Characteristics of endemic foci of hemorrhagic fever with renal syndrome in different regions of the USSR.

: Clinical, epizootological, and laboratory data for 9 endemic foci of hemorrhagic fever with renal syndrome (HFRS) were compared. The analysis covered 5120 cases of HFRS. It was established that in the foci, where the leading role is played by field mouse and Japanese field mouse, HFRS is caused by the 1st serotype of HFRS virus, and the clinical course of the disease is quite severe. In the natural foci with the predominance of redbacked vole, the 2nd serotype of the virus circulates and the disease is of moderate severity or mild. In each individual case, however, both serotypes of the virus may produce both mild and severe diseases.