Проблемы особо опасных инфекций (Dec 2015)
Factors that Predetermined Activation of Plague Epizooties in the Pre-Caspian Sandy Natural Focus in 2014
Abstract
In 2014, in the central coastal part of the Pre-Caspian sandy natural plague focus, activation of epizootic process in the complex rodent settlements occurred. Objective of the study was to identify the factors that predetermined the development of intensive and extensive plague epizooties. Utilized were operational data from the Astrakhan, Elista, and Dagestan plague control stations, and personal investigation records gathered in the focus. Consequently to the high baseline numbers of rodents and fleas, mild winter weather in 2013-2014 population density of the vectors and carriers of the infection significantly exceeded long-term average annual indexes in the following spring. Total abundance rates reached up to 31.1 specimens per a hectare, being lowered up to 17.8 by the fall. Stock of the main vector of plague, N. laeviceps flea, amounted to 350 and to 120 per a hectare in the spring and autumn, respectively. All in all, in the course of the three rolling seasons isolated were 56 Y. pestis cultures: 17 strains - from the rodents, and 39 - from the fleas. The overall epizootic area totaled to 2300 km2. Plague epizooties were registered in the zone of sustained natural focality within the bonds of the Ilmen-Pridelta, Primorsky, and Chernozemelsky landscape-epizootic regions in the administrative territory of the Limansky District in the Astrakhan Region, Lagansky and Chernozemelsky Regions of the Republic of Kalmykia, and Tarumovsky Region of the Republic of Dagestan. Results of monitoring over the epizootic manifestations and plague carrier and vector abundance dynamics provided the basis for scheduling and performance of anti-epidemic activities, as well as for forecasting of the epidemic situation development in the focus.
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