Reemergence of Oropouche Virus in the Americas and Risk for Spread in the United States and Its Territories, 2024

Abstract

Oropouche virus has recently caused outbreaks in South America and the Caribbean, expanding into areas to which the virus was previously not endemic. This geographic range expansion, in conjunction with the identification of vertical transmission and reports of deaths, has raised concerns about the broader threat this virus represents to the Americas. We review information on Oropouche virus, factors influencing its spread, transmission risk in the United States, and current status of public health response tools. On the basis of available data, the risk for sustained local transmission in the continental United States is considered low because of differences in vector ecology and in human-vector interactions when compared with Oropouche virus-endemic areas. However, more information is needed about the drivers for the current outbreak to clarify the risk for further expansion of this virus. Timely detection and control of this emerging pathogen should be prioritized to mitigate disease burden and stop its spread.

Keywords: Oropouche virus; United States; preparedness; response; vector-borne infections; viruses.

Figure 1

Possible biting midge and mosquito vectors of Oropouche virus found in United States in study of reemergence of Oropouche virus in the Americas, 2024. Possible vectors are presented in order of evidence for involvement in Oropouche virus transmission. A) Culicoides paraensis biting midge. Photo credit: “NACER355-12 Lateral”—BOLD:ABX5601 (compare Culicoides paraensis). Licensed under Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0). B) Culex quinquefasciatus mosquito. Photo credit: Centers for Disease Control and Prevention Public Health Image Library. C) Culicoides sonorensis biting midge. Photo credit: Dominic Rose.

Figure 2

Distribution of biting midge and mosquito vectors in the United States and select territories based on field observations and modelling in study of reemergence of Oropouche virus in the Americas, 2024. Possible vectors are presented in order of evidence for involvement in Oropouche virus transmission. A) Culicoides paraensis biting midge; B) Culex quinquefasciatus mosquito; C) Culicoides sonorensis biting midge. Presence of vectors in a jurisdiction does not imply uniform distribution throughout an entire geographic area. A zone exists where Cx. quinquefasciatus mosquitoes hybridize with other Culex species; this zone is not accounted for in the map because no vector competence studies for Oropouche virus for those species have been conducted. USVI, US Virgin Islands.