Plague Foci Research Articles

Pasteurella multocida strains of a novel capsular serotype and lethal to Marmota himalayana on Qinghai-Tibet plateau in China

Pasteurella multocida is a zoonotic pathogen causing serious diseases in humans and animals. Here, we report P. multocida from wildlife on China's Qinghai-Tibet plateau with a novel capsular serotype, forming a single branch on the core-genome phylogenetic tree: four strains isolated from dead Himalayan marmot (Marmota himalayana) and one genome assembled from metagenomic sequencing of a dead Woolly hare (Lepus oiostolus). Four of the strains were identified as subspecies multocida and one was septica. The mouse model showed that the challenge strain killed mice within 24 h at an infectious dose of less than 300 bacteria. The short disease course is comparable to septicemic plague: the host has died before more severe pathological changes could take place. Though pathological changes were relatively mild, cytokine storm was obvious with a significant rise of IL-12p70, IL-6, TNF-αand IL-10 (P < 0.05). Our findings suggested P. multocida is a lethal pathogen for wildlife on Qinghai-Tibet plateau, in addition to Yersinia pestis. Individuals residing within the M. himalayana plague focus are at risk for P. multocida infection, and public health warnings are necessitated.

Анализ биотопической приуроченности мышевидных грызунов на территориях природных очагов чумы и туляремии Республики Дагестан

Mouse-like rodents in natural plague foci occupy an important place as potential reservoirs of the causative agent of this dangerous disease, acting in some cases as the main or secondary carriers of the pathogen. On the territory of the Republic of Dagestan, characterized by a variety of natural conditions – from flat dry deserts to foothills and highlands, with an abundance of anthropogenic biotopes, this group of small mammals is quite widely represented in terms of species diversity. This work is based on the analysis of the results of long-term epizootological monitoring over the period 2010–2021 carried out in three natural foci of plague: Dagestan plain-foothill, Caspian sandy and East Caucasian high-mountain and tularemia (Plain-foothill steppe, Terek-Kuma floodplain-marsh and Highmountain foothill-mountain-stream). To assess the selectivity of a species in choosing a biotope, the authors used the degree of biotopic confinement Fij (Y.A. Pesenko, 1982). All calculations were carried in Microsoft Office Excel. In these calculations, eurytopic species dominated, which can participate in the epizootic process during periods of activation of foci, contributing to the spread of infectious agents. It was revealed that most species are confined to moist biotopes of river banks and canals, which can be habitats for small mammals during periods of population depression. In this biotope, it is necessary to conduct a more thorough epizootological examination for tularemia and other particularly dangerous infections. The proposed method will make it possible to streamline the control of mouse-like rodents and optimize the work of epizootological examination on the territory of the Republic of Dagestan.

ГАМАЗОВЫЕ КЛЕЩИ (GAMASINA) ГНЕЗД ОБЫКНОВЕННОЙ ПОЛЕВКИ ПРИСЕВАНСКОГО МЕЗООЧАГА ЗАКАВКАЗСКОГО ВЫСОКОГОРНОГО ПРИРОДНОГО ОЧАГА ЧУМЫ

The paper highlights new data on the species composition of gamasid ticks living in the nests of the common vole of the Prisevan meso-foci of the Transcaucasian high-mountain natural plague foci of the Republic of Armenia. As a result of the research conducted in the studied territory, the fauna of gamasid ticks is represented by nine species, including two species that were not previously found in the nests of the common vole. Key words: gamasid ticks, common vole, parasitic arthropods, Prisevan meso-foci, Transcaucasian high-mountain natural plague foci.

Молекулярно-генетический анализ штаммов Yersinia pestis, выделенных в различные эпизоотические периоды на территории Урало-Эмбенского пустынного природного очага чумы в ХХ веке

We performed a molecular genetic analysis of Yersinia pestis strains isolated in the Ural-Embensky desert natural plague focus area in the twentieth century. We studied 24 strains of Y. pestis isolated on this territory since 1945 to1991, as well as 21 strains of Y. pestis from adjacent territories. All of the strains studied from the Ural-Embensky natural focus of plague belonged to the highly virulent and epidemically significant medieval biovar of the main subspecies Y. pestis. According to the results of the WG-SNP analysis and subsequent phylogenetic reconstruction based on 1353 SNPs, the maximum likelihood method (Maximum Likelihood, GTR model) revealed 6 key phylopopulations, which included strains isolated during different periods of epidemic and epizootic activity in the study area. It has been established that there were three waves of spread of the 2.MED1 branch of the medieval biovar to the territory of Ural-Embensky desert natural plague focus. Strains isolated before 1945 belong to the first wave of spread of the 2.MED1 branch to the territory of the Northern Caspian Region. The second wave is considered to be the 1968–1974 strains. They have close genetic similarities with strains from the Mangyshlak (1978) and Ustyurt desert plague foci (1962 and 1975). The third wave includes strains isolated after 1966. They are genetically close to the strains from the North Aral foci (1945). The data obtained will be used for molecular-genetic detailing of the certification of foci in which this highly virulent medieval Y. pestis biovar circulates. They are important for determining the patterns of spatiotemporal distribution of highly virulent strains of the 2.MED1 branch of the medieval biovar in the 20th century and for long-term forecasting of the epizootic activity of plague foci in the North-Eastern Caspian region in the current 21st century.

Assessing the effectiveness of intervention to prevent plague through community and animal-based survey.

Bubonic plague, transmitted by infected flea bites, is the most common form of plague and, left untreated, can progress to the pneumonic form, which is highly contagious. Surveillance focusing on reservoir and vector is considered to be the main approach to prevent plague. Common rodent control methods include the use of rodenticide and snap traps but, in a plague context, the dispersal of fleas from killed animals may pose a serious health threat. Therefore, there is a need for strategies which address reservoir and vector control. The aim of this study was to assess the effects of combination of reservoir and vector control through community-based surveillance. Activities were implemented by local previously trained community agents in two active plague foci in Madagascar. Kartman bait stations containing rodenticide and insecticide were placed indoors while live traps were set outdoors. Small mammals were identified and killed with their fleas. Effectiveness of control measures was evaluated by comparison of plague incidence two years before and after intervention using data on reported human cases of plague from the Central Laboratory of Plague. A total of 4,302 small mammals were captured, with the predominance of the black rat Rattus rattus. Our results found a reduction in plague incidence in the treated site for at least two years after treatment. Community-based interventions played an important role in reducing contact between humans-rodents-fleas. Our study confirms the importance of animal surveillance during the low plague transmission season. The combination of reservoir and vector control with community involvement may be effective at reducing the risks of plague spillover to humans. The strategy of using Kartman bait stations indoors with live traps outdoors can be used to refine proactive plague prevention, however, due to the potential development of resistance to pesticides in flea and rat populations, overuse should be considered.

Theriological Investigations in Plague Foci on the Territory of Russia and Neighboring Countries

Theriological Investigations in Plague Foci on the Territory of Russia and Neighboring Countries

Population dynamics of plague vector fleas in an endemic focus: implications for plague surveillance.

Plague is a zoonotic vector-borne disease caused by the bacterium Yersinia pestis. In Madagascar, it persists in identified foci, where it is a threat to public health generally from September to April. A more complete understanding of how the disease persists could guide control strategies. Fleas are the main vector for transmission between small mammal hosts and humans, and fleas likely play a role in the maintenance of plague. This study characterized the dynamics of flea populations in plague foci alongside the occurrence of human cases. From 2018 to 2020, small mammals were trapped at sites in the central Highlands of Madagascar. A total of 2,762 small mammals were captured and 5,295 fleas were collected. The analysis examines 2 plague vector species in Madagascar (Synopsyllus fonquerniei and Xenopsylla cheopis). Generalized linear models were used to relate flea abundance to abiotic factors, with adjustments for trap location and flea species. We observed significant effects of abiotic factors on the abundance, intensity, and infestation rate by the outdoor-associated flea species, S. fonquerniei, but weak seasonality for the indoor-associated flea species, X. cheopis. A difference in the timing of peak abundance was observed between the 2 flea species during and outside the plague season. While the present study did not identify a clear link between flea population dynamics and plague maintenance, as only one collected X. cheopis was infected, the results presented herein can be used by local health authorities to improve monitoring and control strategies of plague vector fleas in Madagascar.

The surveillance of plague among rodents and dogs in Western Iran.

The causative agent of plague, Yersinia pestis, is maintained in nature via a flea-rodent cycle. Western Iran is an old focus for plague, and recent data indicate that rodents and dogs in this region have serological evidence of Y. pestis infection. The purpose of this study was to conduct a large-scale investigation of Y. pestis infection in shepherd dogs, rodents, and their fleas in old foci for plague in Western Iran. This study was conducted in Hamadan province from 2014 to 2020. Rodents and fleas were collected from various locations throughout this region. Y. pestis was investigated in rodent spleen samples and fleas using culture, serology, and real-time PCR methods. Additionally, sera samples were collected from carnivores and hares in this region, and the IgG antibody against the Y. pestis F1 antigen was assessed using an ELISA. In this study, 927 rodents were captured, with Meriones spp. (91.8%) and Microtus qazvinensis (2.6%) being the most prevalent. A total of 6051 fleas were collected from rodents and carnivores, most of which were isolated from Meriones persicus. None of the rodents or fleas examined tested positive for Y. pestis using real-time PCR and culture methods. Meanwhile, IgG antibodies were detected in 0.32% of rodents. All serologically positive rodents belonged to M. persicus. Furthermore, none of the sera from the 138 carnivores (129 sheepdogs, five Vulpes vulpes, four Canis aureus), and nine hares tested positive in the ELISA test. This primary survey of rodent reservoirs shows serological evidence of Y. pestis infection. Western Iran is an endemic plague focus, and as such, it requires ongoing surveillance.

Mapping Plague Risk Using Super Species Distribution Models and Forecasts for Rodents in the Zhambyl Region, Kazakhstan.

One of the most extensive natural plague centers, or foci, is located in Central Asia, in particular, the Zhambyl region in Southern Kazakhstan. Here, we conducted plague surveillance from 2000 to 2020 in the Zhambyl region in Kazakhstan and confirmed 3,072 cases of infected wild animals. We used Species Distribution Modeling by employing MaxEnt, and identified that the natural plague foci are primarily located in the Moiynqum, Betpaqdala, and Tauqum Deserts. The Zhambyl region's central part, including the Moiynqum and Sarysu districts, has a high potential risk of plague outbreak for the rural towns and villages. Since the phenomenon of climate change has been identified as a determinant that affects the rodent populations, thereby elevating the likelihood of an outbreak of plague, we investigated the potential dissemination routes of the disease under the changing climate conditions, thus creating Species Distribution Forecasts for the rodent species in southern part of Kazakhstan for the year 2100. By 2100, in case of increasing temperatures, the range of host species is likely to expand, leading to a higher risk of plague outbreaks. The highest risk of disease transmission can be expected at the outer limits of the modeled total distribution range, where infection rates are high, but antibody presence is low, making many species susceptible to the pathogen. To mitigate the risk of a potential plague outbreak, it is necessary to implement appropriate sanitary-epidemiological measures and climate mitigation policies.

Complete mitochondrial genome of Ctenophthalmus quadratus and Stenischia humilis in China provides insights into fleas phylogeny.

Fleas (Order Siphonaptera) are common blood-feeding ectoparasites, which have important economic significance. Limited mitochondrial genome information has impeded the study of flea biology, population genetics and phylogenetics. The Ctenophthalmus quadratus and Stenischia humilis complete mt genomes are described in this study. The samples were collected from Jianchuan, Yunnan plague foci, China. The mt genomes of C. quadratus and S. humilis were 15,938 bp and 15,617 bp, respectively. The gene arrangement of mt genome was consistent with that of other fleas, which include 22 tRNA genes, 13 protein-coding genes, and two rRNA genes, with a total of 37 genes. The relationship between C. quadratus and S. humilis in fleas was inferred by phylogenetic analysis of mt genome sequence datasets. Phylogenetic analyzes showed that the C. quadratus and S. humilis belonged to different species in the same family, and were closely related to Hystrichopsylla weida qinlingensis in the same family; and revealed that the family Hystrichopsyllidae is paraphyletic, supporting the monophyly of the order Siphonaptera. This study decodes the complete mt genomes of the C. quadratus and S. humilis for the first time. The results demonstrate that the C. quadratus and S. humilis are distinct species, and fleas are monophyletic. Analysis of mt genome provides novel molecular data for further studying the phylogeny and evolution of fleas.

Genomic diversity of Yersinia pestis from Yunnan Province, China, implies a potential common ancestor as the source of two plague epidemics

Plague, caused by Yersinia pestis, is a zoonotic disease that can reemerge and cause outbreaks following decades of latency in natural plague foci. However, the genetic diversity and spread pattern of Y. pestis during these epidemic-silent cycles remain unclear. In this study, we analyze 356 Y. pestis genomes isolated between 1952 and 2016 in the Yunnan Rattus tanezumi plague focus, China, covering two epidemic-silent cycles. Through high-resolution genomic epidemiological analysis, we find that 96% of Y. pestis genomes belong to phylogroup 1.ORI2 and are subdivided into two sister clades (Sublineage1 and Sublineage2) characterized by different temporal-spatial distributions and genetic diversity. Most of the Sublineage1 strains are isolated from the first epidemic-silent cycle, while Sublineage2 strains are predominantly from the second cycle and revealing a west to east spread. The two sister clades evolved in parallel from a common ancestor and independently lead to two separate epidemics, confirming that the pathogen responsible for the second epidemic following the silent interval is not a descendant of the causative strain of the first epidemic. Our results provide a mechanism for defining epidemic-silent cycles in natural plague foci, which is valuable in the prevention and control of future plague outbreaks.

The complex genomic diversity of Yersinia pestis on the long-term plague foci in Qinghai-Tibet plateau.

Plague is a typical natural focus disease that circulates in different ecology of vectors and reservoir hosts. We conducted genomic population and phylogenetic analyses of the Yersinia pestis collected from the 12 natural plague foci in China with more than 20 kinds of hosts and vectors. Different ecological landscapes with specific hosts, vectors, and habitat which shape various niches for Y. pestis. The phylogeographic diversity of Y. pestis in different kinds plague foci in China showed host niches adaptation. Most natural plague foci strains are region-and focus-specific, with one predominant subpopulation; but the isolates from the Qinghai-Tibet plateau harbor a higher genetic diversity than other foci. The Y. pestis from Marmota himalayana plague foci are defined as the ancestors of different populations at the root of the evolutionary tree, suggesting several different evolutionary paths to other foci. It has the largest pan-genome and widest SNP distances with most accessory genes enriched in mobilome functions (prophages, transposons). Geological barriers play an important role in the maintenance of local Y. pestis species and block the introduction of non-native strains. This study provides new insights into the control of plague outbreaks and epidemics, deepened the understanding of the evolutionary history of MHPF (M. himalayana plague focus) in China. The population structure and identify clades among different natural foci of China renewed the space cognition of the plague.

Natural foci of plague in Kazakhstan in the space-time continuum

The relevance of the problem of the stated topic lies in the fact that the causative agent of the plague infection demonstrates high survival while maintaining high virulence in the territories, which are enzootic in terms of the plague. The study aimed to investigate the geographic distribution and genetic diversity of the plague pathogen in endemic regions through molecular genetic research. The work included the results of laboratory studies of 3058 samples, including soil – 1154, burrow substrates – 549, the contents of the feeding chamber – 349, bone remains – 18, biological objects – 988 samples of sera and suspensions from carriers and vectors of plague infection collected from 14 autonomous plague foci of Kazakhstan for the period 2021–2022. The leading method in the study was a laboratory experiment, thanks to which, using a new advanced technology on a microbiological analyser VITEK 2 COMPACT 30, it was possible to study pathogenic and non-pathogenic strains of the genus Yersinia isolated during field experiment. As a result of experimental work, it was shown that during a long inter-epizootic period, the plague pathogen can persist in the soil in symbiosis with soil microorganisms, and in this area, it chooses soil with a low-quality index of 10 points, where soils with a low total microbial number and species landscape prevail.

Effect of &lt;i&gt;Yersinia pestis&lt;/i&gt; on the Soil Nematodes &lt;i&gt;Panagrolaimus&lt;/i&gt; sp. from the Gorno-Altai High-Mountain Focus of Plague

The aimof the work was to study interaction ofYersinia pestiswith soil nematodes isolated on the territory of the Gorno-Altai high-mountain plague focus.Materials and methods. We used the fluorescentY. pestisstrain KM2083, a derivative of the natural strain of the 4.ANT phylogenetic line, the antique biovar of the main subspecies, and a nematode culture isolated in the same area of the Gorno-Altai plague focus. The taxonomy of nematodes was determined by the region of the18SrRNA gene; phylogenetic analysis was performed using the Maximum Likelihood method based on the Tamura-Nei model in the Mega 7.0 software. The interaction of theY. pestisKM2083 strain and the nematodes was studied during cultivation on a solid NGM agar medium. Nematodes were observed using microscopes Stemi-2000C (Carl Zeiss, Germany) and Axio Imager Z2 (Carl Zeiss, Germany).Results and discussion. It has been established that the nematodes from the Gorno-Altai high-mountain plague focus used in the work belong to the genusPanagrolaimus. Cultivation of nematodes on the lawn of theY. pestisstrain of the main subspecies of antique biovar, the 4.ANT phylogenetic line for 24 hours did not lead to a reduction in the lifespan of nematodes compared to the control sample, which indicates the absence of toxicity of the used strain towardsPanagrolaimusnematodes. On the cuticle of nematodes, the formation of a biofilm in the genital area and tail has been noted, and accumulations of fluorescent cells of the plague pathogen observed in the digestive tract. The data obtained can indicate the ability of nematodes to carry the plague pathogen in the soil biocoenosis.

Species-level microbiota of ticks and fleas from Marmota himalayana in the Qinghai-Tibet Plateau.

Ticks and fleas, as blood-sucking arthropods, carry and transmit various zoonotic diseases. In the natural plague foci of China, monitoring of Yersinia pestis has been continuously conducted in Marmota himalayana and other host animals, whereas other pathogens carried by vectors are rarely concerned in the Qinghai-Tibet Plateau. In this study, we investigated the microbiota of ticks and fleas sampling from M. himalayana in the Qinghai-Tibet Plateau, China by metataxonomics combined with metagenomic methods. By metataxonomic approach based on full-length 16S rDNA amplicon sequencing and operational phylogenetic unit (OPU) analyses, we described the microbiota community of ticks and fleas at the species level, annotated 1,250 OPUs in ticks, including 556 known species and 492 potentially new species, accounting for 48.50% and 41.71% of the total reads in ticks, respectively. A total of 689 OPUs were detected in fleas, consisting of 277 known species (40.62% of the total reads in fleas) and 294 potentially new species (56.88%). At the dominant species categories, we detected the Anaplasma phagocytophilum (OPU 421) and potentially pathogenic new species of Wolbachia, Ehrlichia, Rickettsia, and Bartonella. Using shotgun sequencing, we obtained 10 metagenomic assembled genomes (MAGs) from vector samples, including a known species (Providencia heimbachae DFT2), and six new species affliated to four known genera, i.e., Wolbachia, Mumia, Bartonella, and Anaplasma. By the phylogenetic analyses based on full-length 16S rRNA genes and core genes, we identified that ticks harbored pathogenic A. phagocytophilum. Moreover, these potentially pathogenic novel species were more closely related to Ehrlichia muris, Ehrlichia muris subsp. eauclairensis, Bartonella rochalimae, and Rickettsia limoniae, respectively. The OPU 422 Ehrlichia sp1 was most related to Ehrlichia muris and Ehrlichia muris subsp. eauclairensis. The OPU 230 Bartonella sp1 and Bartonella spp. (DTF8 and DTF9) was clustered with Bartonella rochalimae. The OPU 427 Rickettsia sp1 was clustered with Rickettsia limoniae. The findings of the study have advanced our understanding of the potential pathogen groups of vectors in marmot (Marmota himalayana) in the Qinghai-Tibet Plateau.

Increased expression of tyrosine protein phosphatase (CD45) on the surface of human blood granulocytes under the influence of the plague microbe vaccine strain &lt;I&gt;Yersinia pestis&lt;/I&gt; EV NIIEG &lt;I&gt;ex vivo&lt;/I&gt; and &lt;I&gt;in vivo&lt;/I&gt;

Tyrosine protein phosphatase (common leukocyte antigen CD45) regulates FcᵧR-mediated cell signaling and secretory function of neutrophilic granulocytes (NG) when interacting with antigen-antibody immune complexes. The aim of the work is to study changes in the expression of CD45 on the surface of human granulocytes in ex vivo modeling of bacteremia by live cells of the plague microbe vaccine strain Yersinia pestis EV NIIEG and to evaluate the priming effect of the live plague vaccine (LPV) in vivo in terms of this parameter. The expression density of CD45 on NG was determined by flow cytometry in conventional units of fluorescence intensity (MFI) after staining the cells with the CD45-FITC labeled mouse antibody reagent (Backman Coulter, USA) during immunophenotyping of blood leukocytes according to the Lyse/No Wash protocol. In donors not previously vaccinated against plague (group 1), the value of the indicator was assessed before and 30 min, 2 h, 6 h after the addition of Y pestis EV cells to whole blood at a dose of 108 mc/ml, as well as 1 month and 6 months after the primary anti-plague vaccination. In individuals who had previously been repeatedly vaccinated with LPV in the territory of the natural plague focus (group 2), CD45 expression on blood granulocytes was determined one year after the last annual vaccination, and then 1 month and 6 months after revaccination. Getting into human blood, living cells of the vaccine strain Y pestis EV of the plague microbe induced a change in the NC phenotype already after 30 minutes, associated with a 3.5-fold increase in the surface expression of CD45, which remained at an elevated level for 6 hours. The studied indicator depended ex vivo on the degree of resistance of plague microbes to phagocytosis and killing of NG. Plague vaccination had a similar stimulating effect on human peripheral blood NG in vivo. Under the influence of HPV, CD45 expression increased on blood NG in groups 1 and 2 one month after vaccination, and the changes persisted in volunteers for 6 months. The experimental data obtained in the work may reflect the result of NG priming with lipopolysaccharide and other Y. pestis antigens. The registered functional activation of NG by expression of tyrosine protein phosphatase probably indicates the formation of “immune memory” at the level of innate immunity cells under the influence of LPV, the functioning of which explains the development of a faster and more intense antigen-specific immune response to repeated introduction of the plague vaccine into the body.

The &lt;i&gt;Yersinia pestis&lt;/i&gt; aggregation as a functional adaptation to the flea organism (review)

The understanding of mechanisms and conditions of plague microbe aggregation in vectors (fleas) organisms has been of interest for a long time, and, with start of biofilm research in 1990s, it got a new perspectives.&#x0D; With the aim to determine the characteristics of the plague microbe aggregation in the organism the main vector in Tuva natural plague focus flea of Citellophilus tesquorum species, the data of many years of experimental studies focused on typical virulent strains of Yersinia pestis subsp. pestis were summarized and analyzed. Ectoparasites were infected and fed on long-tailed ground squirrel (Spermophilus undulatus), which is their natural host and main carrier of plague in Tuva natural plague focus. Interaction between Y. pestis and fleas were estimated using the rate of individuals with conglomerates bacterial lumps, formed during feeding, and blocks in the proventriculus foRmed during feeding and throughout the whole experiment registered in alive fleas after bloodsucking, and also using frequency of causative agent transmission to animals used for feeding.&#x0D; The analysis identified factors influencing the frequency and dynamics of different Y. pestis aggregate types forming into C. tesquorum, and suggest that these processes are functional adaptation of microbe to the flea organism.

Results of a Joint Epizootiological Survey of Transboundary Natural Plague Foci of the Russian Federation and Potentially Focal Territories of the Republic of Kazakhstan in 2019–2022

Consolidation of the efforts in implementation of epidemiological surveillance and control over plague and other dangerous natural-focal infections is an essential aspect in ensuring epidemiological well-being as regards particularly dangerous infectious diseases in the territory of natural plague foci and potentially focal territories located within the borders of the Russian Federation and the Republic of Kazakhstan. The aim of the work was to carry out a joint epizootiological survey of the transboundary territories of the Volga-Ural sandy natural plague focus and the territory of the East Kazakhstan region of the Republic of Kazakhstan (RK) potentially focal for plague over the period of 2019–2022. Materials and methods. Samples of field materials, collected during the epizootiological survey of the territory of Kazakhstan, were studied using bacteriological, molecular-genetic, and immune-serological methods. Results and discussion. We have obtained the current evidence on the spatial-biocenotic structure, the circulation of pathogens of dangerous natural-focal infectious diseases in the transboundary territories of Eastern and Western Kazakhstan. It has been established that the conditions that contribute to the possibility of human infection with plague and other dangerous infectious diseases in case of the aggravation of epizootic situation in the foci or importation of the pathogens into the territory are in place.

Improvement of Epidemiological Surveillance of Natural Plague Foci of the Russian Federation and the Forecast of Their Epizootic Activity for 2023

The aim of the work was to assess the epidemic situation on plague in the world and epizootic activity of natural plague foci of the Russian Federation in 2022. Following the implementation of comprehensive preventive interventions plans, there was a decrease in the epizootic activity of the Gorno-Altai high-mountain and Tuva mountain natural foci, the cessation of plague epizootics in the Central Caucasian high-mountain focus. The total area of epizootics in the Russian Federation in 2022 reached 248.3 km2, which is 7 times less than in 2021. Infected animals were not found in the Tersko-Sunzhensky low-mountain, Dagestan plain-piedmont, Caspian North-Western steppe, Volga-Ural steppe, Trans-Baikal steppe, Volga-Ural sandy, Caspian sandy, East Caucasian high-mountain natural foci. Persistence of tense epizootiological situation in 2023 is predicted for the territory of the Altai Republic and the Republic of Tuva. The prospects of using the GIS portal of the Russian Anti-Plague Institute “Microbe” of the Rospotrebnadzor for an operational assessment of the actual epidemiological situation in natural plague foci are substantiated.

Fleas (Siphonaptera) of mammals and birds of the southern part of the Caspian sandy natural plague focus

The data on the taxocenoses of fleas of rodents, other mammals and birds of the Stavropol part of the Caspian sandy natural plague focus (43) for the period 1990-2015 are presented. As a result of long-term (more than 25 years) observations, it was possible to identify a more complete composition of flea taxocenoses in the plague focus, confined to individual feeders. The conducted studies prove the possibility of the existence of a complex parasitic system with the participation of secondary (additional) and accidental vectors and carriers of the causative agent of the plague, which may have important epizootological significance.