Long-term analysis of data on the isolation of Yersinia pestis cultures from rodents during epizootological examinations of natural foci in Muyun-Kum and eastern Kizil-Kum.

Results are presented of a long-term examination and evaluation of data on the microbiological procedures of isolating Yersinia pestis cultures from wild mammals and their association animal plague pathogenesis as suggested by investigations in the Muyun-Kum autonomous plague focus and the Eastern Kizil-Kum mesofocus. 1772 Yersinia pestits cultures were isolated largely from Rhombomys opimus as the principle host over 23 years. The authors determined the frequency of pathological alterations in the body organs of infected animals, Rhombomys opimus featuring alterations more often than Meriones sp. Also determined was the rate of Y. pestis isolation from different organs. The authors assessed the validity of examining rodents by the method of direct inoculation of organ microflora on agar plates and by the biological assay. Direct inoculation into agar was shown to yield superior results. The reasons for occasional culture failures are analyzed in group bioassays as well as the advantages of individual bioassays. The significance of collecting and examining dead animals found in the steppe are evaluated as well as focus-specific differences between R. opimus and Meriones sp. with respect to the above parameters. Recommendations are given on assaying animals for plague infection.