Transovarial transmission is common in arthropods. Wild or domestic vertebrates usually are needed to maintain the cycle. Humans are usually dead-end hosts for all these viruses except phleboviruses. There is a secondary nosocomial spread of Crimean-Congo hemorrhagic fever. Hantaan virus cycles among rodents, probably by aerosol or fomite transmission from infected rodent urine.
Human infection is incidental.
Diagnosis Knowledge of the geographic site of exposure, season, and presence of arthropods leads to presumptive diagnosis in febrile cases. Control of the rodent host is important for hemorrhagic fever with renal syndrome. Bunyaviruses are responsible for a number of febrile diseases in humans and other vertebrates. They have either a rodent host or an arthropod vector and a vertebrate host. Bunyaviruses cause several diseases of human and domestic animals, including fever, hemorrhagic fever, renal failure, encephalitis, meningitis, blindness, and, in domestic animals, congenital defects.