[The topographic zoning of natural HFRS foci in Russia].

Using large selections the unified system of landscape districting of HFRS natural foci with allocation of special geo-botanical provinces has been developed. This permits to avoid various deviations were found to appear during association of epizootiological and epidemiological indexes of separate towns and rural districts when estimating regional parameters. Adequacy of the offered system in confirmed by five-fold increase of the correlation between HFRS epizootiological parameters and antibody prevalence rate in humans. The steady maximum of all parameters was registered in the province situated in broad-leafed oak-line forests. Minimal values are found to correspond to one located in forest-steppe (with birch and asp forests) which poor fodder potential for rodents is well known. Other provinces between these ones are characterized by consecutive decrease of all index values according to the landscape type. According to estimated natural activity rate all the provinces are divided to three groups. The first one (antibody prevalence rate is above 5%) unites the high activity HFRS natural foci. Their common geographical location is on the territories with highest rodent population rates. The second group (antibody prevalence rate--2-4%) includes HFRS foci with average activity, and the third one (antibody prevalence rate is below 2%)--with low activity. The most of the last group provinces are situated on periphery or behind the bank vole living area.