Mem Inst Oswaldo Cruz, Rio de Janeiro, VOLUME 121 | 2026
Research Articles

Sustained Oropouche virus transmission in Rio de Janeiro’s Atlantic Forest: genomic evidence over a two-year period

Ighor Arantes1, Fernanda de Bruycker-Nogueira1, Carla de Oliveira1, Patrícia Carvalho Sequeira1, Otília Lupi2, Michele Borges2, Carolina Lopes Melo2, Michelle Brendolin2, Antonio Braga3, Luciane de Souza Velasque3, Andréa Cony Cavalcanti4, Adriana Cardoso Camargo4, Fábio Burack da Costa5, Cristiane Gomes de Castro Moreira6, Vanessa Zaquieu Dias6, Thiago de Jesus Sousa7, Felipe Donateli Gatti7, Gabriela Colombo de Mendonça7, Joana Zorzal Nodari7, Rodrigo Ribeiro-Rodrigues7,8, Edson Delatorre9, Guilherme Calvet2, Felipe Gomes Naveca1,10, Patricia Brasil2, Ana Maria Bispo de Filippis1, Gonzalo Bello1,+, on behalf of the OROV-Rio de Janeiro Outbreak Response Working Group*

1Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Arbovírus e Vírus Hemorrágicos, Rio de Janeiro, RJ, Brasil
2Fundação Oswaldo Cruz-Fiocruz, Instituto Nacional de Infectologia Evandro Chagas, Laboratório de Doenças Febris Agudas, Rio de Janeiro, RJ, Brasil
3Secretaria de Estado de Saúde do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
4Laboratório Central de Saúde Pública do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
5Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório das Interações Vírus-Hospedeiros, Rio de Janeiro, RJ, Brasil
6Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Virologia, Rio de Janeiro, RJ, Brasil
7Laboratório Central de Saúde Pública do Estado do Espírito Santo, Vitória, ES, Brasil
8Universidade Federal do Espírito Santo, Núcleo de Doenças Infecciosas, Vitória, ES, Brasil
9Universidade Federal do Espírito Santo, Centro de Ciências da Saúde, Departamento de Patologia, Laboratório de Genômica e Ecologia Viral, Vitória, ES, Brasil
10Fundação Oswaldo Cruz-Fiocruz, Instituto Leônidas e Maria Deane, Núcleo de Vigilância de Vírus Emergentes, Reemergentes ou Negligenciados, Manaus, AM, Brasil

DOI: 10.1590/0074-02760250181
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ABSTRACT

BACKGROUND Oropouche virus (OROV), an arbovirus endemic to the Amazon region, has recently expanded into non-endemic areas including Rio de Janeiro State, Brazil.
OBJECTIVE To characterise the spatio-temporal dynamics and ecological factors associated with OROV transmission in Rio de Janeiro during 2024-2025.
METHODS We analysed OROV case-associated ecological factors and performed a phylodynamic analysis on 40 viral genomes, comprising 35 new and five published sequences, sampled from 15 municipalities across the state during 2024-2025.
FINDINGS OROV cases showed significant positive correlations with forest area (r = 0.50, p < 0.0001), banana harvest area
(r = 0.39, p < 0.01), and cassava harvest area (r = 0.29, p < 0.05); but these factors were autocorrelated, suggesting a confounded relationship. We identified two OROV sub-clades circulating in the Rio de Janeiro State. The OROVRJ/ES sub-clade was likely introduced into the Southern Fluminense region around January 2024, spread primarily by short (> 2 km, 50% of events) and mid-distance movements (2-9 km; 30%) with a mean dispersal rate of 0.3 km/day, and seed outbreaks in Metropolitan and Northwest Fluminense regions in 2025. The OROVES-I clade was likely introduced into Central Fluminense and Coastal Lowlands regions, later spreading to the Northern Fluminense region.
MAIN CONCLUSIONS Following its introduction in early 2024, OROV persisted in Rio de Janeiro State by spreading through short-distance movements among municipalities with high forest cover and agricultural areas. The sustained multi-year OROV transmission in the Atlantic Forest biome highlights the potential for establishment of endemic cycles beyond the Amazon region and the need for enhanced surveillance in extra-Amazonian areas, where OROV will evolve in a different ecosystem.

key words: Oropouche virus Oropouche fever Brazil Rio de Janeiro Atlantic forest
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Financial support: CNPq [grant CNPq/MCTI 10/2023 - Faixa B - Grupos Consolidados - Universal 2023 (421620/2023-4), PROEP-IOC-CNPq (442176/2024-4)], FAPERJ (E-26/211.565/2019). IA had support from FAPERJ (grant SEI-260003/019669/2022), GB is supported by CNPq through their productivity research fellowship (304883/2020-4), FGN is supported by CNPq productivity research fellowship (307748/2025-1), PB was supported by CNPq and FAPERJ through their productivity research fellowships (311562/2021-3 and E-26/200.935/2022), ED and RRR are supported by a grant from the State of Espírito Santo Government through the FAPES (grant no. 2025-25N6P-DI 006/2025-SESA/SEAG/FAPES).
IA and FB-N contributed equally to this work.
+ Corresponding author: gbello@ioc.fiocruz.br | ORCID https://orcid.org/0000-0002-2724-2793 
Received 17 July 2025
Accepted 06 December 2025

HOW TO CITE
Arantes I, de Bruycker-Nogueira F, de Oliveira C, Sequeira PC, Lupi O, Borges M, et al. Sustained Oropouche virus transmission in Rio de Janeiro’s Atlantic Forest: genomic evidence over a two-year period. Mem Inst Oswaldo Cruz. 2026; 121: e250181.

HANDLING EDITOR
Mariza Morgado | ORCID https://orcid.org/0000-0002-9304-6184 

 

*Members of the OROV-Rio de Janeiro Outbreak Response Working Group: Cintia Damasceno dos Santos Rodrigues, Carolina Cardoso dos Santos, Juan Carlos Proença Moura, Desiree dos Santos Nunes, Simone Alves Sampaio (Laboratório de Arbovírus e Vírus Hemorrágicos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil); Claudia Maria Braga, Mario Sergio Ribeiro, Debora Fontenelle dos Santos, Silvia Cristina de Carvalho Cardoso, Cristina Giordano, Paula Almeida, (Secretaria de Estado de Saúde do Rio de Janeiro); Lusiele Guaraldo, Luana Damasceno, Thais Pires Trindade, Leticia Lopes Corrêa, Fernanda Moronoe, Heloisa Ferreira, Trevon Fuller, Isabella Moraes, Marise Mattos, Ezequias Batista Martins, Rogério Valls, Anielle Pina Costa, Roxana Flores, Clarisse Bressan, Manuela da Costa Medeiros, Stephanie Penetra, Otávio de Melo Espíndola, (Laboratório de Doenças Febris Agudas, Instituto Nacional de Infectologia Evandro Chagas, FIOCRUZ, Rio de Janeiro, Brazil); Ieda Pereira Ribeiro, Myrna Cristina Bonaldo (Laboratório de Medicina Experimental e Saúde - IOC/Fiocruz - RJ). Elizabeth Portari (Instituto Fernandes Figueira, Fiocruz, RJ).

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