Presented are the results of ecological and epizootiological surveillance of the territory of the Saratov region, which was carried out in autumn of 2010. The surveillance was aimed at detection of West Nile (WN) virus circulation and premises for WN Fever natural focus formation. It is demonstrated that in 2010 WN virus circulation took place in damp biotopes of the Saratov region territory, and that common species of small mammals were involved in it. Presented are the results of analysis of the WN virus role in the infectious pathology in the territory of the Saratov region.

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The role of the background species of mouse-like rodents in the preservation of arboviral infections in the semi-desert zone of Saratov Zavolzhie was studied. Determined were the indices of their number in the near-water and anthropogenic biotopes, and arboviral infection rate in some species. Substantiated was high potential epidemic danger of the intrazonal biotopes as centers of formation of associated natural foci of arboviral infections.