West Nile Virus Seroprevalence Among Blood Donors in Hungary

West Nile virus (WNV) is one of the most important viral zoonotic infections in Hungary; however, no transfusion-transmitted WNV infections have been confirmed so far. In 2016, the number of clinical cases of WNV reported was 44, but the seasonal WNV screening of whole-blood donors has not yet been implemented. Our aims were to assess the WNV RNA reactivity and the prevalence of WNV-specific antibodies in the samples of blood donors collected in 2016. WNV RNA with Cobas TaqScreen and anti-WNV antibody determination from plasma samples of 2112 donors was performed. Cross-reactivity to tick-borne encephalitis virus was excluded. WNV neutralization test was used for the confirmation of anti-WNV IgG reactive results, and the presence of anti-WNV IgM antibodies was also determined. None of the samples showed WNV RNA reactivity. The total weighted anti-WNV IgG prevalence was 2.34% (95% confidence interval 1.65-3.03), and in addition, three donors were found to be IgM positive. There was a comparable tendency between the data of WNV seroprevalence and cumulative incidence in six out of seven statistical regions in Hungary. Our results show a comparable data with publications that estimated the WNV seroprevalence in some other European endemic areas. As protective measures, both the 30-day deferral of blood donors who spent at least 24 h in WNV-exposed areas and the exclusion of affected Hungarian territories from blood donation are enforced by the Hungarian National Blood Transfusion Service. Our study is the first comprehensive serological survey to obtain actual data about WNV seroprevalence in the Hungarian human population.