Sociodemographic characteristics, clinical manifestations, and concurrent outcomes of Oropouche fever and dengue in Espírito Santo, Brazil.

Objective: To compare sociodemographic and clinical characteristics and the outcome severity between confirmed cases of Oropouche fever and dengue in the state of Espírito Santo, Brazil. Methods: A cross-sectional study used secondary data from the state health surveillance system of Espírito Santo, 2024-2025. The study includes laboratory-confirmed cases of Oropouche fever and dengue. The authors calculated absolute and relative frequencies of variables. Pearson's chi-square and Fisher's exact tests assessed differences. Firth's penalized logistic regression estimated odds ratios (OR) for severe manifestations and death, with 95% confidence intervals (95% CI). Results: A total of 12 135 OF cases and 18 018 dengue cases were confirmed. Compared with dengue cases, Oropouche fever was more prevalent among males (53.5%), white individuals (56.3%), and residents of rural and peri-urban areas (52.1%). Fever (84.5% vs. 78.7%), headache (83.9% vs. 72.1%), and myalgia (76.5% vs. 67.5%) were the most common symptoms in both groups, with significantly higher proportions among Oropouche fever cases. Dengue cases showed higher odds of progressing to severe disease (OR 15.35; 95% CI 10.60-22.23) and death (OR 2.09; 95% CI 1.10-3.98). Conclusion: Oropouche fever and dengue presented overlapping clinical profiles; however, Oropouche fever was more frequent in rural and peri-urban areas. Dengue was associated with greater severity and lethality. These findings underscore the importance of surveillance to support strategies for monitoring, clinical management, and control, while accounting for the distinct epidemiological and clinical profiles of Oropouche fever and dengue.