[Relations of the causative agents of plague and listeriosis during their simultaneous stay in the flea Citellophilus tesquorum at different environmental temperatures].

Experiments were carried out to determine the persistence of a plague microbe with varying praline labeling (isolated in the Central Caucasian mountain focus of plague in the fleas Citellophilus tesquorum of a mountain subspecies) in the contamination of the mixed culture of the plague microbe and Listeria. Inoculation of fleas with a suspension of a plague microbe and Listeriae demonstrates the manifest signs of antagonism between both species of microorganisms. This is evidenced by the reductions in the time of cultivation and in the number ofthese bacterial species in the experimental group fleas co-infected with Yersinia pestis and Listeria monocytogenes as compared with the control fleas (infected with monocultures of the causative agents of plague and listeriosis).

[Detection of plague microbe in the fleas by polymerase chain reaction by using magnetic immunosorbents].

The polymerase chain reaction (PCR) with and without pre-treatment of the samples of the fleas Citellophilus tesquorum with magnoimmunosorbents was used to detect the plague microbe in the samples containing 142, 168, 193 or more bacterial cells. PCR analysis reduced the time of tests of ectoparasites for plague to 6 hours. The use of a combination of PCR and magnoimmunosorbent simplified the most time-consuming and longest stage of isolation of plague microbial DNA from the suspensions of the fleas, which allows the time of a test to be reduced to 3 hours.

[Hydrological dangerous natural phenomena as cause of aggravation of an epidemiological situation].

Materials dealing with the specific features of the territory of Southern Russia, appearing as a consequence of natural, technogenic and some other factors, are presented. These materials indicate that, due to the high flood in summer of 2002, a real danger of a sharp aggravation of the epidemiological situation in acute enteric infections, as well as other infections, arose on a vast territory. As the result of the timely evaluation and analysis of changes in the factors of the natural and social environment, occurring as the consequence of the high flood, prophylactic measures were urgently carried out, thus making it possible to prevent the aggravation of the epidemiological situation.

[Situation of brucellosis in the regions of Stavropol Territory affected by the flood of 2002].

The emergency situation caused by inundations and high floods on the rivers in the affected regions exerts no direct influence on brucellosis morbidity among humans. Still the urgent evacuation of agricultural animals in connection with the natural calamity, their displacement and regrouping give grounds to prognosticate the deterioration of the epizootic situation in this infection in a number of regions of the territory where no sufficient veterinary surveillance has been ensured.

[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.