West Nile Virus and Tick-Borne Encephalitis Virus Are Endemic in Equids in Eastern Austria.

Phebe De Heus,Zdenĕk Hubálek,Katharina Dimmel,Norbert Nowotny,Jessika-M V Cavalleri,Victoria Racher,Jolanta Kolodziejek

doi:10.3390/v13091873

Abstract

The emergence of West Nile virus (WNV) and Usutu virus (USUV) in addition to the autochthonous tick-borne encephalitis virus (TBEV) in Europe causes rising concern for public and animal health. The first equine case of West Nile neuroinvasive disease in Austria was diagnosed in 2016. As a consequence, a cross-sectional seroprevalence study was conducted in 2017, including 348 equids from eastern Austria. Serum samples reactive by ELISA for either flavivirus immunoglobulin G or M were further analyzed with the plaque reduction neutralization test (PRNT-80) to identify the specific etiologic agent. Neutralizing antibody prevalences excluding vaccinated equids were found to be 5.3% for WNV, 15.5% for TBEV, 0% for USUV, and 1.2% for WNV from autochthonous origin. Additionally, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to detect WNV nucleic acid in horse sera and was found to be negative in all cases. Risk factor analysis did not identify any factors significantly associated with seropositivity.

Highlights

The increasing emergence of vector-borne viruses in Europe causes rising concern for public and animal health [1,2,3,4,5,6,7,8]
The samples were conveniently collected from horses and donkeys of at least one year of age from patients hospitalized at the University of Veterinary Medicine Vienna and from privately owned, clinically unremarkable equids recruited in eastern Austria
The home yards of the equids were located in five federal states (Vienna, Burgenland, Lower Austria, Upper Austria, and Styria)

Summary

Introduction

The increasing emergence of vector-borne viruses in Europe causes rising concern for public and animal health [1,2,3,4,5,6,7,8]. The genus Flavivirus of the family Flaviviridae incorporates important human and animal arthropod-borne pathogens such as West Nile virus (WNV), Usutu virus (USUV), and tick-borne encephalitis virus (TBEV). Incidences of West Nile disease (WND), USUV infections, and tick-borne encephalitis (TBE). The transmission cycles of WNV and USUV are very similar with birds acting as a reservoir and amplifying host, and mosquitoes (mainly Culex pipiens) being the principal vector [6,8,14,15,16,17]. The first equine case of West Nile neuroinvasive disease (WNND) in Austria was diagnosed in 2016 at the University of Veterinary Medicine of Vienna [16,20]. Of the eleven confirmed WNND cases that were treated at the Equine

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