A new study involving the D’Or Institute for Research and Education (IDOR) mapped the environmental factors and the most vulnerable regions for Oropouche virus transmission, which is currently causing outbreaks in several Brazilian states and other parts of Latin America. 

Since late 2023, the region has seen an unprecedented surge in Oropouche Fever cases. Once confined to the Amazon, the virus has now reached coastal regions, multiple Brazilian states, and parts of Central America. In 2023, Brazil recorded fewer than 900 confirmed cases; by 2024, that number had jumped to over 13,000. As of 2025, nearly 8,000 cases had already been reported — about half in January alone, coinciding with extreme weather events during the summer. 

To understand this rapid spread, researchers from six Latin American countries (Brazil, Bolivia, Colombia, Costa Rica, Ecuador, and Peru) analyzed more than 9,000 blood samples collected between 2001 and 2022 using serological and genetic tests. The goal was to identify long-term infection patterns and develop predictive risk models based on socio-environmental variables. 

The average antibody detection rate was 6.3%, with significant regional variations. According to the serological model, high-risk areas included the Amazon basin, coastal zones, southern Brazil, Central America, and Caribbean islands — matching current outbreak reports from the Pan American Health Organization. 

Although no recent mutations in the virus were detected, the study revealed a strong correlation between outbreaks and climate variables. Over 60% of the transmission risk could be attributed to temperature and rainfall levels. The El Niño phenomenon, which warms Pacific waters and alters weather patterns, was identified as a likely driver of the 2023 and 2024 outbreaks. 

Using advanced machine learning techniques, the researchers built highly accurate risk maps. One model, based on the presence of antibodies, achieved 79% accuracy and closely matched real infection data from 2024. 

The study also showed that the virus continues to circulate silently in endemic areas, emphasizing the importance of improving clinical and laboratory diagnosis. 

Transmitted by the Culicoides paraensis midge (also known as the biting midge), Oropouche Fever currently relies on symptom-based and epidemiological context for diagnosis. As the disease spreads geographically and remains hard to detect, the authors recommend systematically incorporating Oropouche Fever into national surveillance systems — especially in cases of febrile syndromes with nonspecific symptoms. 

This study offers a unique and comprehensive view of the Oropouche virus, highlighting the role of climate and providing accurate risk maps. The findings are crucial for helping health authorities anticipate and respond to future outbreaks, protecting vulnerable populations.