kestaga spiraalne üheahelaline RNA viirus, any of a family (Bunyaviridae) of usually spherical or pleomorphic single-stranded RNA viruses usually transmitted by the bite of an arthropod (such as a mosquito) or in the bodily secretions of rodents and including the hantaviruses and the causative agents of Rift Valley fever, sandfly fever, and some forms of encephalitis and hemorrhagic fever, any member of the genus Bunyavirus or family Bunyaviridae of enveloped viruses with a three-segmented single-stranded RNA genome, most of which are arthropod-borne pathogens of humans and other mammals, typically causing fever or encephalitis