[Role of endoparasites of fleas of wild rodents in plague enzootia].

Laboratory studies of fleas for gregarines have established that it is the latter inhabiting the intestine and stomach of the fleas of wild rodents which are of much interest as protozoa, in whose organism, parasitic species of bacteria can survive. Penetration of plague bacteria into the endoplasm ofgregarines and their possible survival in the cysts may create an additional component in the chain of an epizootic process, which ensures its function, without involving the rodents at the nesting biocenotic level following the pattern: flea imagoes - nesting litter infected with gregarine spores, cysts - flea larvae - flea imagoes infected with cysts, with the plague pathogen emerging into a rodent population through the imago of blocked fleas.

[Current state of epidemiologic surveillance of natural foci of plague of North Caucasus].

Information on the epizootic situation in plague in the natural foci of North Caucasus and on the influence of a number of anthropogenic and natural factors on this situation is presented. The data given in this work indicate that under the conditions of the anthropogenic transformation of landscapes the character of the epizootic manifestations of plague is changed and new factors, capable of aggravating epidemiological situation, appear. In addition, some other factors must be considered, such as the insufficient financing of reliable field surveys at present, the impossibility of making reliable epizootological studies due to causes of the social character (armed conflicts), thus making it impossible to evaluate, with a sufficient degree of reliability, the real epizootic state of a number of territories and, therefore, the risk of human infection.

[Study of the natural sensitivity of Ixodes to insecticides].

The article deals with the results obtained in the study of the natural sensitivity of the nature populations of Ixodes ticks to 4 insecticides. As revealed in this study, the ticks are highly sensitive to commercial preparations in different phases of their development. The selective sensitivity of different species of ticks to these preparations is noted.

[Specific features of the parasitic system of Crimean haemorrhagic fever in Stavropol' region during epidemic season of 2000].

Information on Crimean haemorrhagic fever (CHF) in different climatic zones of the Krasnodar territory is presented. The epidemiological importance of some species of Ixodes ticks as vectors of the causative agent of CHF was shown. Ticks Hyalomma marginatum proved to be the main vector species: they constituted 75-100% of all ticks collected from cattle, reaching the peak of their abundance in May.