Surveillance Open Access
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Despite the known circulation of West Nile virus (WNV) and Usutu virus (USUV) in Slovakia, no formal entomological surveillance programme has been established there thus far.


To conduct contemporaneous surveillance of WNV and USUV in different areas of Slovakia and to assess the geographical spread of these viruses through mosquito vectors. The first autochthonous human WNV infection in the country is also described.


Mosquitoes were trapped in four Slovak territorial units in 2018 and 2019. Species were characterised morphologically and mosquito pools screened for WNV and USUV by real-time reverse-transcription PCRs. In pools with any of the two viruses detected, presence of complex group mosquitoes was verified using molecular approaches.


Altogether, 421 pools containing in total 4,508 mosquitoes were screened. Three pools tested positive for WNV and 16 for USUV. USUV was more prevalent than WNV, with a broader spectrum of vectors and was detected over a longer period (June–October vs August for WNV). The main vectors of both viruses were sensu lato. Importantly, WNV and USUV were identified in a highly urbanised area of Bratislava city, Slovakias’ capital city. Moreover, in early September 2019, a patient, who had been bitten by mosquitoes in south-western Slovakia and who had not travelled abroad, was laboratory-confirmed with WNV infection.


The entomological survey results and case report increase current understanding of the WNV and USUV situation in Slovakia. They underline the importance of vector surveillance to assess public health risks posed by these viruses.


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  1. Golding N, Nunn MA, Medlock JM, Purse BV, Vaux AGC, Schäfer SM. West Nile virus vector Culex modestus established in southern England. Parasit Vectors. 2012;5(1):32.  https://doi.org/10.1186/1756-3305-5-32  PMID: 22316288 
  2. 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 
  3. Clé M, Beck C, Salinas S, Lecollinet S, Gutierrez S, Van de Perre P, et al. Usutu virus: A new threat? Epidemiol Infect. 2019;147:e232.  https://doi.org/10.1017/S0950268819001213  PMID: 31364580 
  4. Roesch F, Fajardo A, Moratorio G, Vignuzzi M. Usutu Virus: An arbovirus on the rise. Viruses. 2019;11(7):640.  https://doi.org/10.3390/v11070640  PMID: 31336826 
  5. Pecorari M, Longo G, Gennari W, Grottola A, Sabbatini A, Tagliazucchi S, et al. First human case of Usutu virus neuroinvasive infection, Italy, August-September 2009. Euro Surveill. 2009;14(50):19446.  https://doi.org/10.2807/ese.14.50.19446-en  PMID: 20070936 
  6. European Centre of Disease Prevention and Control (ECDC). Epidemiological Update: West Nile Virus Transmission Season in Europe. 2018. [Accessed 18 Mar 2019]. Available from: https://ecdc.europa.eu/en/news-events/epidemiological-update-west-nile-virus-transmission-season-europe-2018
  7. Gresíková M, Sekeyová M. Haemagglutination-inhibiting antibodies against arboviruses in the population of Slovakia. J Hyg Epidemiol Microbiol Immunol. 1967;11(3):278-85. PMID: 5629947 
  8. Juricová Z, Mitterpák J, Prokopič J, Hubálek Z. Circulation of mosquito-borne viruses in large-scale sheep farms in eastern Slovakia. Folia Parasitol (Praha). 1986;33(3):285-8. PMID: 3758873 
  9. Hubálek Z, Ludvíková E, Jahn P, Treml F, Rudolf I, Svobodová P, et al. West Nile Virus equine serosurvey in the Czech and Slovak republics. Vector Borne Zoonotic Dis. 2013;13(10):733-8.  https://doi.org/10.1089/vbz.2012.1159  PMID: 23919605 
  10. Dorko E, Bušová A, Csank T, Feketeová E, Rimárová K, Diabelková J, et al. West Nile virus - a new infection in the Slovak Republic? Cent Eur J Public Health. 2018;26(Suppl):S51-5.  https://doi.org/10.21101/cejph.a5287  PMID: 30817874 
  11. Labuda M, Kožuch O, Grešíková M. Isolation of West Nile virus from Aedes cantans mosquitoes in West Slovakia. Acta Virol. 1974;18:429-33.
  12. Csank T, Drzewnioková P, Korytár Ľ, Major P, Gyuranecz M, Pistl J, et al. A serosurvey of flavivirus infection in horses and birds in Slovakia. Vector Borne Zoonotic Dis. 2018;18(4):206-13.  https://doi.org/10.1089/vbz.2017.2216  PMID: 29437548 
  13. Csank T, Korytár L, Pošiváková T, Bakonyi T, Pistl J, Csanády A. Surveillance on antibodies against West Nile virus, Usutu virus, tick-borne encephalitis virus and Tribeč virus in wild birds in Drienovská wetland, Slovakia. Biológia.2019;74(7):813-20.  https://doi.org/10.2478/s11756-019-00211-4 
  14. Csank T, Pikalík M, Majláthová V, Majláth I, Pistl J. Detection of neutralizing antibodies against Usutu virus in green lizards (Lacerta viridis) In: Klempa B., Nemčovicová I., Černý J., Tomášková J., Stolt-Bergner P., editors. Book of Abstracts, Joint Czechoslovak Virology Conference 2019 and 1st SK-AT Structural Virology Meeting, Bratislava, Slovakia, 13-15 February 2019. Biology Centre AS CR v.v.i; České Budějovice, Czech Republic: 2019. pp. 78-79.
  15. 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):639.  https://doi.org/10.3390/v11070639  PMID: 31336825 
  16. Becker N, Petric D, Zgomba M, Boase C, Madon M, Dahl C, et al. Mosquitoes and their control. 2nd ed. Springer: Berlin/Heidelberg: Germany; 2010.
  17. Kolodziejek J, Marinov M, Kiss BJ, Alexe V, Nowotny N. The complete sequence of a West Nile virus lineage 2 strain detected in a Hyalomma marginatum marginatum tick collected from a song thrush (Turdus philomelos) in eastern Romania in 2013 revealed closest genetic relationship to strain Volgograd 2007. PLoS One. 2014;9(10):e109905.  https://doi.org/10.1371/journal.pone.0109905  PMID: 25279973 
  18. Weissenböck H, Bakonyi T, Chvala S, Nowotny N. Experimental Usutu virus infection of suckling mice causes neuronal and glial cell apoptosis and demyelination. Acta Neuropathol. 2004;108(5):453-60.  https://doi.org/10.1007/s00401-004-0916-1  PMID: 15372281 
  19. 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 
  20. Tamura K, Stecher G, Peterson D, Filipski A, Kumar S. MEGA6: Molecular Evolutionary Genetics Analysis version 6.0. Mol Biol Evol. 2013;30(12):2725-9.  https://doi.org/10.1093/molbev/mst197  PMID: 24132122 
  21. Smith JL, Fonseca DM. Rapid assays for identification of members of the Culex (Culex) pipiens complex, their hybrids, and other sibling species (Diptera: culicidae). Am J Trop Med Hyg. 2004;70(4):339-45.  https://doi.org/10.4269/ajtmh.2004.70.339  PMID: 15100444 
  22. Bahnck CM, Fonseca DM. Rapid assay to identify the two genetic forms of Culex (Culex) pipiens L. (Diptera: Culicidae) and hybrid populations. Am J Trop Med Hyg. 2006;75(2):251-5.  https://doi.org/10.4269/ajtmh.2006.75.2.0750251  PMID: 16896127 
  23. Čabanová V, Miterpáková M, Valentová D, Blažejová H, Rudolf I, Stloukal E, et al. Urbanization impact on mosquito community and the transmission potential of filarial infection in central Europe. Parasit Vectors. 2018;11(1):261.  https://doi.org/10.1186/s13071-018-2845-1  PMID: 29690912 
  24. 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. Luxembourg: Official Journal of the European Union. 2018; L 170/1. 6.7.2018. [Accessed 22 Sep 2020]. Available from: https://eur-lex.europa.eu/legal content/EN/TXT/?uri=uriserv:OJ.L_.2018.170.01.0001.01.ENG
  25. Engler O, Savini G, Papa A, Figuerola J, Groschup MH, Kampen H, et al. European surveillance for West Nile virus in mosquito populations. Int J Environ Res Public Health. 2013;10(10):4869-95.  https://doi.org/10.3390/ijerph10104869  PMID: 24157510 
  26. Napp S, Petrić D, Busquets N. West Nile virus and other mosquito-borne viruses present in Eastern Europe. Pathog Glob Health. 2018;112(5):233-48.  https://doi.org/10.1080/20477724.2018.1483567  PMID: 29979950 
  27. Bákonyi T, Erdélyi K. Increased bird of prey mortality in Hungary due to West Nile virus infection. Ornis Hungarica.2011;19:1-10.
  28. Nagy A, Mezei E, Nagy O, Bákonyi 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 
  29. Krisztalovics K, Ferenczi E, Molnár Z, Csohán A, Bán E, Zöldi V, et al. West Nile virus infections in Hungary, August-September 2008. Euro Surveill. 2008;13(45):19030.  https://doi.org/10.2807/ese.13.45.19030-en  PMID: 19000572 
  30. Stiasny K, Aberle SW, Heinz FX. Retrospective identification of human cases of West Nile virus infection in Austria (2009 to 2010) by serological differentiation from Usutu and other flavivirus infections. Euro Surveill. 2013;18(43):20614.  https://doi.org/10.2807/1560-7917.ES2013.18.43.20614  PMID: 24176619 
  31. Aberle SW, Kolodziejek J, Jungbauer C, Stiasny K, Aberle JH, Zoufaly A, et al. Increase in human West Nile and Usutu virus infections, Austria, 2018. Euro Surveill. 2018;23(43):1800545.  https://doi.org/10.2807/1560-7917.ES.2018.23.43.1800545  PMID: 30376913 
  32. Csank T, Bhide K, Bencúrová E, Dolinská S, Drzewnioková P, Major P, et al. Detection of West Nile virus and tick-borne encephalitis virus in birds in Slovakia, using a universal primer set. Arch Virol. 2016;161(6):1679-83.  https://doi.org/10.1007/s00705-016-2828-5  PMID: 27001305 
  33. Hönig V, Palus M, Kaspar T, Zemanova M, Majerova K, Hofmannova L, et al. Multiple lineages of Usutu virus (Flaviviridae, Flavivirus) in blackbirds (Turdus merula) and mosquitoes (Culex pipiens, Cx. modestus) in the Czech Republic (2016-2019). Microorganisms. 2019;7(11):568.  https://doi.org/10.3390/microorganisms7110568  PMID: 31744087 
  34. Börstler J, Jöst H, Garms R, Krüger A, Tannich E, Becker N, et al. Host-feeding patterns of mosquito species in Germany. Parasit Vectors. 2016;9(1):318.  https://doi.org/10.1186/s13071-016-1597-z  PMID: 27259984 

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