Oropouche fever (OF), caused by the Oropouche virus (OROV), is an emerging zoonotic arboviral disease with two transmission cycles: an urban cycle involving Culicoides paraensis bites and a more complex sylvatic cycle involving various arthropods and reservoir hosts. First identified in Trinidad and Tobago in the 1950s, OROV was isolated in Brazil in 1960 and has since spread to the Amazon region and parts of Central and South America. Environmental changes and human mobility contribute to its spread. OF presents with symptoms similar to dengue and chikungunya, including fever, headache, arthralgia, and rash, making diagnosis challenging without laboratory confirmation. Treatment is supportive, emphasizing prevention and control. The recent confirmation of OF in Rio de Janeiro and a significant increase in cases in Amazonas highlight the virus's expansion beyond traditional areas. The concurrent dengue epidemic and limited diagnostic capacity suggest underdiagnosis of OF, posing a challenge to the health system. This situation requires coordinated efforts to develop testing protocols, investigate travel histories, and implement prevention measures. The authors contributed equally to the manuscript and declare no conflicts of interest. Funding was not provided.Oropouche fever (OF), caused by the Oropouche virus (OROV), is an emerging zoonotic arboviral disease with two transmission cycles: an urban cycle involving Culicoides paraensis bites and a more complex sylvatic cycle involving various arthropods and reservoir hosts. First identified in Trinidad and Tobago in the 1950s, OROV was isolated in Brazil in 1960 and has since spread to the Amazon region and parts of Central and South America. Environmental changes and human mobility contribute to its spread. OF presents with symptoms similar to dengue and chikungunya, including fever, headache, arthralgia, and rash, making diagnosis challenging without laboratory confirmation. Treatment is supportive, emphasizing prevention and control. The recent confirmation of OF in Rio de Janeiro and a significant increase in cases in Amazonas highlight the virus's expansion beyond traditional areas. The concurrent dengue epidemic and limited diagnostic capacity suggest underdiagnosis of OF, posing a challenge to the health system. This situation requires coordinated efforts to develop testing protocols, investigate travel histories, and implement prevention measures. The authors contributed equally to the manuscript and declare no conflicts of interest. Funding was not provided.