Integrated surveillance for Oropouche Virus: Molecular evidence of potential urban vectors during an outbreak in the Brazilian Amazon

Abstract

The Oropouche Virus (OROV) has Culicoides paraensis as its main vector in the urban cycle. Diagnoses of acute febrile cases and entomological collections were performed between January and April 2024 in the urban setting of Porto Velho, a city located in the western Brazilian Amazon. A total of 904 human samples were evaluated using RT-qPCR, of which 328 were positive for OROV. In addition, 3,950 insects were captured and Culex quinquefasciatus was the most abundant and predominant species. Seven mosquito samples showed amplification for OROV from pools of Cx. quinquefasciatus, Limatus durhamii and Aedes albopictus. Due to the first record of OROV in the two latter species, our findings can support new hypotheses about potential or bridge vectors. In turn, the high density of Cx. quinquefasciatus reinforces the supposition of this species as the main urban vector in the Amazon in the absence of C. paraensis. Complementary studies of vector competence and capacity are necessary for confirmation.

Keywords: Aedes albopictus; Culex quinquefasciatus; Limatus durhamii; Oropouche fever; Vertical transmission.