Abstract
We conducted a cross-sectional serosurvey for Oropouche virus (OROV) among residents of Amazonas State, Brazil, during 2015-2016. We detected OROV neutralizing antibodies in 85/814 (10.4%) participants; seroprevalence was higher in Manaus (49/440 [11.1%]) than in Coari (36/374 [9.6%]). Those findings suggest OROV circulation in Amazonas State before 2015.