Pautienius et al.
Cross-sectional study on the prevalence and factors influencing occurrence of tick-borne encephalitis virus in horses in Lithuania.
Pathogens. 2021; 10:140,

Various animal species have been evaluated for their potential of tick-borne encephalitis virus, among which are foxes (see Newsletter January 2021) and ducks (see Snapshot week 41/2020).  A research team in Lithuania has now analyzed in a cross-sectional stratified serosurvey and PCR analyses of selected horses in various TBE endemic areas the potential of horses as sentinel.

Blood samples from 301 horses were screened by TBE IgG ELISA and then positive sera were confirmed by neutralization assay. Overall, 37.5% of horses from all counties of Lithuania were positive for TBE. Horses of mixed breed were more susceptible to infection, which may be due to longer periods of time in nature than in stables.

A total of 3.9% of horses were viremic and TBE virus could be isolated. Sequence data based on NS5 from isolates shared high degree of similarity (99.6%) with the European subtype. The TBE virus could also be detected in ticks collected from horses.

An important finding of this study was the absolute seroprevalence and high values of TBE IgG found in horse sera obtained from several locations, indicating a recent infection by TBE virus from previously unknown microfoci close to these equestrian centers. Equines can be attributed as possible TBE virus sentinel species.

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