control to better understand WNV epidemiology.


We describe probable and confirmed autochthonous human cases of WNV infection reported by European Union (EU) and EU enlargement countries. Cases with unknown clinical manifestation or with unknown place of infection at NUTS 3 or GAUL 1 level were excluded from analysis.


From southern, eastern and western Europe, 3,849 WNV human infections and 379 deaths were reported. Most cases occurred between June and October. Two large outbreaks occurred, in 2010 (n = 391) and in 2018 (n = 1,993). The outbreak in 2018 was larger than in all previous years and the first cases were reported unusually early. The number of newly affected areas (n = 45) was higher in 2018 than in previous years suggesting wider spread of WNV.


Real-time surveillance of WNV infections is key to ensuring that clinicians and public health authorities receive early warning about the occurrence of cases and potential unusual seasonal patterns. Human cases may appear shortly after first detection of animal cases. Therefore, public health authorities should develop preparedness plans before the occurrence of human or animal WNV infections.


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  1. Petersen LR, Brault AC, Nasci RS. West Nile virus: review of the literature. JAMA. 2013;310(3):308-15.  https://doi.org/10.1001/jama.2013.8042  PMID: 23860989 
  2. Bowen RA, Nemeth NM. Experimental infections with West Nile virus. Curr Opin Infect Dis. 2007;20(3):293-7.  https://doi.org/10.1097/QCO.0b013e32816b5cad  PMID: 17471040 
  3. Kramer LD, Li J, Shi PY. West Nile virus. Lancet Neurol. 2007;6(2):171-81.  https://doi.org/10.1016/S1474-4422(07)70030-3  PMID: 17239804 
  4. Lim SM, Koraka P, Osterhaus ADME, Martina BEE. West Nile virus: immunity and pathogenesis. Viruses. 2011;3(6):811-28.  https://doi.org/10.3390/v3060811  PMID: 21994755 
  5. Bardos V, Adamcova J, Dedei S, Gjini N, Rosicky B, Simkova A. Neutralizing antibodies against some neurotropic viruses determined in human sera in Albania. J Hyg Epidemiol Microbiol Immunol. 1959;3:277-82. PMID: 13796704 
  6. Hubálek Z, Halouzka J. West Nile fever--a reemerging mosquito-borne viral disease in Europe. Emerg Infect Dis. 1999;5(5):643-50.  https://doi.org/10.3201/eid0505.990505  PMID: 10511520 
  7. Chaskopoulou A, L’Ambert G, Petric D, Bellini R, Zgomba M, Groen TA, et al. Ecology of West Nile virus across four European countries: review of weather profiles, vector population dynamics and vector control response. Parasit Vectors. 2016;9(1):482.  https://doi.org/10.1186/s13071-016-1736-6  PMID: 27590848 
  8. Rizzo C, Napoli C, Venturi G, Pupella S, Lombardini L, Calistri P, et al. West Nile virus transmission: results from the integrated surveillance system in Italy, 2008 to 2015. Euro Surveill. 2016;21(37):30340.  https://doi.org/10.2807/1560-7917.ES.2016.21.37.30340  PMID: 27684046 
  9. Petrović T, Blázquez AB, Lupulović D, Lazić G, Escribano-Romero E, Fabijan D, et al. Monitoring West Nile virus (WNV) infection in wild birds in Serbia during 2012: first isolation and characterisation of WNV strains from Serbia. Euro Surveill. 2013;18(44):20622.  https://doi.org/10.2807/1560-7917.ES2013.18.44.20622  PMID: 24176657 
  10. Bakonyi T, Ferenczi E, Erdélyi K, Kutasi O, Csörgő T, Seidel B, et al. Explosive spread of a neuroinvasive lineage 2 West Nile virus in Central Europe, 2008/2009. Vet Microbiol. 2013;165(1-2):61-70.  https://doi.org/10.1016/j.vetmic.2013.03.005  PMID: 23570864 
  11. Papa A, Xanthopoulou K, Gewehr S, Mourelatos S. Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece. Clin Microbiol Infect. 2011;17(8):1176-80.  https://doi.org/10.1111/j.1469-0691.2010.03438.x  PMID: 21781205 
  12. Zehender G, Veo C, Ebranati E, Carta V, Rovida F, Percivalle E, et al. Reconstructing the recent West Nile virus lineage 2 epidemic in Europe and Italy using discrete and continuous phylogeography. PLoS One. 2017;12(7):e0179679.  https://doi.org/10.1371/journal.pone.0179679  PMID: 28678837 
  13. Haussig JM, Young JJ, Gossner CM, Mezei E, Bella A, Sirbu A, et al. Early start of the West Nile fever transmission season 2018 in Europe. Euro Surveill. 2018;23(32):1800428.  https://doi.org/10.2807/1560-7917.ES.2018.23.32.1800428  PMID: 30107869 
  14. Gossner CM, Marrama L, Carson M, Allerberger F, Calistri P, Dilaveris D, et al. West Nile virus surveillance in Europe: moving towards an integrated animal-human-vector approach. Euro Surveill. 2017;22(18):30526.  https://doi.org/10.2807/1560-7917.ES.2017.22.18.30526  PMID: 28494844 
  15. European Commission. Commission Decision of 18 December 2007 amending Decision No 2119/98/EC of the European Parliament and of the Council and Decision 2000/96/EC as regards communicable diseases listed in those decisions Brussels: Official Journal of the European Union; 2007. Available from: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32007D0875&from=EN
  16. Dente MG, Riccardo F, Bolici F, Colella NA, Jovanovic V, Drakulovic M, et al. Implementation of the One Health approach to fight arbovirus infections in the Mediterranean and Black Sea Region: Assessing integrated surveillance in Serbia, Tunisia and Georgia. Zoonoses Public Health. 2019;66(3):276-87.  https://doi.org/10.1111/zph.12562  PMID: 30724030 
  17. European Commission. Commission Directive 2014/110/EU of 17 December 2014 amending Directive 2004/33/EC as regards temporary deferral criteria for donors of allogeneic blood donations. Brussels: Official Journal of the European Union; 2014. Available from: http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014L0110&from=EN
  18. European Commission. European Commission. Commission implementing decision (EU) 2018/945 of 22 June 2018 on the communicable diseases and related special health issues to be covered by epidemiological surveillance as well as relevant case definitions. Brussels: Official Journal of the European Union; 2018. Available from: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018D0945&from=EN
  19. Statistical Office of the European Communities (Eurostat). NUTS - Nomenclature of Territorial Units for Statistics. Background. Brussels: Eurostat. [Accessed: 25 Jan 2019]. Available from: http://ec.europa.eu/eurostat/web/nuts/overview
  20. GeoNetwork. Global Administrative Unit Layers (GAUL). Food and Agriculture Organization of the United Nations. [Accesssed: 25 Feb 2019]. Available from: http://www.fao.org/geonetwork/srv/en/metadata.show?id=12691
  21. European Centre for Disease Prevention and Control (ECDC). ECDC Map Maker Tool (EMMa). Stockholm: ECDC. [Accessed: 25 Feb 2020]. Available from: https://www.ecdc.europa.eu/en/publications-data/ecdc-map-maker-tool-emma
  22. Barrett ADT. West Nile in Europe: an increasing public health problem. J Travel Med. 2018;25(1).  https://doi.org/10.1093/jtm/tay096  PMID: 30289526 
  23. Chancey C, Grinev A, Volkova E, Rios M. The global ecology and epidemiology of West Nile virus. BioMed Res Int. 2015;2015:376230.  https://doi.org/10.1155/2015/376230  PMID: 25866777 
  24. Hayes EB, Komar N, Nasci RS, Montgomery SP, O’Leary DR, Campbell GL. Epidemiology and transmission dynamics of West Nile virus disease. Emerg Infect Dis. 2005;11(8):1167-73.  https://doi.org/10.3201/eid1108.050289a  PMID: 16102302 
  25. Paz S. Climate change impacts on West Nile virus transmission in a global context. Philos Trans R Soc Lond B Biol Sci. 2015;370(1665):20130561.  https://doi.org/10.1098/rstb.2013.0561  PMID: 25688020 
  26. Paz S, Semenza JC. Environmental drivers of West Nile fever epidemiology in Europe and Western Asia--a review. Int J Environ Res Public Health. 2013;10(8):3543-62.  https://doi.org/10.3390/ijerph10083543  PMID: 23939389 
  27. Gienapp P, Visser ME. Possible fitness consequences of experimentally advanced laying dates in Great Tits: differences between populations in different habitats. Funct Ecol. 2006;20(1):180-5.  https://doi.org/10.1111/j.1365-2435.2006.01079.x 
  28. Rubolini D, Ambrosini R, Caffi M, Brichetti P, Armiraglio S, Saino N. Long-term trends in first arrival and first egg laying dates of some migrant and resident bird species in northern Italy. Int J Biometeorol. 2007;51(6):553-63.  https://doi.org/10.1007/s00484-007-0094-7  PMID: 17375338 
  29. Samplonius JM, Bartošová L, Burgess MD, Bushuev AV, Eeva T, Ivankina EV, et al. Phenological sensitivity to climate change is higher in resident than in migrant bird populations among European cavity breeders. Glob Change Biol. 2018;24(8):3780-90.  https://doi.org/10.1111/gcb.14160  PMID: 29691942 
  30. Cotar AI, Falcuta E, Prioteasa LF, Dinu S, Ceianu CS, Paz S. Transmission dynamics of the West Nile virus in mosquito vector populations under the influence of weather factors in the Danube Delta, Romania. EcoHealth. 2016;13(4):796-807.  https://doi.org/10.1007/s10393-016-1176-y  PMID: 27709311 
  31. Popescu CP, Florescu SA, Cotar AI, Badescu D, Ceianu CS, Zaharia M, et al. Re-emergence of severe West Nile virus neuroinvasive disease in humans in Romania, 2012 to 2017-implications for travel medicine. Travel Med Infect Dis. 2018;22:30-5.  https://doi.org/10.1016/j.tmaid.2018.03.001  PMID: 29544774 
  32. Veo C, Della Ventura C, Moreno A, Rovida F, Percivalle E, Canziani S, et al. Evolutionary dynamics of the lineage 2 West Nile virus that caused the largest European epidemic: Italy 2011-2018. Viruses. 2019;11(9):E814.  https://doi.org/10.3390/v11090814  PMID: 31484295 
  33. Chaintoutis SC, Papa A, Pervanidou D, Dovas CI. Evolutionary dynamics of lineage 2 West Nile virus in Europe, 2004-2018: Phylogeny, selection pressure and phylogeography. Mol Phylogenet Evol. 2019;141:106617.  https://doi.org/10.1016/j.ympev.2019.106617  PMID: 31521822 
  34. Nagy A, Mezei E, Nagy O, Bakonyi T, Csonka N, Kaposi M, et al. Extraordinary increase in West Nile virus cases and first confirmed human Usutu virus infection in Hungary, 2018. Euro Surveill. 2019;24(28):1900038.  https://doi.org/10.2807/1560-7917.ES.2019.24.28.1900038  PMID: 31311619 
  35. Michel F, Sieg M, Fischer D, Keller M, Eiden M, Reuschel M, et al. Evidence for West Nile virus and Usutu virus infections in wild and resident birds in Germany, 2017 and 2018. Viruses. 2019;11(7):E674.  https://doi.org/10.3390/v11070674  PMID: 31340516 
  36. Čabanová V, Šikutová S, Straková P, Šebesta O, Vichová B, Zubríková D, et al. Co-Circulation of West Nile and Usutu Flaviviruses in Mosquitoes in Slovakia, 2018. Viruses. 2019;11(7):E639.  https://doi.org/10.3390/v11070639  PMID: 31336825 
  37. Vilibic-Cavlek T, Savic V, Sabadi D, Peric L, Barbic L, Klobucar A, et al. Prevalence and molecular epidemiology of West Nile and Usutu virus infections in Croatia in the ‘One health’ context, 2018. Transbound Emerg Dis. 2019;66(5):1946-57.  https://doi.org/10.1111/tbed.13225  PMID: 31067011 
  38. Meister T, Lussy H, Bakonyi T, Sikutová S, Rudolf I, Vogl W, et al. Serological evidence of continuing high Usutu virus (Flaviviridae) activity and establishment of herd immunity in wild birds in Austria. Vet Microbiol. 2008;127(3-4):237-48.  https://doi.org/10.1016/j.vetmic.2007.08.023  PMID: 17869454 
  39. Campbell GL, Marfin AA, Lanciotti RS, Gubler DJ. West Nile virus. Lancet Infect Dis. 2002;2(9):519-29.  https://doi.org/10.1016/S1473-3099(02)00368-7  PMID: 12206968 
  40. Mavrouli M, Vrioni G, Kapsimali V, Tsiamis C, Mavroulis S, Pervanidou D, et al. Reemergence of West Nile virus infections in southern Greece, 2017. Am J Trop Med Hyg. 2019;100(2):420-6.  https://doi.org/10.4269/ajtmh.18-0339  PMID: 30526732 
  41. Nemeth NM, Oesterle PT, Bowen RA. Humoral immunity to West Nile virus is long-lasting and protective in the house sparrow (Passer domesticus). Am J Trop Med Hyg. 2009;80(5):864-9.  https://doi.org/10.4269/ajtmh.2009.80.864  PMID: 19407139 
  42. Nemeth NM, Kratz GE, Bates R, Scherpelz JA, Bowen RA, Komar N. Naturally induced humoral immunity to West Nile virus infection in raptors. EcoHealth. 2008;5(3):298-304.  https://doi.org/10.1007/s10393-008-0183-z  PMID: 18677535 
  43. Kwan JL, Kluh S, Reisen WK. Antecedent avian immunity limits tangential transmission of West Nile virus to humans. PLoS One. 2012;7(3):e34127.  https://doi.org/10.1371/journal.pone.0034127  PMID: 22457819 
  44. Kilpatrick AM, Kramer LD, Jones MJ, Marra PP, Daszak P. West Nile virus epidemics in North America are driven by shifts in mosquito feeding behavior. PLoS Biol. 2006;4(4):e82.  https://doi.org/10.1371/journal.pbio.0040082  PMID: 16494532 
  45. Rudolf I, Bakonyi T, Šebesta O, Mendel J, Peško J, Betášová L, et al. Co-circulation of Usutu virus and West Nile virus in a reed bed ecosystem. Parasit Vectors. 2015;8(1):520.  https://doi.org/10.1186/s13071-015-1139-0  PMID: 26459018 
  46. Tran A, Sudre B, Paz S, Rossi M, Desbrosse A, Chevalier V, et al. Environmental predictors of West Nile fever risk in Europe. Int J Health Geogr. 2014;13(1):26.  https://doi.org/10.1186/1476-072X-13-26  PMID: 24986363 
  47. Robert Koch Institut (RKI). Weitere in Deutschland übertragene Fälle von West-Nil-Virus-Infektion. [Further cases of West Nile virus infection transmitted in Germany]. Berlin: RKI; 2019. German. Available from: https://www.rki.de/DE/Content/Infekt/EpidBull/Archiv/2019/43/Art_02.html
  48. Ziegler U, Lühken R, Keller M, Cadar D, van der Grinten E, Michel F, et al. West Nile virus epizootic in Germany, 2018. Antiviral Res. 2019;162:39-43.  https://doi.org/10.1016/j.antiviral.2018.12.005  PMID: 30550796 
  49. Seidowski D, Ziegler U, von Rönn JA, Müller K, Hüppop K, Müller T, et al. West Nile virus monitoring of migratory and resident birds in Germany. Vector Borne Zoonotic Dis. 2010;10(7):639-47.  https://doi.org/10.1089/vbz.2009.0236  PMID: 20854016 
  50. Sirbu A, Ceianu CS, Panculescu-Gatej RI, Vazquez A, Tenorio A, Rebreanu R, et al. Outbreak of West Nile virus infection in humans, Romania, July to October 2010. Euro Surveill. 2011;16(2):19762.  https://doi.org/10.2807/ese.16.02.19762-en  PMID: 21251489 
  51. Rudolf I, Betášová L, Blažejová H, Venclíková K, Straková P, Šebesta O, et al. West Nile virus in overwintering mosquitoes, central Europe. Parasit Vectors. 2017;10(1):452.  https://doi.org/10.1186/s13071-017-2399-7  PMID: 28969685 
  52. Mori H, Wu J, Ibaraki M, Schwartz FW. Key factors influencing the incidence of West Nile virus in Burleigh County, North Dakota. Int J Environ Res Public Health. 2018;15(9):1928.  https://doi.org/10.3390/ijerph15091928  PMID: 30189592 
  53. Calistri P, Giovannini A, Hubalek Z, Ionescu A, Monaco F, Savini G, et al. Epidemiology of west nile in europe and in the mediterranean basin. Open Virol J. 2010;4(1):29-37.  https://doi.org/10.2174/1874357901004010029  PMID: 20517490 
  54. Hernández-Triana LM, Jeffries CL, Mansfield KL, Carnell G, Fooks AR, Johnson N. Emergence of west nile virus lineage 2 in europe: a review on the introduction and spread of a mosquito-borne disease. Front Public Health. 2014;2:271.  https://doi.org/10.3389/fpubh.2014.00271  PMID: 25538937 
  55. Kain MP, Bolker BM. Predicting West Nile virus transmission in North American bird communities using phylogenetic mixed effects models and eBird citizen science data. Parasit Vectors. 2019;12(1):395.  https://doi.org/10.1186/s13071-019-3656-8  PMID: 31395085 
  56. European Centre for Disease Prevention and Control (ECDC). West Nile virus infection. In: ECDC. Annual epidemiological report for 2017. Stockholm: ECDC; 2019. Available from: https://www.ecdc.europa.eu/sites/default/files/documents/AER_for_2017-West-Nile-virus-infection.pdf
  57. Riccardo F, Monaco F, Bella A, Savini G, Russo F, Cagarelli R, et al. An early start of West Nile virus seasonal transmission: the added value of One Heath surveillance in detecting early circulation and triggering timely response in Italy, June to July 2018. Euro Surveill. 2018;23(32):1800427.  https://doi.org/10.2807/1560-7917.ES.2018.23.32.1800427  PMID: 30107870 
  58. Nasci RS, Savage HM, White DJ, Miller JR, Cropp BC, Godsey MS, et al. West Nile virus in overwintering Culex mosquitoes, New York City, 2000. Emerg Infect Dis. 2001;7(4):742-4.  https://doi.org/10.3201/eid0704.017426  PMID: 11585542 
  59. Domanović D, Gossner CM, Lieshout-Krikke R, Mayr W, Baroti-Toth K, Dobrota AM, et al. West Nile and Usutu virus infections and challenges to blood safety in the European Union. Emerg Infect Dis. 2019;25(6):1050-7.  https://doi.org/10.3201/eid2506.181755  PMID: 31107223 
  60. Kolodziejek J, Seidel B, Jungbauer C, Dimmel K, Kolodziejek M, Rudolf I, et al. West Nile virus positive blood donation and subsequent entomological investigation, Austria, 2014. PLoS One. 2015;10(5):e0126381.  https://doi.org/10.1371/journal.pone.0126381  PMID: 25961567 
  61. European Centre for Disease Prevention and Control (ECDC). Factsheet about West Nile virus infection. Stockholm: ECDC. [Accessed: 25 Feb 2020]. Available from: https://www.ecdc.europa.eu/en/west-nile-fever/facts/factsheet-about-west-nile-fever

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