[Detection of natural foci of hemorrhagic fever with renal syndrome on the territory of the Komi ASSR]. / Obnaruzhenie prirodnykh ochagov gemorragicheskoi likhoradki s pochechnym sindromom na territorii Komi ASSR.

Natural foci of hemorrhagic fever with the renal syndrome (HFRS) have been found for the first time in the Komi ASSR. The main source of the causative agent in this territory was Clethrionomys glareolus the average infection rate of which was 4.4% and in some areas as high as 22.6%. For the first time in the republic the portion of human population naturally immune to HFRS was determined, comprising 5.2% of the population. The immune structure of the population did not differ from that in other focal territories of the European part of the USSR.

[The disposition of natural foci of hemorrhagic fever with renal syndrome in different landscape areas of Tyumen Province]. / Razmeshchenie prirodnykh ochagov gemorragicheskoi likhoradki s pochechnym sindromom v razlichnykh landshaftnykh zonakh Tiumenskoi oblasti.

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.

[Serologic examination of patients with hemorrhagic fever with renal syndrome in the European part of the USSR]. / Serologicheskoe obsledovanie bol'nykh gemorragicheskoi likhoradkoi s pochechnym sindromom v evropeiskoi chasti SSSR.

Certain features of humoral immunity in patients suffering from hemorrhagic fever with renal syndrome (HFRS) in the territory of the European USSR were established: a trend for increasing antibody levels for a long time after convalescence (approximately 6 months) and the lack of significant decline of antibody levels for many years (5-10). Comparative clinico-serological studies revealed the occurrence of subclinical and atypical forms of HFRS disease.

[Stratum of the population of the Bashkir ASSR with natural immunity to hemorrhagic fever with renal syndrome]. / Estestvennaia immunnaia prosloika naseleniia Bashkirskoi ASSR k gemorragicheskoi likhoradke s pochechnym sindromom.

Natural immunity to hemorrhagic fever with the renal syndrome (HFRS) in the human population of the Bashkir ASSR having the highest incidence of this infection was first studied using radioimmunoassay. The antigen was a suspension of lungs of rodents from natural foci containing high antigen titres. When 1726 human sera from 8 districts and 2 towns were examined, antibodies to HFRS were found in 20.1%, with variations from 6.9% to 41.5% in different territories. No relationship between the percentage of immune subjects and average incidence values for 17 years was found. In the immune population, men accounted for 21.3%, women for 19.3%. Among subjects under 40, the immune stratum was lower (17.5%) than among older subjects (26.2%). The percentage of immunity was found to depend on the occupation of the population. No significant difference in immunity could be found in persons with different blood groups. Antibody in HFRS convalescent was shown to persist in high titres for up to 20 years after the onset of the disease.

[Exact determination of the eastern border of the European portion of the nosogeographic range of the hemorrhagic fever with renal syndrome]. / Ob utochnenii vostochnoi granitsy evropeiskoi chasti nozoareala gemorragicheskoi likhoradki s pochechnym sindromom.

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.

[Circulation of the virus of hemorrhagic fever with renal syndrome among small mammals in the territory of the USSR]. / Izuchenie tsirkuliatsii virusa gemorragicheskoi likhoradki s pochechnym sindromom sredi melkikh mlekopitaiushchikh na territorii SSSR.

Over 55,000 small mammals of 72 species trapped in 62 administrative territories practically in all landscape-geographical zones of the USSR were examined in 1980-1985. The use of current laboratory methods demonstrated a wide spread of HFRS virus in the territory of this country, involvement in the epizootic process of most species of forest and steppe murine rodents and insectivora. In each landscape zone, the main carriers of the HFRS agent were established, represented, as a rule, by the basic species having a high and stable population density.

[Time periods of antibody preservation in patients convalescing from hemorrhagic fever with renal syndrome in European foci of the infection]. / O srokakh sokhraneniia antitel u rekonvalestsentov gemorragicheskoi likhoradki s pochechnym sindromom v evropeiskikh ochagakh infektsii.

The radioimmunoassay of serum samples from 76 convalescents after hemorrhagic fever with the renal syndrome (HFRS), that took place in 1964 in Ufa, revealed the presence of specific antibodies in 75% of the convalescents. The absence of antibodies may be attributed both to their loss in some of the convalescents and to mistakes in the clinical diagnosis. The study of serum samples from 19 convalescents who had the infection in 1960 during the laboratory outbreak of HFRS at the Gamaleya Institute of Epidemiology and Microbiology (Moscow) showed the presence of antibodies in all convalescents. In both groups the infection was linked with common red-backed voles (the Western serological variant of the virus).

[The immune structure of the population of the Bashkir ASSR in connection with hemorrhagic fever with renal syndrome and the relation of indices of collective immunity to morbidity and the nature of the landscape]. / Immunnaia struktura naseleniia Bashkirskoi ASSR v otnoshenii gemorragicheskoi likhoradki s pochechnym sindromom i sviaz' pokazatelei kollektivnogo immuniteta s zabolevaemost'iu i kharakterom landshafta.

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 Aisko-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.

[The intensity of the immune response to the hemorrhagic fever with renal syndrome virus among different population groups of Bashkortostan]. / Velichina immunnogo otveta na virus gemorragicheskoi likhoradki s pochechnym sindromom sredi razlichnykh grupp naseleniia Bashkortostana.

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 topographic zoning of natural HFRS foci in Russia]. / Landshaftnoe raionirovanie prirodnykh ochagov GLPS v Rossii.

Using large selections the unified system of landscape districting of HFRS natural foci with allocation of special geo-botanical provinces has been developed. This permits to avoid various deviations were found to appear during association of epizootiological and epidemiological indexes of separate towns and rural districts when estimating regional parameters. Adequacy of the offered system in confirmed by five-fold increase of the correlation between HFRS epizootiological parameters and antibody prevalence rate in humans. The steady maximum of all parameters was registered in the province situated in broad-leafed oak-line forests. Minimal values are found to correspond to one located in forest-steppe (with birch and asp forests) which poor fodder potential for rodents is well known. Other provinces between these ones are characterized by consecutive decrease of all index values according to the landscape type. According to estimated natural activity rate all the provinces are divided to three groups. The first one (antibody prevalence rate is above 5%) unites the high activity HFRS natural foci. Their common geographical location is on the territories with highest rodent population rates. The second group (antibody prevalence rate--2-4%) includes HFRS foci with average activity, and the third one (antibody prevalence rate is below 2%)--with low activity. The most of the last group provinces are situated on periphery or behind the bank vole living area.

[Hantavirus infection in bank voles in the natural reservoir. Part 1. Characteristics of an infection process in bank voles]. / Khantavirusnaia infektsiia u ryzhikh polevok v prirodnom ochage. Soobshchenie 1. Osobennosti infektsionnogo protsessa v organizme polevok.

The specific features of hantavirus infection in naturally infected bank voles (Clethrionomys glareolus), the principal host of hantavirus of the serotype Puumala, were studied during long-term observation of individually marked animals in the active focus of hemorrhagic fever with renal syndrome (HFRS) in the south of Udmurtia. The infection time in the bank voles was defined by paired serum seroconversion tests. In the natural focus, hantavirus was shown to cause asymptomatic persistent infection in the bank voles with the body's peak accumulation of the virus and its environmental discharge within the first month of infection. In this period the animals present the greatest epidemic and epizootic hazards. Hantavirus infection has no negative impact on the viability of bank voles.