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Human cases of West Nile virus (WNV) infection are recorded since 2010 in Greece, with seasonal outbreaks occurring almost annually. Enhanced surveillance has been implemented since 2010, to promptly characterise cases’ temporal and geographical distribution and inform authorities for implementation of appropriate measures (mosquito control, health education, blood safety).


We describe the epidemiology of WNV human infections in Greece focusing on the 2018 season.


The National Public Health Organization advised physicians to test all suspect WNV infection cases and refer samples to reference laboratories. Laboratories notified diagnosed cases on a daily basis. Treating physicians, patients, and infected blood donors were interviewed within 48 hours after diagnosis and the probable infection location was identified. Hospitalised cases were followed up until discharge.


A total of 317 autochthonous WNV infection cases were diagnosed in 2018. Among them, 243 cases had neuroinvasive disease (WNND), representing a 23% increase of WNND cases compared with 2010, the previous most intense season. There were 51 deaths. Cases started occurring from week 22, earlier than usual. Both rural and urban areas were affected, with 86 (26% of the total) municipalities belonging to seven (54% of the total) regions recording cases. Two major epicentres were identified in Attica and Central Macedonia regions.


The largest number of human cases of WNV infection ever recorded in Greece occurred in 2018, with a wide geographical distribution, suggesting intense virus circulation. Enhanced surveillance is vital for the early detection of human cases and the prompt implementation of response measures.


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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. Colpitts TM, Conway MJ, Montgomery RR, Fikrig E. West Nile Virus: biology, transmission, and human infection. Clin Microbiol Rev. 2012;25(4):635-48.  https://doi.org/10.1128/CMR.00045-12  PMID: 23034323 
  4. 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 
  5. 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 
  6. Sambri V, Capobianchi M, Charrel R, Fyodorova M, Gaibani P, Gould E, et al. West Nile virus in Europe: emergence, epidemiology, diagnosis, treatment, and prevention. Clin Microbiol Infect. 2013;19(8):699-704.  https://doi.org/10.1111/1469-0691.12211  PMID: 23594175 
  7. Lim SM, Koraka P, Osterhaus AD, Martina BE. West Nile virus: immunity and pathogenesis. Viruses. 2011;3(6):811-28.  https://doi.org/10.3390/v3060811  PMID: 21994755 
  8. European Centre for Disease Prevention and Control (ECDC). Factsheet about West Nile virus infection Stockholm: ECDC; 29 Nov 2018. Available from: https://www.ecdc.europa.eu/en/west-nile-fever/facts/factsheet-about-west-nile-fever
  9. European Centre for Disease Prevention and Control (ECDC). West Nile virus infection. Annual epidemiological report for 2018. Stockholm: ECDC; 2019. Available from: https://www.ecdc.europa.eu/en/publications-data/west-nile-virus-infection-annual-epidemiological-report-2018
  10. 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 
  11. Rappole JH, Hubálek Z. Migratory birds and West Nile virus. J Appl Microbiol. 2003;94(s1) Suppl;47S-58S.  https://doi.org/10.1046/j.1365-2672.94.s1.6.x  PMID: 12675936 
  12. Rappole JH, Derrickson SR, Hubálek Z. Migratory birds and spread of West Nile virus in the Western Hemisphere. Emerg Infect Dis. 2000;6(4):319-28.  https://doi.org/10.3201/eid0604.000401  PMID: 10905964 
  13. Reed KD, Meece JK, Henkel JS, Shukla SK. Birds, migration and emerging zoonoses: west nile virus, lyme disease, influenza A and enteropathogens. Clin Med Res. 2003;1(1):5-12.  https://doi.org/10.3121/cmr.1.1.5  PMID: 15931279 
  14. Owen J, Moore F, Panella N, Edwards E, Bru R, Hughes M, et al. Migrating Birds as Dispersal Vehicles for West Nile Virus. EcoHealth. 2006;3(2):79-85.  https://doi.org/10.1007/s10393-006-0025-9 
  15. Gale P, Johnson N. Chapter 7 - The Role of Birds in the Spread of West Nile Virus. In: Johnson N, editor. The Role of Animals in Emerging Viral Diseases. Boston: Academic Press; 2014. p. 143-67.
  16. Bakonyi T, Ivanics E, Erdélyi K, Ursu K, Ferenczi E, Weissenböck H, et al. Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe. Emerg Infect Dis. 2006;12(4):618-23.  https://doi.org/10.3201/eid1204.051379  PMID: 16704810 
  17. 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 
  18. Di Sabatino D, Bruno R, Sauro F, Danzetta ML, Cito F, Iannetti S, et al. Epidemiology of West Nile disease in Europe and in the Mediterranean Basin from 2009 to 2013. BioMed Res Int. 2014;2014:907852.  https://doi.org/10.1155/2014/907852  PMID: 25302311 
  19. 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 
  20. Zeller HG, Schuffenecker I. West Nile virus: an overview of its spread in Europe and the Mediterranean basin in contrast to its spread in the Americas. Eur J Clin Microbiol Infect Dis. 2004;23(3):147-56.  https://doi.org/10.1007/s10096-003-1085-1  PMID: 14986160 
  21. 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 
  22. Rizzo C, Napoli C, Venturi G, Pupella S, Lombardini L, Calistri P, et al. , Italian WNV surveillance working group. 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 
  23. 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 
  24. 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 
  25. 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 
  26. 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 
  27. 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 
  28. European Centre for Disease Prevention and Control (ECDC). West Nile virus infection. Stockholm: ECDC. [Accessed: 20 Jan 2020]. Available from: https://www.ecdc.europa.eu/en/west-nile-virus-infection
  29. Danis K, Papa A, Theocharopoulos G, Dougas G, Athanasiou M, Detsis M, et al. Outbreak of West Nile virus infection in Greece, 2010. Emerg Infect Dis. 2011;17(10):1868-72.  https://doi.org/10.3201/eid1710.110525  PMID: 22000357 
  30. Papa A, Danis K, Baka A, Bakas A, Dougas G, Lytras T, et al. Ongoing outbreak of West Nile virus infections in humans in Greece, July-August 2010. Euro Surveill. 2010;15(34):19644.  https://doi.org/10.2807/ese.15.34.19644-en  PMID: 20807489 
  31. 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 
  32. National Public Health Organization (NPHO). West Nile Virus infection, Annual epidemiological data 2010, 2011, 2012, 2013, 2014, 2017. Available from: https://eody.gov.gr/en/epidemiological-statistical-data/annual-epidemiological-data/
  33. Danis K, Papa A, Papanikolaou E, Dougas G, Terzaki I, Baka A, et al. Ongoing outbreak of West Nile virus infection in humans, Greece, July to August 2011. Euro Surveill. 2011;16(34):19951. PMID: 21903037 
  34. Pervanidou D, Detsis M, Danis K, Mellou K, Papanikolaou E, Terzaki I, et al. West Nile virus outbreak in humans, Greece, 2012: third consecutive year of local transmission. Euro Surveill. 2014;19(13):20758.  https://doi.org/10.2807/1560-7917.ES2014.19.13.20758  PMID: 24721540 
  35. 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 
  36. Papa A, Papadopoulou E, Gavana E, Kalaitzopoulou S, Mourelatos S. Detection of West Nile virus lineage 2 in Culex mosquitoes, Greece, 2012. Vector Borne Zoonotic Dis. 2013;13(9):682-4.  https://doi.org/10.1089/vbz.2012.1212  PMID: 23697769 
  37. Papa A, Bakonyi T, Xanthopoulou K, Vázquez A, Tenorio A, Nowotny N. Genetic characterization of West Nile virus lineage 2, Greece, 2010. Emerg Infect Dis. 2011;17(5):920-2.  https://doi.org/10.3201/eid1705.101759  PMID: 21529413 
  38. Papa A, Politis C, Tsoukala A, Eglezou A, Bakaloudi V, Hatzitaki M, et al. West Nile virus lineage 2 from blood donor, Greece. Emerg Infect Dis. 2012;18(4):688-9.  https://doi.org/10.3201/eid1804.110771  PMID: 22469502 
  39. Papa A, Xanthopoulou K, Tsioka A, Kalaitzopoulou S, Mourelatos S. West Nile virus in mosquitoes in Greece. Parasitol Res. 2013;112(4):1551-5.  https://doi.org/10.1007/s00436-013-3302-x  PMID: 23371497 
  40. Barzon L, Papa A, Pacenti M, Franchin E, Lavezzo E, Squarzon L, et al. Genome sequencing of West Nile Virus from human cases in Greece, 2012. Viruses. 2013;5(9):2311-9.  https://doi.org/10.3390/v5092311  PMID: 24064795 
  41. Papa A, Testa T, Papadopoulou E. Detection of West Nile virus lineage 2 in the urine of acute human infections. J Med Virol. 2014;86(12):2142-5.  https://doi.org/10.1002/jmv.23949  PMID: 24760617 
  42. Papa A, Papadopoulou E, Kalaitzopoulou S, Tsioka K, Mourelatos S. Detection of West Nile virus and insect-specific flavivirus RNA in Culex mosquitoes, central Macedonia, Greece. Trans R Soc Trop Med Hyg. 2014;108(9):555-9.  https://doi.org/10.1093/trstmh/tru100  PMID: 25033823 
  43. Barzon L, Papa A, Lavezzo E, Franchin E, Pacenti M, Sinigaglia A, et al. Phylogenetic characterization of Central/Southern European lineage 2 West Nile virus: analysis of human outbreaks in Italy and Greece, 2013-2014. Clin Microbiol Infect. 2015;21(12):1122.e1-10.  https://doi.org/10.1016/j.cmi.2015.07.018  PMID: 26235197 
  44. Mavridis K, Fotakis EA, Kioulos I, Mpellou S, Konstantas S, Varela E, et al. Detection of West Nile Virus - Lineage 2 in Culex pipiens mosquitoes, associated with disease outbreak in Greece, 2017. Acta Trop. 2018;182:64-8.  https://doi.org/10.1016/j.actatropica.2018.02.024  PMID: 29474832 
  45. Bouzalas IG, Diakakis N, Chaintoutis SC, Brellou GD, Papanastassopoulou M, Danis K, et al. Emergence of Equine West Nile Encephalitis in Central Macedonia, Greece, 2010. Transbound Emerg Dis. 2016;63(6):e219-27.  https://doi.org/10.1111/tbed.12334  PMID: 25660661 
  46. Valiakos G, Papaspyropoulos K, Giannakopoulos A, Birtsas P, Tsiodras S, Hutchings MR, et al. Use of wild bird surveillance, human case data and GIS spatial analysis for predicting spatial distributions of West Nile virus in Greece. PLoS One. 2014;9(5):e96935.  https://doi.org/10.1371/journal.pone.0096935  PMID: 24806216 
  47. Valiakos G, Touloudi A, Iacovakis C, Athanasiou L, Birtsas P, Spyrou V, et al. Molecular detection and phylogenetic analysis of West Nile virus lineage 2 in sedentary wild birds (Eurasian magpie), Greece, 2010. Euro Surveill. 2011;16(18):19862. PMID: 21586266 
  48. European Commission. Commission Decision of 28/IV/2008 amending Decision 2002/253/EC laying down case definitions for reporting communicable diseases to the Community network under Decision No 2119/98/EC of the European Parliament and of the Council. Official Journal of the European Union. Luxembourg: Publications Office of the European Union. 18.06.2008:L 159. Available from: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=OJ:L:2008:159:FULL&from=EN
  49. Kumar S, Stecher G, Tamura K. MEGA7: Molecular Evolutionary Genetics Analysis Version 7.0 for Bigger Datasets. Mol Biol Evol. 2016;33(7):1870-4.  https://doi.org/10.1093/molbev/msw054  PMID: 27004904 
  50. Commission Directive. 2004/33/EC of 22 March 2004 implementing Directive 2002/98/EC of the European Parliament and of the Council as regards certain technical requirements for blood and blood components. Official Journal of the European Union Luxembourg: Publications Office of the European Union. 30.3.2004:L91. Available from: https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2004:091:0025:0039:EN:PDF
  51. EpochCoverter. Week Numbers for 2018. ISO week date standard (ISO-8601); 2018. Available from: https://www.epochconverter.com/weeks/2018
  52. Papa A, Papadopoulou E, Chatzixanthouliou C, Glouftsios P, Pappa S, Pervanidou D, et al. Emergence of West Nile virus lineage 2 belonging to the Eastern European subclade, Greece. Arch Virol. 2019;164(6):1673-5.  https://doi.org/10.1007/s00705-019-04243-8  PMID: 30953205 
  53. 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 
  54. World Health Organization Regional Office for Europe (WHO/Europe). West Nile virus infections spike in southern and central Europe. Copenhagen: WHO/Europe; 21 Aug 2018. Available from: http://www.euro.who.int/en/countries/italy/news/news/2018/8/west-nile-virus-infections-spike-in-southern-and-central-europe
  55. European Centre for Medium-Range Weather Forecasts (ECMWF). Copernicus Climate Change Service. European State of the Climate 2018. ECMWF. 2018. Available from: https://climate.copernicus.eu/european-temperature
  56. Mamara A, Chatziapostolou E, Karatarakis N. Significant weather & climate events in Greece during 2018. Athens: Hellenic National Meteorological Service, Climatology – Application Division, Department of Climatology. [Accessed 15 Jan 2020]. Available from: http://www.emy.gr/emy/en/pdf/2018_GRsignificantEVENT_en.pdf
  57. European Centre for Disease Prevention and Control (ECDC). West Nile virus infection outbreak in humans in Central Macedonia, Greece. July–August 2010. Stockholm: ECDC; Oct 2010. Available from: https://www.ecdc.europa.eu/sites/default/files/media/en/publications/Publications/1001_MIR_West_Nile_virus_infection_outbreak_humans_Central_Macedonia_Greece.pdf
  58. 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 
  59. 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 
  60. 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 
  61. Young JJ, Coulombier D, Domanović D, Zeller H, Gossner CM, European Union West Nile Fever Working Group. One Health approach for West Nile virus surveillance in the European Union: relevance of equine data for blood safety. Euro Surveill. 2019;24(16):1800349.  https://doi.org/10.2807/1560-7917.ES.2019.24.16.1800349  PMID: 31014416 
  62. Riccardo F, Bolici F, Fafangel M, Jovanovic V, Socan M, Klepac P, et al. Strengthening preparedness for West Nile Virus in Europe following the 2018 transmission season: an ECDC protocol to conduct After Action Reviews. ESCAIDE; 27-29 Nov 2019; Stockholm: ESCAIDE. Available from: https://www.escaide.eu/sites/default/files/documents/ESCAIDE-abstract-book-2019.pdf
  63. Hellenic Statistical Authority. (EL. STAT.). Estimated population by sex and 5 year age groups on 1st January (Years 1991 - 2012). Piraeus: EL. STAT. [Accessed 15 Jun 2019]. Available from: https://www.statistics.gr/en/statistics/-/publication/SPO18/-

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