Introduction: In Brazil, West Nile virus (WNV) was first detected, in 2018, in horses with neurological disease. Aim: We report the first case of WNV infection in a horse from Ceará state and the complete genome sequence of an isolate from Espírito Santo state. Both infections occurred in 2019. Methods: WNV was isolated from the tissues of a horse with neurological signs in Espírito Santo and sequenced by MiSeq. Results: Phylogenetic analysis revealed that the isolate belongs to lineage 1a, clustering with the NY99 strain, a strain that has not circulated in the USA since 2005. Conclusions: Our findings reinforce the hypothesis that WNV has been silently circulating in Brazil for many years.

IntroductionIn Brazil, West Nile virus (WNV) was first detected in 2018 from horses with neurological disease.AimHere we present the first reported case in Ceará state and complete genome sequence from an isolated in Espírito Santo state from 2019.MethodsThe virus was isolated from a horse that died with neurological signs in Espírito Santo and was sequenced by MiSeq.ResultsPhylogenetic analysis reveals that this isolate belongs to lineage 1a, clustering with NY99 strain, that disappeared from the USA since 2005.ConclusionsOur findings reinforce the hypothesis that WNV has been silently circulating in Brazil for many years.

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