[Several principles for epidemiologic evaluation of individual regions of the Trans-Caucasian plains-piedmont natural focus of plague]. / O nekotorykh printsipakh épidemiologicheskoi otsenki otdel'nykh uchastkov Zakavkazskogo ravninno-predgornogo prirodnogo ochaga chumy.

The authors analyse many-year data concerning the epizootological study of seven landscape-geographical regions of the Eastern Transcaucasus differing by natural conditions and the enzootic intensity. Quantitative assessment of natural nidality determined by the level (norm) of many-year indices calculated for the years of 1955--1974 are presented for each region. Flea vectors were more numerous in localities of stable enzootic manifestation; also the numbers of Meriones erythrourus (carrier rodent) was more stable than in the regions of temporary occurrence of the causative agent and those free of plague. Many-year level of the flea (X. conformis) abundance index equal to one served as the threshold value determining the territory enzooticity.

[Effect of the economic activity of man on natural foci of plague]. / O vliianii khoziaistvennoi deiatel'nosti cheloveka na prirodnye ochagi chumy

Under the effect of human economic activity in the natural plague foci there occurred changes in the structures of local biocenoses. The extent and the direction of these changes were determined by the character and the scale of the economic activity. The final outcome of ploughing up, irrigation and supply with water of the vast areas is elimination of the focus or of its autonomic areas, but excessive exploitation of the desert pastures not infrequently leads to the opposite result. Large industrial construction and building of means of communications decreased the territories of the natural foci of plague only slightly, although no significant action was produced by them on the structure of biocenoses and the state of the foci.