WEST NILE FEVER IN THE SARATOV REGION IN 2013-2015.

West Nile virus (WNV) circulation in the territory of Saratov region and its role in the infectious pathology were investigated. For this purpose, in studies conducted in 2013-2015, suspensions of bloodsucking arthropods, organs of birds and small mammals were analyzed for the presence of WNV markers (antigens and/or RNA). The seroprevalence level in live-stock animals and population of the region was evaluated; clinical samples from patients with symptoms compatible with West Nile fever (WNF) were analyzed. As a result of the investigations, WNV markers were detected in field samples gathered in natural biotopes and in the city of Saratov. Immunity to WNV was detected in horses. A stable domain of persons with immunity to this agent was revealed among regional population. Patients with WNF have been annually registered in the region since 2012. The obtained results confirm active circulation of WNF in the Saratov region, as well as formation of stable natural and anthropourgic foci.

[Gamasid mites of small mammals in the semi-desert territories of the Saratov Trans-Volga region].

The paper contains the data on the species composition and comparative analysis of gamaside mites, parasitizing on small mammals in the semi-desert territories of Saratov trans-Volga region. On the basis of the results of investigations conducted in the Aleksandrovo-Gaisky District in 2008-2013, 18 species of gamaside mites (9 genusus, 5 families) have been recorded. Nine species of maaside mites, which were not found in semi-desert zone earlier were revealed, includiding Hypoaspis (Stratiolaelaps) miles Berlese, 1882, H. (Geolaelaps) heselhausi Oudemans, 1912, H. (G.) lubrica Oudemans et Voigts, 1604, G. et. R. Canestrini, 1881, Haemogamasus citelli Bregetova et Nelzina, 1952, Hirstionyssus eusoricis Bregetova, 1956, Hi. ellobii Bregetova, 1653; five of these species are new for the territory of Saratov Province. As a result of the study of semi-desert zone of Saratov trans-Volga region and taking into account literary data, parasitic fauna of small mammals of Aleksandrovo-Gaisky District was expanded up to 21 species, and of Saratov Province, up to 44 species of gamasid mites.

[IMPACT OF CASPIAN SEA LEVEL FLUCTUATIONS ON THE EPIZOOTIC ACTIVITY OF THE CASPIAN SANDY NATURAL PLAGUE FOCUS].

There is evidence that in 1923-2014 the sharp aggravations of the epizootic situation of plague in the area of its Caspian sandy natural focus after long interepizootic periods are in time with the ups of the Caspian Sea in the extrema of 11-year solar cycles. There were cases of multiple manifestations of plague in the same areas in the epizootic cycles of 1946-1954, 1979-1996, 2001, and 2013-2014. The paper considers the possible role of amebae of the genus Acanthamoeba and nematodes, the representatives of the orders Rhabditida and Tylenchida in the microfocal pattern of plague manifestations.

[CRITERIA OF DIFFERENCE EVALUATION FOR VARIOUS TYPES OF HEMORRHAGIC FEVER WITH RENAL SYNDROME FOCI. HFRS FOCI IN VARIOUS BIOTOPES OF TYPICAL BARRENS].

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.

[Criteria of difference evaluation for-various types of hemorrhagic fever with renal syndrome foci. HFRS foci in various biotopes of northern barrens].

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.

[Formation of focus of West Nile fever on the territory of Saratov Region].

AIM: Detection of circulation of West Nile virus (WNV) on the territory of Saratov Region and prerequisites for formation of natural focus of West Nile fever (WNF), determination of the role of WNV in infectious pathology on the territory of the region. MATERIALS AND METHODS: of organs of small mammals, birds, blood-sucking arthropods for the presence of WNV markers (antigens and/or RNA) were studied. Clinical material from patients with symptoms not excluding WNF was studied. Donor blood sera samples were analyzed with the aim of detection of immune layer against WNV in population of Saratov Region. RESULTS: In 2010 WNV antigens were detected by EIA in 12 samples (7.1%) of mammal organ suspensions. In 2012 by using RT-PCR and EIA, markers of WNV were detected in 6 samples of bird brain suspensions (6.3%) and 1 sample of mammal organ suspension. Immune layer of population against WNV was 4% in 2011, 2.8% in 2012. In 2012 in 11 of 27 examined patients IgM against WNV in diagnostic titers and/or serconversion of IgG in paired sera were detected. In addition in 5 individuals virus RNA was detected in blood. Based on clinical, laboratory data and epidemiologic anamnesis 11 patients were diagnosed with WNF. CONCLUSION: The results obtained give evidence on the circulation of WNV on the territory of Saratov Region in 2010 - 2012. With the development of complications of WNF epidemiologic situation in 2012 an expansion of WNV areal onto the territory of the region took place and the process of formation of WNF natural foci is ongoing.