Increasing Seroprevalence In Horses Evidences Widespread Circulation Of West Nile Virus In Albania
DOI:
https://doi.org/10.12834/VetIt.3956.40757.2Keywords:
West Nile Virus, Horses, Seroprevalence, AlbaniaAbstract
West Nile virus (WNV) is a zoonotic mosquito-borne flavivirus that causes West Nile disease, an emerging and re-emerging infection of major global importance. Horses are an important sentinel species for monitoring WNV circulation. Since viraemia in horses is brief and viral loads in the blood are low, serological assays are the primary tools used to monitor WNV exposure. This study aimed to estimate the seroprevalence of WNV antibodies in horses in Albania. Between 2017 and 2020, 509 serum samples were collected from apparently healthy, unvaccinated horses across different regions of the country. Samples were analysed using two commercial ELISA kits for the detection of total WNV-specific antibodies and WNV-specific IgM. Of the 509 samples tested, 143 (28.1%) were positive for total antibodies, while 12 (2.35%) were IgM-positive, indicating recent infection. As no horse tested positive in both assays, the combined seroprevalence was 30.5% (155/509; 95% CI: 26.6–34.6%), without double counting. A subset of 37 ELISA-positive sera was subsequently tested using the virus neutralisation test (VNT), the gold-standard confirmatory assay for WNV-specific antibodies. The VNT confirmed the presence of WNV-neutralising antibodies in 35/37 (94.6%) samples, with titres ranging from 1:10 to 1:640. These findings indicate widespread WNV circulation in Albania. Compared with previous reports based on samples collected in 2010–2011, seropositivity was higher and evidence of exposure was detected in previously unaffected areas, highlighting the need for continued integrated veterinary and public health surveillance.References
Aguilera-Sepúlveda, P., Cano-Gómez, C., Villalba, R., Borges, V., Agüero, M., Bravo-Barriga, D., Frontera, E., Jiménez-Clavero, M. Á., & Fernández-Pinero, J. (2024). The key role of Spain in the traffic of West Nile virus lineage 1 strains between Europe and Africa. Infectious Diseases (London, England), 56(9), 743–758. https://doi.org/10.1080/23744235.2024.2348633.
Bakonyi, T., & Haussig, J. M. (2020). West Nile virus keeps on moving up in Europe. Euro Surveillance: Bulletin Européen sur les Maladies Transmissibles = European Communicable Disease Bulletin, 25(46), 2001938. https://doi.org/10.2807/1560-7917.ES.2020.25.46.2001938.
Bakonyi, T., Ivanics, E., Erdélyi, K., Ursu, K., Ferenczi, E., Weissenböck, H., & Nowotny, N. (2006). Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe. Emerging Infectious Diseases, 12(4), 618–623. https://doi.org/10.3201/eid1204.051379.
Bardos, V., Adamcova, J., Dedei, S., Gjini, N., Rosicky, B., & Simkova, A. (1959). Neutralizing antibodies against some neurotropic viruses determined in human sera in Albania. Journal of Hygiene, Epidemiology, Microbiology, and Immunology, 3, 277–282.
Barzon, L., Montarsi, F., Quaranta, E., Monne, I., Pacenti, M., Michelutti, A., Toniolo, F., Danesi, P., Marchetti, G., Gobbo, F., Sinigaglia, A., Riccetti, S., Dal Molin, E., Favero, L., Russo, F., & Capelli, G. (2022). Early start of seasonal transmission and co-circulation of West Nile virus lineage 2 and a newly introduced lineage 1 strain, northern Italy, June 2022. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, 27(29), 2200548. https://doi.org/10.2807/1560-7917.ES.2022.27.29.2200548
Berxholi, K., Ziegler, U., Rexhepi, A., Schmidt, K., Mertens, M., Korro, K., Cuko, A., Angenvoort, J., & Groschup, M. H. (2013). Indigenous West Nile virus infections in horses in Albania. Transboundary and Emerging Diseases, 60(Suppl. 2), 45–50. https://doi.org/10.1111/tbed.12141.
Di Sabatino, D., Bruno, R., Sauro, F., Danzetta, M. L., Cito, F., Iannetti, S., Narcisi, V., De Massis, F., & Calistri, P. (2014). Epidemiology of West Nile disease in Europe and in the Mediterranean Basin from 2009 to 2013. BioMed Research International, 2014, 907852. https://doi.org/10.1155/2014/907852.
ECDC. (2022). Epidemiological update: West Nile virus transmission season in Europe, 2022. Available from 30 June 2022.
Habarugira, G., Suen, W. W., Hobson-Peters, J., Hall, R. A., & Bielefeldt-Ohmann, H. (2020). West Nile virus: An update on pathobiology, epidemiology, diagnostics, control and “One Health” implications. Pathogens (Basel, Switzerland), 9(7), 589. https://doi.org/10.3390/pathogens9070589.
Jiménez-Clavero, M. A., Llorente, F., Sotelo, E., Soriguer, R., Gómez-Tejedor, C., & Figuerola, J. (2010). West Nile virus serosurveillance in horses in Donana, Spain, 2005 to 2008. The Veterinary Record, 167(10), 379–380. https://doi.org/10.1136/vr.c3155.
Llorente, F., García-Irazábal, A., Pérez-Ramírez, E., Cano-Gómez, C., Sarasa, M., Vázquez, A., & Jiménez-Clavero, M. Á. (2019). Influence of flavivirus co-circulation in serological diagnostics and surveillance: A model of study using West Nile, Usutu and Bagaza viruses. Transboundary and Emerging Diseases, 66(5), 2100–2106. https://doi.org/10.1111/tbed.13262.
Lufo, L., Bizhga, B., Moka, G., & Bërxholi, K. (2023). Serosurvey for detection of equine’s West Nile infection in Albania. Albanian Journal of Agricultural Sciences, 22(Special Issue), 44–50.
Magallanes, S., Llorente, F., Ruiz-López, M. J., Martínez-de la Puente, J., Soriguer, R., Calderon, J., Jímenez-Clavero, M. Á., Aguilera-Sepúlveda, P., & Figuerola, J. (2023). Long-term serological surveillance for West Nile and Usutu virus in horses in south-West Spain. One Health (Amsterdam, Netherlands), 17, 100578. https://doi.org/10.1016/j.onehlt.2023.100578.
Magallanes, S., Llorente, F., Ruiz-López, M. J., Puente, J. M., Ferraguti, M., Gutiérrez-López, R., Soriguer, R., Aguilera-Sepúlveda, P., Fernández-Delgado, R., Jímenez-Clavero, M. Á., & Figuerola, J. (2024). Warm winters are associated to more intense West Nile virus circulation in southern Spain. Emerging Microbes & Infections, 13(1), 2348510. https://doi.org/10.1080/22221751.2024.2348510.
Martin, S. W., Meek, A. H., & Willeberg, P. (1987). Veterinary epidemiology: Principles and methods. Iowa State University Press.
Melnick, J. L., Paul, J. R., Riordan, J. T., Barnett, V. H., Goldblum, N., & Zabin, E. (1951). Isolation from human sera in Egypt of a virus apparently identical to West Nile virus. Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.), 77(4), 661–665. https://doi.org/10.3181/00379727-77-18884.
Morava, K., Postoli, R., Dova, I., Ozuni, E., Rapti, D., Çela, K., & Koleci, X. (2025). First serological evidence of West Nile virus in equine populations from southeastern Albania. European Academic Research, 13(7), 856–864.
Murgue, B., Murri, S., Triki, H., Deubel, V., & Zeller, H. G. (2001). West Nile in the Mediterranean basin: 1950–2000. Annals of the New York Academy of Sciences, 951, 117–126. https://doi.org/10.1111/j.1749-6632.2001.tb02690.x.
Newcombe, R. G., & Altman, D. G. (2000). Proportions and their differences. In D. G. Altman, D. Machin, T. N. Bryant, & M. J. Gardner (Eds.), Statistics with confidence: Confidence intervals and statistical guidelines (2nd ed., pp. 45–56). BMJ Books.
Papa, A., Bakonyi, T., Xanthopoulou, K., Vázquez, A., Tenorio, A., & Nowotny, N. (2011). Genetic characterization of West Nile virus lineage 2, Greece, 2010. Emerging Infectious Diseases, 17(5), 920–922. https://doi.org/10.3201/eid1705.101759.
Petersen, L. R., Brault, A. C., & Nasci, R. S. (2013). West Nile virus: Review of the literature. JAMA, 310(3), 308–315. https://doi.org/10.1001/jama.2013.8042.
Rexhepi, A., Sherifi, K., Berxholi, K., Xhekaj, B., Muja-Bajraktari, N., Özkul, A., von Possel, R., & Emmerich, P. (2021). First serological evidence of West Nile virus among equines and birds in Kosovo, 2018–2019. Vector-Borne and Zoonotic Diseases (Larchmont, N.Y.), 21(2), 116–120. https://doi.org/10.1089/vbz.2020.2673.
Ronca, S. E., Ruff, J. C., & Murray, K K. O. (2021). A 20-year historical review of West Nile virus since its initial emergence in North America: Has West Nile virus become a neglected tropical disease? PLoS Neglected Tropical Diseases, 15(5), e0009190. https://doi.org/10.1371/journal.pntd.0009190.
Smithburn, K. C., Hughes, T. P., Burke, A. W., & Paul, J. H. (1940). A neurotropic virus isolated from the blood of a native of Uganda. The American Journal of Tropical Medicine and Hygiene, s1-20(4), 471–492. https://doi.org/10.4269/ajtmh.1940.s1-20.471.
Thrusfield, M. (2005). Veterinary epidemiology (3rd ed.). Blackwell Science.
Tolnai, C. H., Forgách, P., Marosi, A., Fehér, O., Paszerbovics, B., Tenk, M., Wagenhoffer, Z., & Kutasi, O. (2025). Long-term humoral immune response after West Nile virus convalescence in horses in a geographic area of multiple orthoflavivirus co-circulation. Journal of Veterinary Internal Medicine, 39(4), e70176. https://doi.org/10.1111/jvim.70176.
van der Meulen, K. M., Pensaert, M. B., & Nauwynck, H. J. (2005). West Nile virus in the vertebrate world. Archives of Virology, 150(4), 637–657. https://doi.org/10.1007/s00705-004-0463-z.
Vilibic-Cavlek, T., Savic, V., Petrovic, T., Toplak, I., Barbic, L., Petric, D., Tabain, I., Hrnjakovic-Cvjetkovic, I., Bogdanic, M., Klobucar, A., Mrzljak, A., Stevanovic, V., Dinjar-Kujundzic, P., Radmanic, L., Monaco, F., Listes, E., & Savini, G. (2019). Emerging trends in the epidemiology of West Nile and Usutu virus infections in southern Europe. Frontiers in Veterinary Science, 6, 437. https://doi.org/10.3389/fvets.2019.00437.
Vlaskamp, D. R., Thijsen, S. F., Reimerink, J., Hilkens, P., Bouvy, W. H., Bantjes, S. E., Vlaminckx, B. J., Zaaijer, H., van den Kerkhof, H. H., Raven, S. F., & Reusken, C. B. (2020). First autochthonous human West Nile virus infections in the Netherlands, July to August 2020. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, 25(46), 2001904. https://doi.org/10.2807/1560-7917.ES.2020.25.46.2001904.
WOAH. (2022). Terrestrial animal health code. https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/.
Work, T. H., Hurlbut, H. S., & Taylor, R. M. (1953). Isolation of West Nile virus from hooded crow and rock pigeon in the Nile delta. Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.), 84(3), 719–722. https://doi.org/10.3181/00379727-84-20764.
Ziegler, U., Santos, P. D., Groschup, M. H., Hattendorf, C., Eiden, M., Höper, D., Eisermann, P., Keller, M., Michel, F., Klopfleisch, R., Müller, K., Werner, D., Kampen, H., Beer, M., Frank, C., Lachmann, R., Tews, B. A., Wylezich, C., Rinder, M., Lachmann, L., … Lühken, R. (2020). West Nile virus epidemic in Germany triggered by epizootic emergence, 2019. Viruses, 12(4), 448. https://doi.org/10.3390/v12040448.
