Oropouche virus attack rate in an urban setting outside the Amazon Basin: findings from a post-outbreak seroprevalence survey
Year: 2026
Type: article
Study design: Observational Study
Abstract: Background Oropouche virus (OROV) is transmitted by the biting midge Culicoides paraensis . Historically, it was restricted to small outbreaks in the Amazon region. Since 2023, genomic reassortment and human–environment interactions facilitated its geographic expansion, including into urban areas. We estimate the OROV attack rate and identify factors associated with infection in an urban area outside the Amazon. Methods A randomised cross-sectional serosurvey in the urban area of Baturité, Brazil. Households were selected using stratified probability sampling proportional to census tract population; one resident per household was randomly chosen. Participants completed a questionnaire, and serum samples were tested for OROV IgM using MAC-ELISA. Associations were estimated using prevalence ratios (PR) with 95% confidence intervals from Poisson regression with robust variance. Spatial clustering of seropositives was assessed using kernel density and nearest-neighbours. Findings Of 392 participants, 212 were seropositive (54·0%). Most infections were asymptomatic/oligosymptomatic (72·6%–154/212). Living near rivers (PR = 1·80; 95% CI: 1·20–2·50) and working from home (PR = 1·70; 95% CI: 1·30–2·30) were associated with higher prevalence of infection. Clustering of seropositivity was found in census tracts close to cultivated and forested areas, and in central urban neighbourhoods. Interpretation We show large-scale urban OROV transmission, with attack rates exceeding 50%. The high proportion of infections among low mobility individuals suggests peridomestic transmission and vector adaptation to urban microenvironments. Results highlight the need to incorporate OROV into routine surveillance, outbreak preparedness, and differential diagnoses of acute febrile illnesses. Funding Health Surveillance Secretariat/Brazilian Ministry of Health, and Japan International Cooperation Agency.
Authors: Luciano Pamplona de Góes Cavalcanti, Francisca Kalline de Almeida Barreto, Antonio Silva Lima Neto, Rebeca de Souza Oliveira, Higor da Silva Monteiro, Carlos Henrique Alencar, André Ricardo Ribas Freitas, Carlos Garcia Filho, Ana Maria Peixoto Cabral Maia, Caroline Gulen Tangoren, Macleidi Varnier, Fernanda Kézia de Sousa Silva, Eulália Maria Loureiro Maia Campelo, Tânia Mara Silva Coelho, Lauro Vieira Perdigão Neto, Maria Auxiliadora Bessa Santos, Maria Fatima Ferreira de Oliveira, Wanderson Souza Marques, Felipe Gomes Naveca, Matilde del Carmen Contreras Mejía, Ana Beatriz Vieira Muniz, Maria Julia Pessoa Brandão, Chang-Kweng Lim, Shoko Nishiyama, Hiromi Abe-Chayama, Hideki Ebihara, Wildo Navegantes de Araújo, Marcia C. Castro
Institutions: Universidade Federal do Ceará, Unichristus, Escola de Saúde Pública do Ceará, Universidade de Fortaleza, Faculdade São Leopoldo Mandic, Harvard University, Universidade Federal do Rio Grande do Sul, Fiocruz Amazônia, Fundação Oswaldo Cruz, National Institute of Infectious Diseases, Japan Institute for Health Security, Universidade de Brasília
Language: English
Topic: Viral Infections and Vectors
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $4,930
OpenAlex ID: W7221778083