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Background: Hemorrhagic fever with renal syndrome (HFRS) occupies a leading place among natural focal human diseases in the Russian Federation. Sporadic incidence of HFRS-Sochi has been annually recorded in the Krasnodar Territory since 2000. The group outbreak of the HFRS-Sochi was first registered in Gelendzhik in the fall of 2013., Methods: Serological methods were used: indirect immunofluorescence, enzyme immunoassay, FRNT in Vero cells, and methods for the viral RNA detection: PCR and RT-PCR., Results: Data of clinical, epidemiological, immunological and molecular studies of 3 out of 4 cases in HFRS-Sochi outbreak are presented. Severity of the disease correlated with early gastrointestinal disorders appearance. Patient MA gastrointestinal disorders were joined on day 3 of a fever. Clinical and laboratory studies revealed signs of kidneys, liver, pancreas damage, bilateral hydrothorax, bilateral polysegmental pneumonia and polyneuropathy. As a result of long-term treatment, the patient recovered. Patient AA had gastrointestinal disturbances the next day after fever onset. The patient was not saved, despite early hospitalization. Hantavirus antigen and RNA were detected in the lung tissues 2 out of 10 Black-Sea field mice captured in the affected area, as well as in the organs of deceased patient. The most severe clinical course of the disease in close relatives, son and father, with a fatal outcome in the latter case may be the result of genetic features. The severity and outcome of the disease was not depend on day of hospitalization and correlated with the early manifestations of gastrointestinal disorders., Conclusions: Presented data confirm high virulence and pantropism of the Sochi virus, as well as the epidemiological role of Black-Sea field mouse (Apodemus ponticus) as the host of the Sochi virus and the source of human infection., Competing Interests: The authors declare no conflict of interest.

Aim: Typization of natural foci of HFRS of the Republic of Bashkortostan and differentiation of their territories. by the degree of potential epidemic hazard., Materials and Methods: Materials of epizootologic and epidemiologic monitoring of natural foci of HFRS of the Republic of Bashkortostan for 1980 - 2014 were used. Evaluation of area of territory with high, medium and low potential epidemic hazard by HFRS was carried out taking into account multi-year param- eters of morbidity by administrative districts of the Republic of Bashkortostan. 3 gradations of morbidity level by HFRS - more than 201, 101 - 200, less than 100 per 100 thousand of the population - were used for epidemiologic differentiation ofthe territory., Results: 3 main landscape- epidemiologic types of HFRS foci were isolated - forest, forest-barrens, barrens, as well as their landscape variants. The area with a high degree of potential epidemic hazard by HFRS was estab= lished to be around 3.8%; medium - 15.9%, low - 80.3%.of the whole territory of the Republic of Bashkortostan., Conclusion: -A necessity of a differentiated approach to territories with various degree of potential epidemic hazard by HFRS is justified during execution of prophylaxis activi- ties.

Aim: Examine features of natural, natural-anthropourgic and anthropourgic foci of hemorrhagic fever with renal syndrome (HFRS) in various, mostly forest, biotopes of typical barrens due to differences of non-specific HFRS prophylaxis in foci of various types., Materials and Methods: Epizootological and epidemiologic data from 1998 to 2012 were analyzed, gathered in HFRS foci of all types in Saratov area of Saratov Region (typical barrens). 14,606 trap-nights were worked off and 2669 small mammals were procured. The most significant population-ecologic and ecologic-epizootological methods and criteria were used for comparative analysis of differences for 3 types of foci., Results: Based on analysis of multi-year data seasonal differences for HFRS foci of various types were shown by 10 population-ecologic and ecologic-epizootologic criteria., Conclusion: The results obtained allow to state that modern means and methods of non-specific prophylaxis of HFRS and other zoonoses in foci of various types different significantly. This allows the most rational use of material and financial resources.

Aim: Determine qualitative and quantitative criteria of evaluation of features for natural, natural-anthropourgic and anthropourgic foci of hantaviruses (using hemorrhagic fever with renal syndrome--HFRS foci as an example), that have formed in various areas of Saratov Region., Materials and Methods: Epizootological and epidemiologic data from 1998 to 2012 were analyzed. During this period in all the types of foci of Atkarsk area (Northern barrens) 13,004 trap-nights were worked off, 2577 small mammals were procured. Genetic, population-ecological and ecological-epizootological methods and criteria were used for comparative analysis of 3 types of loci: PCR diagnostics and sequencing of pathogenic for humans hantaviruses, species cadaster and features of season dynamics of species composition of hantavirus carriers, domination indexes, parameters of quantity and infection of carriers by hantaviruses; distribution of the latter by biotopes, degree and character of population contacts with natural-foci complexes, epizootic potential of foci., Results: Based on multi-year data analysis features of 3 types of HFRS foci were shown in various, mostly forest, biotopes of Northern and a part of typical barrens. A stable domination of Pumala genotype hantavirus was noted; a weakly expressed circulation in parasite systems with Apodemus genus carriers, first of all Dobrava genotype Apodemus agrarius, was established as well., Conclusion: A certain specter of most universal criteria;that are closely interconnected, are necessary during typing of HFRS foci and a number of other zoonozes.

For the period from 2001 to 2011 zoological and epizootological studies in more than 100 points of Northwestern Caucasus including territories of Krasnodar Region and Republic of Adygea were carried out. 8723 specimens of small mammals represented by 20 rodent species and 7 insectivorous species were captured and examined. Organs and blood from 5057 specimens of creatures were studied for hantavirus infection. The presence of natural foci of circulation of 2 species of hantavirus--Dobrava/Belgrade and Tula--was established. Sochi viruses and presumably Kurkin with main natural hosts--Caucasian wood and field mice belong to the first species. Tula and Adler viruses with the main host--Microtus genus vole belong to the second species. Quantitative characteristics of infection of small mammals of various species during different seasons and years on the examined territories were obtained, that allowed to create a map of allocation of foci of hantavirus circulation that differ by structure.

From 2000 to 2011 85 600 cases of hemorrhagic fever with renal syndrome (HFRS) were registered in Russian Federation. Epidemically active foci of HFRS infection are located generally in temperate latitudes of the European part and the Far East. In the Far East regions whose fraction of all the HFRS disease cases in Russia is around 2%, the causative agents of the infection are Hantaan, Amur, Seoul hantaviruses, the natural reservoir for those are striped field mouse, Korean field mouse and brown rat. In the European part of Russia the causative agent of the infection are Puumala hantavirus as well as 2 genetic subtypes of Dobrava virus, the main reservoirs of those in the nature are bank vole, striped field mouse and Black Sea field mouse, respectively. 9 strain of Puumala and 10 strains of Dobrava virus were isolated. Based on sequencing of Dobrava virus strains significant differences were detected between Dobrava virus strains isolated from Black Sea field mouse from Sochi and striped field mouse from Lipetsk Region. Cultural inactivated vaccine against HFRS was developed and completed preclinical trials.

The findings suggest that there are natural foci of hantavirus infection in the Tambov Region. There is evidence that Dobrava/Belgrade hantavirus (DOB-Aa) was a leading etiological agent in the outbreak of the disease in the winter of 2006-2007. Epidemiological analysis showed that the outbreak of hemorrhagic fever with renal syndrome (HFRS) afflicted the region during November to April, by reaching its peak in January (52.2%). Among the patients with HFRS, rural dwellers were 91%. People were infected with the virus mainly by taking care of domestic animals (97.2%). The reservoir of the virus and the source of its human infection in the outbreak was a field mouse, its western subspecies Apodemus agrarius agrarius, which was absolutely dominated among all the virus carriers.

This paper presents data on the detection of hantavirus in the excretory organs of Apodemus mice which are natural carriers of pathogenic hantaviral serotypes in the Primorye Region. Acute infection periods were detected in naturally infected rodents with the highest hantavirus dissemination to the environment in different phases of rodent population cycles. There was a relationship between the rise of morbidity and the seasonal manifestation of hemorrhagic fever with renal syndrome morbidity and activity of hantavirus reproduction in the murine excretory organs.

Twenty-six patients with hemorrhagic fever with renal syndrome (HFRS) were revealed as a result of serological examination of 582 patients with fever living around Sochi town. Etiologic role of Dobrava virus subtype as the cause of HFRS was assessed by immunofluorescent and ELISA assays, and neutralization test. The principal host of this virus and source of infection for humans is Caucasian forest mouse Apodemus ponticus. HFRS morbidity was sporadic and not dependent from patients' occupation and season. Comparative analysis of clinical and laboratory data from HFRS cases caused by DOB/Sochi and DOB/Lipetsk subspecies, as well as Puumala virus showed higher proportion of severe forms of disease in patients with HFRS from Sochi.

A new formula for the calculation of the endemicity index of the territory affected by hemorrhagic fever with renal syndrome (HFRS) based on empiric data collected in the Volga region near Saratov in 1982-2000 is proposed. As found in this research 21% of the administrative districts of the region have a high endemicity level (with the average index for several years reaching 35 points), 8% of the districts have a medium enemicity level (20 points) and 71% of the districts--a low endemicity level (9 points). It is pointed out that under conditions of financial constraints territories with high and medium endemicity levels should be first examined for HFRS; these territories should also be given priority in prophylactic deratization in the field and human settlements.

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.

The results of the ecological and epidemiological study of hemorrhagic fever with the renal syndrome (HFRS) in the Kirov region for the period of 1987-2000 are presented. HFRS morbidity rate varied from 1.3 to 13.7 per 100,000 population, which corresponded to the figures registered in the Volga Vyatka region. Cases of HRFS were mainly (90%) registered in three southern districts of the region. The moderate degree of correlation between morbidity rate and the number of wild mammals (r = 0.55) was established. Periodic morbidity rise occurred every 3 years. In 1998-2000 the contamination of wild mammals with HFRS virus increased and reached 7.6-9.5%. Infection factors connected with everyday human activities somewhat prevailed, industrial and agricultural types of infection constituting 43.8%. Males aged 20-49 years prevailed among the patients. Morbidity rate among urban dwellers exceeded that among town residents.

A special search program for finding out hidden periodicity was used; such program made it possible to put in order the apparently chaotic sequence of numerical data that are summed up to form the resulting curve, the latter reflecting the actual dynamics of the epidemic process. The cyclic character of morbidity in tick-borne encephalitis, hemorrhagic fever with the renal syndrome (HFRS), tularemia and leptospirosis among the population of Russia for the last 45-54 years was revealed. In tick-borne encephalitis cycles lasting 17-18 years with secondary wave having the period of 3-4 years were found out. In HFRS the main cycle lasts for 16 years and has secondary rises every 3-4 years. In tularemia the main cycles last for 17 years; secondary rises and drops in morbidity were also found to occur every 3-4 years. In leptospirosis regular rises and drops in morbidity were found to occur every 4-5 years.

The brief retrospective analysis of morbidity, epizootological data and preventive measures with respect to haemorrhagic fever with renal syndrome (HFRS) during the whole period of its registration on the territory of the Republic of Bashkortostan along with the structure of HFRS morbidity during epidemic seasons of 1998 and 1999 is presented. The main causes of decreased HFRS morbidity in 1998, its rise in 1999 as well as prognosis for the year 2000 were detected. The level of HFRS morbidity among the population was found to be directly related to the number of rodents and their infection rate. The basic strategy of epidemic control interventions has been proposed.

The kinetics of reaction between hemagglutinating antigens and immune sera to 10 hantavirus strains (7 isolated in the Primorye territory and 3 in other regions) was studied in the cross kinetic hemagglutination inhibition (KHAI) test. An A parameter is suggested for evaluation of the similarity and differences between the studied strains. This parameter helped detect antigenic differences between Hantaan and Seoul viruses and the inter-type differences between Hantaan-like strains. KHAI is more specific than HAI studies of antigenic relationships between strains of different hantavirus serotypes.

Epizootological, serological, and molecular virological analysis of an outbreak of hemorrhagic fever with renal syndrome (HFRS) in the Egoryevsk district of Moscow region (September 1995-January 1996) has been carried out. Hantavirus (Puumala) antigen and virus-specific antibodies were isolated from bank voles captured in the endemic focus. Anti-Puumala antibodies were detected in the sera of all HFRS patients and in 2% healthy residents of the endemic focus. Analysis of nucleotide sequence (RNA from hantavirus-positive lung of a bank vole) showed that the studied hantavirus is a distinct genotype of Puumala virus. Hence, a new highly active natural focus of HFRS associated with Puumala virus, dangerous for the population, has been revealed in Moscow region.

The outbreak of hemorrhagic fever with renal syndrome (HFRS) in the Republic of Bashkortostan, resulting in 10,057 registered cases of the disease (287 cases per 100,000 of the population), was analyzed. HFRS cases among the population were registered in 52 out of 54 regions of Bashkortostan. 31% of the total number of patients were the inhabitants of rural regions (170 cases per 100,000) and 69% were urban dwellers (295 cases per 100,000), mainly in Ufa (512 cases per 100,000). HFRS morbidity among males was fourfold higher than among females. In 70% of cases persons aged 20-49 years were affected. 5% of the total number of patients were children aged up to 14 years. In 34 cases (0.4%) the severe clinical course of the disease had a fatal outcome. Cases of HFRS were registered from April 1997 till March 1998 with the highest morbidity rate observed during the period of August-December. In most cases (46.8%) both urban and rural dwellers contacted infection during a short-term stay in the forest. As the result of the serological examination of the patients, all HFRS cases were etiologically attributed to hantavirus, serotype Puumala. The main natural reservoir of this virus and the source of human infection in Bashkortostan were bank voles (Clethrionomys glareolus), the domination species among small mammals in this region.

The prevalence of Seoul virus in the Primorie territory is presented and its significance in the morbidity structure with regard to hemorrhagic fever with the renal syndrome (HLPS) is discussed. Epidemiological and clinical manifestations of HLPS caused by Seoul virus are described. The authors conclude that in the urban foci of HLPS it is associated mainly with Seoul virus, while in the rural foci, with Hantaan virus.

The data on the relationship between the epizootic process in the population of mice (the source of Hantavirus infection) and the seasonal manifestations of morbidity in hemorrhagic fever with renal syndrome (HFRS) in the southern region of the Russian Far East are presented. The asynchronous course of the epizootic process in the population of rodents causes irregularity in the spread of HFRS in the region and periodicity in the appearance of foci. Seasonal rises in HFRS morbidity coincide with the activity of the epizootic process in the population of mice: spring-summer rises with an increase in the number of infected rodents in the populations of large Japanese field mice and autumn-winter rises in voles.

Results of serologic screening of small mammals for antigen of the virus of hemorrhagic fever with the renal syndrome (HFRS) and of testing human sera for antibodies to this virus in Moldova are reviewed. A total of 9946 animals belonging to 22 species and blood sera of 792 healthy donors were examined in 1983-1990. HFRS virus antigen was detected in 30 animals of 9 species, with the highest incidence of the antigen in gray voles. Two serotypes of Hantavirus were found to circulate in small mammals: Puumala and Hantaan. Screening of healthy humans revealed antibodies to HFRS virus in 7.8%. Natural foci of HFRS were detected in 23 of the 44 administrative territories of the Republic situated in 5 landscape geographical provinces.

In blood samples taken from 33 patients having hemorrhagic fever with the renal syndrome (HFRS) the capacity of neutrophil granulocytes for the ingestion of bacteria and for the reduction of tetrazolium nitro blue, as well as the content of cation protein in the cytoplasm of neutrophils and the concentration of lysozyme in the blood serum of patients, were studied. The study revealed an increase in the values of the above characteristics in comparison with similar data obtained in healthy subjects. Changes in the characteristics of the functional activity of neutrophils were found to depend on the period of the clinical course of HFRS.

According to the data contained in the materials provided by the hospital of infectious diseases of the Khabarovsk Medical Institute, in the recent decade hemorrhagic fever with the renal syndrome, together with pseudotuberculosis, played the leading role in the structure of morbidity caused by natural foci of infections. The distribution of patients in social groups and different important factors of the epidemiology of this disease are considered. Taking into account a high morbidity level in this disease and its social grounds, the necessity of further improvement of the system of nonspecific prophylaxis is substantiated.

Lungs of 3159 animals of the forest complex from 90 areas of 30 administrative districts of Tyumen Province were examined by enzyme immunoassays for antigen of hemorrhagic fever with renal syndrome (HFRS) during 5 years, 1985-1989. The antigen of HERS virus was detected in the lungs of mammals of 8 species: Clethrionomys glareolus and Cl. rutilus, Siberian and Arctic lemmings (first findings in the world), M. oeconomus, field mouse, common and pygmy shrews. Nearly all the findings refer to the subzone of southern taiga and adjacent areas of subtaiga subzone where Cl. glareolus is the main reservoir of infection and Cl. rutilus an additional one. In the tundra zone, Siberian lemming is the main reservoir of infection and Arctic lemming an additional one. No natural foci of HFRS were found in forest steppe and forest tundra zones. In the subzone of the northern and middle taiga, the antigen was found only on 4 occasions: 3 in common shrews and one in Cl. glareolus (near the town of Khanty-Mansisk). An irregular annual infection rate with HFRS virus was observed in Cl. glareolus as well as its decline from spring to autumn. It cannot be ruled out that lemmings are carriers of a distinct HFRS virus serotype.

For the first time the natural immune stratum to hemorrhagic fever with the renal syndrome (HFRS) among the population of all regions of Bashkiria, a large territory with the highest morbidity level in this infection in the USSR, was studied. 9,176 persons over 15 years of age were examined by radioimmune techniques. Analysis of the immune structure of the population revealed that the share of immune males was higher than that of immune females, but the difference was less than the difference between males and females among the registered HFRS patients. Among children immune persons were almost completely absent. The immune stratum increased rather slowly among persons under 40 years, and only from this age the considerable increase of the immune stratum was observed (up to 16.2%). High risk groups included persons of such professions as forestry workers, truck and tractor drivers, oil workers and prospectors, livestock breeders, builders. These data may be used for the formation of groups to be vaccinated against HFRS in foci with different degrees of activity. Before vaccination the correction of groups to be vaccinated in a given region should be carried out, taking into account the immune structure of the population and the specific features of the local landscape and economy.

The employment of two serological tests (indirect fluorescence antibody technique and neutralization test) demonstrated the leading role of Hantaan virus serotype 1 strains isolated from field mice in the pattern of the incidence of hemorrhagic fever with renal syndrome (HFRS). Proofs of the etiological importance of strains of serotypes 3 and 5 occurring in brown rats and Cl. rufocanus were obtained. No data on any association of human HFRS cases with strains of serotype 4 isolated from reed voles could be demonstrated.

To carry out serodiagnosis and to determine the serotype of the virus causing hemorrhagic fever with the renal syndrome (HFRS), paired sera obtained from 28 HFRS patients, 42 persons with a history of HFRS (1-17 years after convalescence), and 268 serum samples from healthy persons residing at the areas with the natural foci of this infection have been studied by indirect immunofluorescence techniques at the territory of the Amur Province. This study has demonstrated for the first time that, alongside the diseases caused by HFRS virus of serotype Apodemus, HFRS viruses of serotype Rattus and an unidentified serotype serve as the source of infection for the population of the Amur region. The leading role of serotype Rattus in HFRS has been confirmed by the detection of antibodies mainly to this serotype in serum samples taken from convalescents after HFRS and from the healthy population of the areas with the foci of HFRS virus infection.

Clinical, epizootological, and laboratory data for 9 endemic foci of hemorrhagic fever with renal syndrome (HFRS) were compared. The analysis covered 5120 cases of HFRS. It was established that in the foci, where the leading role is played by field mouse and Japanese field mouse, HFRS is caused by the 1st serotype of HFRS virus, and the clinical course of the disease is quite severe. In the natural foci with the predominance of redbacked vole, the 2nd serotype of the virus circulates and the disease is of moderate severity or mild. In each individual case, however, both serotypes of the virus may produce both mild and severe diseases.

The results of the studies on wild rodents trapped in the areas of the Leningrad region visits to which were associated with human cases of hemorrhagic fever with renal syndrome (HFRS) are presented. In one of these areas 30% of bank voles were found to be infected. Specific fluorescence of high intensity was found in ctyostat sections of lungs from bank voles treated by the indirect fluorescent antibody procedure. Fluorescent granules, their clumps and large conglomerates were localized in the cytoplasm of alveolar epithelium cells. The antigen-containing cells formed foci within which 70% or more elements showed fluorescence or were found diffusely throughout the section (dozens of infected cells in each field of vision). The antigen-containing lung sections were used for the indirect immunofluorescence test with sera from the subjects clinically diagnosed as having HFRS. Positive results in titers ranging from 1 : 10 to 1 : 1280 were obtained in 6 out of 7 subjects examined. Examinations of paired sera from one of them revealed an over 100-fold rise in titers during the 3rd-7th week after the onset of the disease.

The use of the serological method (the indirect fluorescent antibody test) for the examination of 255 persons coming in contact with patients having hemorrhagic fever with the renal syndrome (HFRS) in the foci of this infection where outbreaks of group infection had been registered made it possible to detect mild, unclear and asymptomatic forms of HFRS in 17.7-20.9% of cases. The simultaneous titration of 317 serum samples with two antigens revealed that HFRS virus of serotype 1, similar to strain Hantaan from Korea, may cause, besides the classical forms of the disease, the development of mild and asymptomatic forms of this infection.

The study of 9,176 serum samples obtained from all regions and 15 cities of Bashkiria, carried out by the method of radioimmunoassay with the use of the antigen of hemorrhagic fever with the renal syndrome (HFRS), has revealed considerable differences in the size of the natural immune stratum of the population (43.9-0.8%). The size of such immune stratum characterizes the activity of natural foci: the largest immune stratum (25.4%) exists among the population of regions with broad-leaved forests, this stratum is somewhat less (12.2-13.2%) in regions with combined coniferous and broad-leaved forest, in regions with different combinations of broad-leaved forests and steppes, as well as mountain forests. On the Aĭsko-Kungurskaia forest-steppe territory and in regions characterized by a combination of steppe areas with mountain forests the immune stratum has been found to be even lesser (7.3-8.4%). The least immune stratum (3.4%) exists in steppe regions. By comparing the percentage of the population immune to HFRS and having had the diagnosis of HFRS over the period of 30 years the quality of the clinical diagnosis of this infection on the given territory may be determined.

In natural foci of hemorrhagic fever with renal syndrome (HFRS) located in agricultural landscapes, rodents of various species are infected with the virus, however, regular HFRS epizootics are observed in field mice which present the highest abundance of infected animals in the population. Annually, a high direct correlation is observed between the population density of rodents and the percentage of animals with HFRS virus antigen in the blood and lungs. In 1981, there was a high correlation between the occurrence of rodents with Gamasid mites and the presence of the antigen in the blood. All the foregoing suggests that HFRS agent exists in natural foci due to a combination of different transmission mechanisms (obligate-transmissive mechanism) and penetrates into murine rodents by various modes: air--dust-borne and/or alimentary and transmissive. Non-transmissive modes are likely to be the leading ones.

Radioimmunoassay was used for examinations of 21,488 serum specimens from the population of 145 areas of 8 regions and 2 republics. The immune portion comprised 8.8% to the west of the assumed border and 2.7% to the east (t = 20.7). Active natural foci of the infection were found in individual territories located to the east of the assumed border (areas of Saratov Province to the north of the Irgiz River, trans-Ural areas of Bashkiria, southern taiga areas of Sverdlovsk, Tyumen, and northwestern Omsk Provinces). The extreme eastern points of the endemic area are Tevriz, Tary, and Znamenskoe Districts of Omsk Province. The areas of Siberian forest steppe, the steppe areas of western Siberia and those on the left bank of the Volga (Zavolzhye) are free from the infection foci. Natural foci of infection were found in the taiga part of the Komi ASSR, whereas they were absent in the forest tundra zone.

The sporadic character of the occurrence of hemorrhagic fever with the renal syndrome in the Primorye Territory has been established. Three rodent species have been found to be spontaneously infected with the causative agent of this disease. Antibodies in patients with this disease are detected at its early stages and persist for a long time after convalescence. The possibility of the formation of a contingent immune to hemorrhagic fever, due to the persons who have had mild and asymptomatic forms of this infection has been shown.

The epidemic manifestation of the most active natural foci of HFRS in the USSR on the territory of Bashkiria is described. The authors compare two epidemic seasons of 1975-1976 and 1977-1978. Besides the number of rodents, the rise of morbidity is influenced by their early multiplication and weather conditions. The early appearance of the stable snow cover facilitates a rapid drop in the number of NFRS cases as early as in October, while prolonged autumn with rains, snow, periods of thaw and ice-covered ground leads to a rise in NFRS morbidity occurring in autumn and winter and ending only in March. Weather conditions also influence the epidemiological structure of morbidity.

For the detection of specific antigens of hemorrhagic fever with renal syndrome (HFRS) virus, examinations were carried out covering 8.061 animals of 23 species trapped in the Murmansk, Archangelsk, Vologda, Novgorod, Pskov, Leningrad regions, the Komi ASSR, Estonian SSR, Latvian SSR, and Lithuanian SSR in 1984-1987. Different activity and variable species-specific composition of animal virus carriers in the north, south, and west of the north-western region were demonstrated. Circulation of HFRS virus of the first, "eastern", serotype has first been detected in the European USSR.

Examination by the enzyme-immunoassay of organs of 10 small mammal species trapped in different landscape zones of the Estonian SSR revealed the presence of HFRS virus antigen in organs of bank voles and field mice. Radioimmunoassay studies of serum specimens from donors demonstrated the presence of antibody to HFRS virus in 2.54% of those examined.

The evidence of the existence of natural foci of HFRS in Penza region has first been presented on the basis of serological examinations of patients and normal population as well as HFRS virus antigen demonstration in the lung tissue of small mammals. An outbreak of HFRS among children in a pioneer camp is described. Aerogenic infection of the children contracted from HFRS virus-infected bank voles (Clethrionomys glareolus) living near the camp is assumed. The detection of HFRS antigen in 5 species of small mammals indicates the polyhostal nature of HFRS foci existing in the region.

The circulation of the causative agent of hemorrhagic fever with renal syndrome (HFRS) in Georgia was studied. Altogether, 7,938 small mammals of 16 species trapped in 23 administrative areas of the republic were examined, and the specific antigen of HFRS virus was detected in 308 (3.8%). In serological examinations of 10 patients, antibody to HFRS virus was found in 4. Analysis of the above results indicates the existence of natural foci of HFRS in the Georgian SSR.