Minimum of Great Gerbil Colonies ( <I>Rhombomys opimus</I> Liht., 1823., <I>Rodendtia</I>, <I>Crecetidae</I>) Necessary for Plague Epizooty Development in the Model

It is commonly known that under gerbil population depression habitable colonies are preserved as groups with varying number of colonies. In this connection, objectives of the study have turned out to be determination of minimum threshold number as regards habitable colonies where plague microbe circulation takes place. With the help of the computer model for plague epizootic process development determined is the fact that plague epizooty can last for a long while within the group of 25 habitable great gerbil colonies under certain conditions. This measure is reasonably close to the known factual evidence concerning a number and distribution of colonies at the time of major population depression. Therewith, one can conclude that plague microbe circulation can take place even in the course of major great gerbil population depression

Method of Biohazard Evaluation Regarding Internal and External Threats at the Level of Constituent Entity of the Russian Federation

Put forward is the method of evaluation of external and internal biosafety hazards at the level of constituent entity of the Russian Federation. It makes integration of the whole mass of medical and geographical information possible, and helps to stratify the territory depending upon the biohazard degree

Ecological-Epizootiological Differentiation of Natural Plague Foci

Plague foci differentiation is at the core of surveillance and forecasting of epizootic activity and hence achieving high effectiveness of prophylactic measures for prevention of human plague cases. Improvement of the plague foci differentiation taking into account recent data on their status and functioning is a relevant objective. The aim of the study was to differentiate natural plague foci according to the significance of ecology factors in the dynamics of epizootic activity. Materials and methods. Various models for forecasting epizootic activity of natural plague foci, based on the consistent statistical pattern recognition procedure were applied. 11 plague focal territories for which predictive models had ever been developed were surveyed. Results and discussion. The plague foci differ by impact of biotic and abiotic factors on epizootic activity. If epizootic activity depends on the biotic factors, forecasting can only be made on the basis of the data obtained directly during epizootiological surveillance. If epizootic activity depends on abiotic factors, such plague foci can be more depended on the global climate change. The put forward differentiation of focal areas allows for searching the common patterns of plague epizootic process in foci with different species of hosts and vectors, plague microbe variants and geographic setting, as well as for additional typification alongside the existing ones

Studies of ticks of the genus Dermacentor (Acari; Ixodidae) on the natural occurrence of tularemia pathogen in the conditions of the Central Pre-Caucasian region

The purpose of the research is the assessment of the Francisella tularensis occurrence in nature in ticks of the genus Dermacentor; understanding the physiological age in terms of tick infection with tularemia pathogen.Materials and methods. For the period from 2015 to 2019, we examined 8449 specimens of Dermacentor marginatus (916 pools), 8674 specimens of D. reticulatus (705 pools), and 109 specimens of D. niveus (40 pools) for tularemia infection. To assess the dependence of tularemia pathogen found in ticks of different physiological ages, we examined 2440 specimens of D. marginatus (360 pools), and 3349 specimens of D. reticulatus (412 pools) for the period from 2016 to 2019. Studies of ixodid ticks infected with tularemia pathogen were performed by the Natural Focal Infection Laboratory of the Stavropol Anti-Plague Institute. Pools of ixodid ticks were examined for the pathogen DNA of tularemia using reagent kits for identifying Francisella tularensis DNA by polymerase chain reaction with fluorescence hybridization of results recorded in real time.Results and discussion. The infection rate of the tularemia pathogen in ticks in the Central Pre-Caucasian region ranged from 0.044–1.127% in D. marginatus and 0.035–1.455% in D. reticulatus in different years. The greatest number of F. tularensis was isolated from the III physiological age ticks. For D. reticulatus ticks, no statistically significant dependence of the detected tularemia pathogen on physiological age was found

Infection Rate in the Population of Ticks <em>Hyalomma marginatum</em> in the Territory of the Crimean Hemorrhagic Fever (CHF) Natural Focus and Assessment of the Link with the CHF Incidence in the Stavropol Region

Objective of the study was to assess the infection rate in the population of the main CCHF virus vector Hyalomma marginatum and its impact on the CHF incidence in the Stavropol Region.Materials and methods. The data on spontaneous infection of H. marginatum ticks in the territory of the CHF natural focus in the Stavropol Region for the period 2012–2018 are presented. In total, more than 22.000 H. marginatum specimens pooled in 1546 samples were tested. The indication of CCHF virus was performed by PCR method using the reagent set for detecting RNA of the CCHF virus “AmplySens® CCHFV-FL” (produced by Central Research Institute of Epidemiology, Russia). To determine the individual infection rate in pools Beklemishev`s method was used. The data on CCHF incidence and amount of tick-bitten persons are taken from official statistics and Annual Epidemiological Report on CHF Incidence provided by the Rospotrebnadzor Administration in the Stavropol Region for the period of 2012–2018.Results and discussion. RNA of CCHF virus was detected in 161 (10.4 %) out of 1546 pooled ticks. The highest infection rate (20 %) was among nymphs. The infection rate for pooled males of H. marginatum was 11 % and for females – 8.5 %. Circulation of Crimean-Congo hemorrhagic fever virus is confirmed in major part of the Stavropol Region. The average infection rate among H. marginatum population was 1.54 % for the period of 2012–2018, ranging from 0.23 % in 2014 to 2.97 % in 2017. It is established that the level of infection rate among H. marginatum population does not affect the CHF incidence in the Stavropol Region. Probably it is not the number of infected ticks in the population that determines the CHF incidence rate but their abundance

Natural Focal Viral Fevers in the South of the European Part of Russia. Hemorrhagic Fever with Renal syndrome

Objective of the study was to determine the modem epizootic and epidemic peculiarities of hemorrhagic fever with renal syndrome in the south of the European part of Russia. Materials and methods. Data of statistical documentation (epidemiological survey of the infectious disease focus, annual summary reports dated 2009-2018) and epizootic monitoring data submitted by the Rospotrebnadzor Administrations and the Centers of Hygiene and Epidemiology in the constituent entities of the Southern and the North Caucasian Federal Districts were used. Descriptive, analytical methods and retrospective epidemiological analysis were applied. Results and discussion. The circulation of hantavirus in the Volgograd and Astrakhan Regions, Stavropol and Krasnodar Territories, Republics of Adygeya, Kalmykia and Crimea was confirmed. However, two geographically and genetically isolated groups of hantaviruses circulating in the Volgograd Region and in the mountain-foothill zone of the Krasnodar Territory and the Republic of Adygeya were the most epidemiologically significant. Over the period of 2009-2018, 152 HFRS cases with annual fluctuations from 4 to 25 cases were registered. Almost all patients lived in the Volgograd Region (44 cases), where the incidence is caused by the HFRS-Puumala virus, or in the Krasnodar Territory (98 cases), where the HFRS Hantavirus Dobrava-Ap circulates. In HFRS patients with the HFRS-Dobrava-Ap virus severe clinical forms were noted at twice the rate, a fatal outcome in one patient with HFRS-Puumala was recorded. The correct preliminary diagnosis was made for 56.3 per cent of patients in the Volgograd Region and only for 31.7 per cent of patients in the Krasnodar Territory and in the Republic of Adygeya. There are different types of natural HFRS foci in the European south of Russia, they vary by the type of hosts and hantaviruses circulating in them - Puumala, Dobrava, Tula, and Dobrava-Ap. Natural foci where of HFRS-PUU and HFRS-DOB-Ap viruses circulate have high epidemic potential. Severe forms of the HFRS are more often observed in patients with the HFRS-DOB-Ap virus

Исследования клещей рода Dermacentor (Acari; Ixodidae) на естественную встречаемость возбудителя туляремии в условиях Центрального Предкавказья

The purpose of the research is the assessment of the Francisella tularensis occurrence in nature in ticks of the genus Dermacentor; understanding the physiological age in terms of tick infection with tularemia pathogen.Materials and methods. For the period from 2015 to 2019, we examined 8449 specimens of Dermacentor marginatus (916 pools), 8674 specimens of D. reticulatus (705 pools), and 109 specimens of D. niveus (40 pools) for tularemia infection. To assess the dependence of tularemia pathogen found in ticks of different physiological ages, we examined 2440 specimens of D. marginatus (360 pools), and 3349 specimens of D. reticulatus (412 pools) for the period from 2016 to 2019. Studies of ixodid ticks infected with tularemia pathogen were performed by the Natural Focal Infection Laboratory of the Stavropol Anti-Plague Institute. Pools of ixodid ticks were examined for the pathogen DNA of tularemia using reagent kits for identifying Francisella tularensis DNA by polymerase chain reaction with fluorescence hybridization of results recorded in real time.Results and discussion. The infection rate of the tularemia pathogen in ticks in the Central Pre-Caucasian region ranged from 0.044–1.127% in D. marginatus and 0.035–1.455% in D. reticulatus in different years. The greatest number of F. tularensis was isolated from the III physiological age ticks. For D. reticulatus ticks, no statistically significant dependence of the detected tularemia pathogen on physiological age was found.Цель исследований: оценка естественной встречаемости Francisella tularensis в клещах рода Dermacentor; выяснение связи физиологического возраста и зараженности клещей возбудителем туляремии.Материалы и методы. За период с 2015 по 2019 гг. на зараженность туляремией исследовано 8449 экз. Dermacentor marginatus (916 пулов), 8674 экз. D. reticulatus (705 пулов) и 109 экз. D. niveus (40 пулов). Для оценки зависимости обнаружения возбудителя туляремии в клещах разного физиологического возраста нами за период с 2016 по 2019 гг. исследовано 2440 экз. D. marginatus (360 пулов) и 3349 экз. D. reticulatus (412 пулов). Исследования на зараженность иксодовых клещей возбудителем туляремии проводили в лаборатории природно-очаговых инфекций Ставропольского противочумного института. Пулы иксодовых клещей исследовали на наличие ДНК возбудителя туляремии с использованием наборов реагентов для выявления ДНК Francisella tularensis методом полимеразной цепной реакции с гибридизационно-флуоресцентным учетом результатов в режиме реального времени.Результаты и обсуждение. Зараженность клещей возбудителем туляремии в Центральном Предкавказье в разные годы колеблется в пределах 0,044–1,127% у D. marginatus и 0,035–1,455% у D. reticulatus. В наибольшем количестве F. tularensis выделяли от клещей III физиологического возраста. Для клещей D. reticulatus не выявлено статистически значимой зависимости обнаружения возбудителя туляремии от физиологического возраста

Peculiarities of Immunological Structure Formation in Plague Carriers of the Central-Caucasian High-Mountain Natural Plague Focus

Objective of the study is to analyze immunological structure of the mountain souslik, habitant in various zones of natural focality in the Central-Caucasian natural plague focus.Materials and methods. The data on serological investigations conducted on the mountain souslik, within the periods of 1974–1988 and 2001–2004 have been obtained from FGHI “Kabardino-Balkaria Plague Control Station” of the Rospotrebnadzor. Applying passive hemagglutination test and indirect hemagglutination test, with the help of Excel Microsoft Office 2010, evaluated have been 63147 blood survey results.Conclusions. It is established that the highest ratio of the souslik with low antibody titer in blood, which characterizes initial contact with plague infection, is observed at the peak of epizootic activity. In the mountain steppe of the eastern focal part, the apex coincides with June, in the western part, as well as in the Alpine and Subalpine zones of the eastern one – with August. Animals with high antibody titers, i.e. secondarily infected, emerge in vast numbers at the peak of mountain souslik lethality. In the mountain steppe this period falls upon June, i.e. simultaneously with the peak of epizootic activity. In the western part lethality apex is also observed in June, but maximum epizootic activity takes place in August. In Alpine and Subalpine zones of the eastern focal part, peaks of epizootic activity and lethality among the souslik populations concur and fall upon August. Isolation of plague microbe cultures alongside with positive serological tests is reasonably more often observed in the mountain steppe of the river Baksan, than in other areas of natural focality

Forecasting of epizootic Activity of the Central Caucasian natural High-Mountain Plague Focus

Central-Caucasian natural plague focus was permanently epizootically active since its discovering in 1971 till 2007. Inter-epizootic period has been in progress since 2008. It was not possible to isolate agent strains from field material. Therefore a forecast for focus activation is a relevant task, especially against the background of registered plague cases in humans in 2014–2016. Objective of the study was to create a forecasting model for quantitative prediction of possible activation or maintenance of inter-epizootic period. Materials and methods. We used archival data of Kabardino-Balkar Plague Control Station: journals of rodents’ autopsy, annual reports on epizootiological surveillance, meteorological data from meteostation “Kislovodsk” over the period of 1989–2017, and our epidemiological data for the period 2010 to 2017. We applied Spearman nonparametric correlation analysis, regression analysis, including principal component method, quarterly analysis, and inhomogeneous sequential pattern recognition procedures for statistical processing. Results and discussion. We have designed statistical model which provides for forecasting of plague focus epizootic activity proactively, a year in advance and 99 % probability or higher. The model was tested on retrospective data over the course of 7 years. All predictions were correct. The operational forecasts from 2015 to 2017 proved right too. However there is a possibility of fast changes in the ecology system conditions of the Central-Caucasian natural plague focus because of the global warming. Thereby the forecasting model will be annually checked for informative value of the predictors and, if necessary, adjusted accordingly

Provision of Epidemiological Surveillance and Prophylaxis of Zika Fever in the Russian Federation

Epidemic outspread of Zika fever has given WHO authority to declare emergency situation in the sphere of international healthcare. Major risks for the Russian Federation are associated with the import of the disease by persons, infected in epidemiologically hazardous territory, or import of Zika virus vectors by transport means of international traffic. In this context, developed and normatively regimented is the complex of measures aimed at prevention of Zika virus disease, comprising activities to control import of the infection from enzootic territories, monitoring over the vectors of virus, Ae. aegypti and Ae. albopictus , and procedure for disinfection operations. Developed and introduced into practice is a home-made preparation for laboratory diagnostics and detection of Zika virus RNA using PCR. The article covers the issue of possible dissemination of the vectors in southern regions of Russia in view of climate warming. It is concluded that nowadays probability of local Zika virus transmission in “human-mosquito” cycle is extremely low and no complications of epidemiological situation on arboviral Ae. aegypti- and Ae. albopictus- borne infections are predicted