In the rodent host HTN causes a chronic infection that does not appear to result in disease. HFRS is an acute febrile illness that was first recognized in the western world after a 1951 outbreak among U.S. troops stationed in Korea. This is followed by flushing, then petechiae. Thrombocytopenia, neutrophilia with left shift, atypical lymphocytes and hemoconcentration are common. There is acute renal failure, but the precise pathophysiologic lesion producing renal failure is uncertain.
Mortality is usually from shock or hemorrhage.
Isolation attempts had been unsuccessful. Despite extensive study, no arthropod vector has been implicated in the transmission of any hantavirus. Infected rodents appear to be persistently infected and viruric. HTN seroprevalence among mice in endemic areas, as assessed by seroreactivity to culture-adapted Hantaan virus, fluctuates in a biphasic manner. The incidence of HFRS among humans follows a similar trend, but the curve slightly trails the seroprevalence curve among A. agrarius populations.