INFLUENCE OF RODENTICIDE ON NATURAL FOCUS OF FIELD FEVER - PRELIMINARY-REPORT

The effect of a repeated deratization by a zinc phosphide preparation realized 10-12 years ago was studied in a natural focus of leptospiros is grippotyphosa and tularemia in 1991. The changes in percentual occu rrence of individual species of small rodents (185 animals checked) as well as in their infestation by leptospires were compared with the an alogical data prior to and immediately after deratization. Leptospiros is in animals trapped before or during deratization was not checked. R enal tissue cultivation proved that the positivity proportion of Micro tus arvalis, the main host of L. gippotyphosa, was high (about 20 %) b oth immediately after the intervention, i. e. between 1981 - 1984 as w ell as later in 1991. A considerable reduction of this animal species from 39.1 % to 2.7 % caused a significant reduction of the field fever reservoirs. On the contrary, the percentual occurrence of another L. grippotyphosa host Cl. glareolus increased from 21.9 % to 57.3 %, whil e its positivity for leptospires decreased from the original 3.5 % in the years 1981 - 1984 to the zero value in 1991. This animal species s hows evidently no tendency to take over the role of the L. grippotypho sa reservoir. On the basis of this investigation, gradual elimination of the field fever natural focus may be assumed in future.