Rocio virus sustained circulation in Brazil: first infection case in a horse highlights the need for enhanced arbovirus surveillance

Archives of Virology 2026 Open access

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Authors: Tiago Gräf, Maria Constanza Rodriguez, Yara de Oliveira Brandão, Carla Adriane Royer, Caroline do Nascimento Ferreira, Camila Confortin, Camila Zanluca, Daisy Maria Strottmann, C. C. dos Santos, Mara Eliza Gasino Joineau
DOI: 10.1007/s00705-026-06574-9
Cited by: 1
References: 17

Abstract

Rocio virus (ROCV), a neurotropic arbovirus of the Orthoflavivirus genus, caused Brazil’s largest encephalitis outbreak in the 1970s but has since been rarely detected. We report the first ROCV encephalitis clinical case after nearly 40 years and isolated and sequenced the virus from CNS tissue of a horse. Metatranscriptomics enabled full-genome sequencing, revealing divergence from the reference sequence at an evolutionary rate of 5.8–7.0 × 10⁻⁴, consistent with Orthoflavivirus. Thirty-one non-synonymous substitutions were identified, with the envelope protein most affected. Findings indicate ROCV cryptic circulation and ongoing evolution. Horses may act as sentinels, underscoring the need for strengthened ROCV genomic surveillance.

Fields of Study & Subjects

Viral Infections and Immunology Research Herpesvirus Infections and Treatments Mosquito-borne diseases and control

Publication details

Journal / source
Archives of Virology
Publisher
Springer Science and Business Media LLC
Volume
171
Issue
4
Publication date
28 February 2026
Language
EN