Exact determination of the eastern border of the European portion of the nosogeographic range of the hemorrhagic fever with renal syndrome

: Radioimmunoassay was used for examinations of 21,488 serum specimens from the population of 145 areas of 8 regions and 2 republics. The immune portion comprised 8.8% to the west of the assumed border and 2.7% to the east (t = 20.7). Active natural foci of the infection were found in individual territories located to the east of the assumed border (areas of Saratov Province to the north of the Irgiz River, trans-Ural areas of Bashkiria, southern taiga areas of Sverdlovsk, Tyumen, and northwestern Omsk Provinces). The extreme eastern points of the endemic area are Tevriz, Tary, and Znamenskoe Districts of Omsk Province. The areas of Siberian forest steppe, the steppe areas of western Siberia and those on the left bank of the Volga (Zavolzhye) are free from the infection foci. Natural foci of infection were found in the taiga part of the Komi ASSR, whereas they were absent in the forest tundra zone.