Abstract
The West Nile virus is endemic in multiple European countries and responsible for several epidemics throughout the European region. Its evolution into local or even widespread epidemics is driven by multiple factors from genetic diversification of the virus to environmental conditions. The year of 2018 was characterized by an extraordinary increase in human and animal cases in the Central-Eastern European region, including Hungary. In a collaborative effort, we summarized and analyzed the genetic and serologic data of WNV infections from multiple Hungarian public health institutions, universities, and private organizations. We compared human and veterinary serologic data, along with NS5 and NS3 gene sequence data through 2018. Wild birds were excellent indicator species for WNV circulation in each year. Our efforts resulted in documenting the presence of multiple phylogenetic subclades with Balkans and Western-European progenitor sequences of WNV circulating among human and animal populations in Hungary prior to and during the 2018 epidemic. Supported by our sequence and phylogenetic data, the epidemic of 2018 was not caused by recently introduced WNV strains. Unfortunately, Hungary has no country-wide integrated surveillance system which would enable the analysis of related conditions and provide a comprehensive epidemiological picture. The One Health approach, involving multiple institutions and experts, should be implemented in order to fully understand ecological background factors driving the evolution of future epidemics.
Highlights
Along with other widely distributed flaviviruses, such as the Dengue virus or Yellow Fever virus, the West Nile virus is a major public health concern throughout multiple continents [1]
Horse serologic data was obtained from the University of Veterinary Medicine Budapest, and animal-derived West Nile virus (WNV) sequences were provided by the University of Veterinary Medicine, the National
During the transmission season of 2018, n = 225 autochthonous and imported WNV cases were reported to the European Center for Disease Prevention and Control (ECDC)
Summary
Along with other widely distributed flaviviruses, such as the Dengue virus or Yellow Fever virus, the West Nile virus is a major public health concern throughout multiple continents [1]. Nine genetic variants of the virus have been identified. The infectivity and neuroinvasive tendencies regarding the lineages have been largely different [2,3]. 1 and lineage 2 West Nile virus (ffWNV) strains pose the largest human health risk worldwide [1]. A higher degree of infectivity and neuroinvasiveness was attributed to lineage 1 WNV until the appearance of a large number of lineage 2 WNV strains in South Africa with elevated infectivity and neuroinvasive properties [4]. The West Nile virus is transmitted by mosquitoes belonging to the Culex genus. There is growing concern in reference to the role of recently expanding invasive Aedes mosquitoes throughout
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