Recent seroprevalence studies in animals detected Rocio virus in regions of Brazil, indicating risk for re-emergence of this pathogen. We identified Rocio virus RNA in samples from 2 human patients for whom dengue fever was clinically suspected but ruled out by laboratory findings. Testing for infrequent flavivirus infections should expedite diagnoses.
Keywords: Brazil; NS5; Rocio virus; SPH 34675; dengue; emerging neurotropic flavivirus; molecular diagnostics; vector-borne infections; viruses.