Natural foci of leptospirosis on the territory of the north-eastern part of the east mountain range of Azerbaijan and their characteristic

Numerous natural foci of leptospirosis infection in which Ap. sylvaticus and M. musculus play the role of the main source, were found on the territory of the north-eastern part of Azerbaijan's east mountain range. The leading place in the aetiological structure of leptospirosis of small mammals is occupied by leptospirae of the serological group Hebdomadis. As a rule, the animals -- Leptospira-carriers -- populate damp biotopes where stable natural foci of disease are formed. Two types of natural foci were established on the given territory, i. e., the marshy-bush type and the mountain-stream type. The foci are characterized by several hosts and several serotypes of Leptospira.     

Natural foci of diseases: the development of the concept at the close of the century

E. N. Pavlovski?'s concept of natural focality of diseases and the development of general knowledge about natural foci and their structural (components), functional (mechanisms of pathogen maintenance), and ecosystem-related organization (assortment and interrelations of ecosystems) are reviewed from principal (in authors' opinion) aspects. The 60-year history of this theory includes three stages at which its scope and contents differed. At the first stage, it concerned transmissible zoonoses. It had been assumed that structurally, natural foci necessarily include the pathogen-vector-host triad, and the functioning of the focus is provided for by only pathogen circulation in terrestrial ecosystems. At the second stage, it became clear that vector is not a necessary structural component of any focus (an example of nontransmissible diseases), although the functioning of foci remained to be unequivocally attributed to the continuous pathogen circulation among animals of terrestrial ecosystems. The third stage is characterized by an understanding that, in general, the presence of a warm-blooded host in the focus is also unnecessary for pathogen survival, and natural foci can be represented by soil and aquatic ecosystems. The only necessary and specific component of any natural focus is the pathogen population. In this context, modern views on natural focality of diseases are reviewed, and the essence of the terms "natural focus" and "epizootic process" is defined. It is proposed to distinguish the phases of pathogen reservation and epizootic spread (circulation) in ecosystems of any type. The current state of this concept provides evidence that, in general biological terms, studies on natural focality of diseases belong to one of the fields of symbiotology.     

Gene typing of infectious tularemia strains isolated from the Stavropol and Krasnodar Territories

The typing of F. tularensis strains by four variable number of tandem repeats (VNTR) loci has been carried out. Among the strains isolated in the Stavropol and Krasnodar Territories seven genotypes have been detected and their spread in different natural foci has been analyzed. The data thus obtained suggest that the VNTR analysis may become an important instrument for studying the structure of the natural foci of tularemia and evolutionary relationships between individual areas of these foci.     

Natural focal infections in the north of the Far East. I. The detection of natural foci of infections in Chukot]

Results of a 3-year complex (zoo-parasitological, viral, bacteriological, and serological) studies of mammals and birds in Chukotka demonstrated the presence of natural foci of pseudo-tuberculosis, intestinal yersinosis, salmonellosis (heidelberg), and of tick-borne encephalitis. The existence of natural foci of tularemia and endemic rickettsioses is supposed on the basis of serological data.     

Infectious diseases in natural reservoirs: epidemic situation and morbidity in the Russian Federation and prophylactic measures

The analysis of morbidity in infections with natural foci in Russia for the period of 1999-2000 indicates that a rise in the number of cases of hemorrhagic fever with the renal syndrome, tick-borne encephalitis, Crimean hemorrhagic fever and West Nile fever with a high proportion of urban population among the patients is registered annually. An increase in the epizootic activity of the natural foci of plague is noted in the absence of morbidity among humans. The appearance of the outbreaks of tularemia is linked nor only with the increased activity of the natural foci, but also with the reduced coverage of the population with prophylactic immunization in endemic regions. This analysis infers that morbidity prognosis in infections with natural foci for 2001 remains unfavorable. The growth of morbidity in these infections is mainly due to the reduction of measures for controlling their vectors both is open nature and in settlements, as well as to low coverage with prophylactic immunization. Urgent complex measures which may ensure effective antiepidemic and prophylactic work for controlling infections with natural foci are presented.     

Combined manifestations of natural foci in the territory of the Vologda province

Based on epizootological and epidemiological investigations in the Vologda province since 1958 till 2000, the combined territorial and temporal manifestations of natural foci of diseases was revealed. A natural focus occupies a complex of biotopes, and in different time the focus is activated in different areas, such as a river plain, marsh, meadow-field, and forest. Most commonly an activation of the natural focus appears in a border zone of three biotopes, namely, a forest, meadow-field, and river plain. A dependence of activation of various natural foci upon local climate conditions and fluctuations of micromammalian host number are considered.     

Epidemiological surveillance on natural-borne infections in the Ulyanovsk region

The analysis of natural foci of haemorrhagic fever with renal syndrome (HFRS) and tick-borne borreliosis on the territory of the Ulyanovsk region is presented. Reduced rat control interventions result in a wide spread of these and other infections with natural focality. Monitoring of natural foci of HFRS, tick-borne borreliosis and arbovirus infections, their typing and determination of main reservoirs are the most promising among epidemiological surveillance methods.     

Influence of the mechanism of transmission of the infective agent on the aetiological structure of leptospiral foci

It has been demonstrated that the differences observed in the aetiological structure of the individual foci of leptospirosis can be explained not only by the affinity of leptospiral serogroups to certain animal species, but also by different mechanisms of transmission of the causative agent of leptospiral infection which can be transferred both by sexual and alimentary routes (in water). It has been demonstrated that mostly one serotype of leptospires predominates in natural foci of leptospirosis, but several in anthropurgic ones. In the author's opinion, leptospiral infection in natural foci is mainly spread by the sexual route through the background species of animals--carriers of leptospirosis, and by the alimentary route in the anthropurgic foci. It is presumed that leptospires of the serogroups Javanica, Australis, Icterohaemorrhagiae, transmitted by the shrew-mice, hedgehogs and rats by the sexual route, are by their origin "ancient" serogroups of leptospires while the serogroups of leptospires isolated from domestic animals, showing predominantly the alimentary route of transmission of infection in the focus, are representatives of the "younger" forms of the evolutional development of leptospires.     

Results of prolonged study of flood plain-swamp endemic foci of tularemia, and its prophylaxis in the Leningrad Region

The results of a prolonged (more than 18 years), comprehensive study have revealed that stable natural foci of tularemia in backwater swamps are widely spread in the Leningrad region. These foci are located in the narrow swampy flood-plains of small watercourses with adjacent meadow areas among forests. Water from such small watercourses can often serve as the indicator of the epizootic process: during the above-mentioned period 346 Francicella tularensis strain have been isolated from water and 86 strains from small mammals. The water factor plays an important role in the circulation of the infective agent in natural foci.     

Characterization of the natural foci of Congo-Crimean hemorrhagic fever on the territory of Ukraine

The natural foci of the Congo-Crimean hemorrhagic fever (CCHF) in Ukraine were characterized by their geographical factors. The circulation of CCHF virus was found to occur mainly in forest and forest-steppe zones irrespective of the location of administrative regions. The territories found to be most favorable for the prolonged existence of the focus of CCHF were those having high humidity. The possibility of using geoinformation technologies for the correction of the boundaries of natural foci, the evaluation of the influence of geographical factors on the circulation of the virus was shown.     

Natural foci of the Moroccan locust (<Emphasis Type="Italic">Dociostaurus maroccanus</Emphasis>, Orthoptera,Acrididae) in Turkmenistan and their current state

The current state of natural foci and the population dynamics of the Moroccan locust Dociostaurus maroccanus in Turkmenistan are described. The slope aspect, micro-relief, plant cover condition, and the degree of anthropogenic impact were considered in natural landscapes. The locations of the natural foci were described using a Garmin eTrex GPS device. The causes and features of changes in the altitudinal and latitudinal distribution of the species’ natural foci in the Kopet Dagh and Koyten Dagh mountains during the second half of the XX and early XXI centuries are revealed. Both lower and upper range limit extensions of the locust foci are shown to have been due to xerophytization of the mountain ecosystems because of excessive pasture use and climate aridization. As a result, Turkmenistan presently supports 15 areas of D. maroccanus outbreaks instead of 12 areas known previously.     

Erysipeloid on the islands of the Ohhotsk Sea. 2. Landscape types of the natural foci of erysipeloid

Cases of skin (skin-artericular) form of erysipeloid were recorded in the islands of the Sea of Okhotsk. The natural foci of the causative agent of this infection were polyhostal and polyvectoral in character. The causative agent of erysipeloid exists among the animals habitating on land and sea. Mass species of animals characteristic of the island landscape served as the sources of infection. Their four landscape types (mountaineous-taiga, of sea coast and rocks, anthropurgic settlement, and of water bodies--salt and freshwater) were preliminarily distinguished by the combination of biocenological, epidemiological, and epizootological peculiarities of natural erysipeloid foci.     

Regional epidemiologic characteristics of combined foci of tick-borne encephalitis, endemic rickettsioses and leptospirosis in Western Siberia

The authors carried out complex study of combined foci of infections with natural foci in Western Siberia and their reflection in human pathology. The results of serological examination of 5917 persons and of 1743 of farm animals in respect to tick-borne encephalitis, Asian tick-borne rickettsiosis, Q-rickettsiosis, and leptospiroses are analysed. Affection of the population with all the four infections in all the landscape zones under study was shown; the intensity of this affection with different infections differed. Combined natural foci of the mentioned infections were found to be widespread; epidemiological significance of such combination was unequal in different ladscapes, this depending on the ladscape characteristics of the natural foci of infections under study and of different ways of transmission of their causative agents.     

Natural foci of leptospirosis on the territory of Moscow in 1995 - 2004

The results of ten-year observations of the natural foci of leptospirosis on the territory of Moscow are presented. Information on the foci, the main species of small mammals (the reservours of the infection), the etiological structure of leptospires, circulating among rodents and insectivores, is given.     

Culture properties of the causative agent of tularemia isolated in natural foci in Stavropol Territory, the Kalmyk ASSR and the Armenian SSR

The strains isolated in natural foci of the Stavropol Territory and the Armenian SSR have been found to belong to the holarctic race of Francisella tularensis, biovar II. In natural foci of the Kalmyk ASSR the strains belonging to biovars I and II have been isolated. The study of the tularecinogenicity of the cultures has revealed the existence of strains which are not sensitive to their own tularecins. The phenomenon of tularecinogenicity in F. novocida has been established. Avirulent strain 319/38 belonging to the non-arctic race is recommended as an indicator strain for the determination of tularecinogenicity.     

Topical problems of rabies: natural foci, the methods of study and control in Central Russia

This analytical review is dealing with the origin and evolution of modern rabies as well as hypotheses concerning the natural foci of rabies infection, the formation of the Central European nosological area of rabies and its eastward shift due to the systematic oral vaccination of the main hosts. The epizootological problems connected with the character of the natural foci of rabies, as well as the methods and prospects of the vaccination of foxes on the territory of Central Russia, are discussed.     

The immune status of the population of the Crimea to the tick-borne encephalitis virus]

The immune status of the Crimean population with respect to tick-borne encephalitis (TBE) virus has been studied. The results of the study confirm the existence of natural foci of TBE in the Crimea. The most active and potentially dangerous foci are located in forests of the mountain area of the peninsula. The study has revealed that humans are mainly exposed to the risk of contacting TBE virus infection during their work and rest in the forest.     

Complex method for epizootiological and epidemiological surveillance

A complex method for the epizootological and epidemiological surveillance of a number of bacterial and viral infections on the territories inside and outside their natural foci has been developed. The investigation techniques are described and the data on the isolation rate of each causative agent in different geographical zones are presented. In the natural foci of plague and tularemia, as well as on the territories outside such foci, the causative agents of intestinal yersiniosis, pseudotuberculosis, salmonellosis, erysipeloid, staphylococci and streptococci, arena- and arboviruses have been isolated from the rodents and ectoparasites under study. The results of this investigation suggest that the method may be recommended for use in medical institutions dealing with the problems of infections originating from natural foci.     

云南省剑川县鼠疫自然疫源地宿主媒介情况分析

了解鼠疫自然疫源地的宿主、媒介群落结构及其种群动态,为提出针对性的鼠疫防控策略与机制提供依据.云南省剑川县属于齐氏姬鼠和大绒鼠鼠疫自然疫源地的核心区,该区域小型兽类种类丰富,存在2种类型鼠疫菌,为进一步研究疫源地的演变提供了重要的现场模型.本文对剑川县1976-2019年鼠疫监测资料进行整理和分析,发现该疫源地室内共捕...     

Ecological Aspects of Evolution of the Plague Microbe Yersinia pestis and the Genesis of Natural Foci

A new hypothesis of the origin of the plague microbe in the Mongolian bobak (Marmota sibirica Radde, 1862) populations in Central Asia during the Pleistocene is based on the ideas of its relative phylogenetic recency. The Late Pleistocene cooling, which induced a deep freezing of the grounds in southern Siberia, Mongolia, and Manchuria, is considered as an inducer of speciation. The main ecological factors of the plague microbe evolution include the species specific behavior of the Mongolian bobak as it prepared to hibernate related to its occurrence in arid petrophytic landscapes and the larval parasitism of the flea Oropsylla silantiewi Wagn., 1898 in winter. Genesis of the plague foci is divided into two periods: natural-historical and biosocial. During the first period, the primary natural foci in Eurasia were formed and, during the second period, synanthropic (rat) and secondary natural foci appeared with the participation of humans in Africa, The New World, and on some tropical islands.