Objective of research: The purpose of our research was to study parasite fauna of salmonoid fishes from thelakeSobach’e (Putorana plateau) and to report its ecological and faunistic characteristics.

Material and methods: 88 specimens of salmonoid fishes (herring, siberian whitefish, round whitefish, arctic grayling and dominant species of char) were collected from thelakeSobach’e in July - August 2014. Collecting, fixation and cameral treatment were carried out using the standard method of Bykhovskaya-Pavlovskaya. Statistical treatment of the data was conducted using the Quantitative Parasitology 3.0 software.

Results and discussion: Data on parasite infestation of salmonoid fishes from thelakeSobach’e is provided. 29 parasite species (Myxosporea – 3, Monogenea – 2, Cestoda – 7, Trematoda – 7, Nematoda – 3, Acanthocephala – 4, Hirudinea – 1, Crustacea – 2) were found. Analysis of parasite distribution in their fish hosts was described. The lake has been classified as oligotrophic with the features of subfamilies Orthocladiinae and Pontoporane according to the concept of the parasitological typing of lakes presented by Rumyantsev E.A.

Objective of research: To study the species diversity of ticks in the north – eastern part ofUzbekistan: fauna, distribution patterns and ecology.

Materials and methods: Research samples were collected with the use of common parasitological methods [2, 3, 4]. Host animals were examined once a decade by collecting parasites from certain groups of farm and wild animals.

Results and discussion: 13 species of 6 tick genera discovered during the research period on the territory of the north - easternUzbekistan: Ixodes persulcatus, I. redikorzevi,I. crenulatus, Haemaphusalis caucasica, Boophilus calcaratus, Dermacentor pictus, D. daghestanicus, D. pavlovskyi, Rhipicephalis turanicus, H. asiaticum, H. detritum, H. anatolicum, H. plumbeum turanikum. Species B. salcaratus, H. asiaticum are distributed in all survey areas what confirms their high ecological flexibility. The extensity of infection of livestock with ticks is rather high - 51.3 - 52.3%. The infestation of synanthropic and wild animals ranged from 37.0 to 40.0%.

Objective of research: to provide the analysis of literature sources describing the in uence of host genes on genetic susceptibility to helminthiasis and the features of its pathogenesis. 

Results and discussion: all recent scienti c works dedicated to the in uence of host genes on genetic susceptibility to helminthiasis and the features of its pathogenesis were considered. The most important determinants of impact of host genes on genetic susceptibility to helminthiasis are gene polymorphisms TAP for echinococcosis, variants of genetic loci SM1 and SM2 for bilharziasis (schistosomiasis), and gene polymorphisms HLA for all three parasitic diseases described in this article.

Objective of research: to study the regional epizootology, species composition and bioecological features of development of causative agents of cattle hypodermatosis and elaboration of struggle measures against it in theChechenRepublic.

Materials and methods: Data on extensity and intensity of invasion, species composition of causative agents of cattle hypodermatosis, seasonal dynamics, larval approach to the surface of animal back (gadfly larvae deposited in animals' skin), time of the larval-pupal transformation (stages of larval development), treatment and prevention measures are provided in this article.

Results and discussion: This research has found that in the Chechen Republic the extensity of gadfly invasion was in the range 24,4% – 62,1%; the intensity of invasion was 9,8 – 24,0 larv./animal. Two gadfly species Hypoderma bovis De Geer and Hypoderma lineatum De Villers are causative agents of animal hypodermatosis. H. bovis is spread everywhere, H. lineatum - mainly in plain and piedmont of the republic. Gadfly flight in different natural-climatic zones of the republic is registered from the end of April until the middle of October.  Treatment and prevention measures continuously conducted for the whole livestock ( in spring against larvae of the 1st stage and in autumn - against larvae of the 2nd and 3rd development stages), taking into account ecological, phenological and epizootological situation in the region, may contribute to the full elimination of causative agents of hypodermatosis or their significant minimizing, reduction of economic damage to livestock of the republic.  Based on experimental data, the economically reasonable schedule of treatment and prevention measures has been created. 

Objective of research: The purpose of the study is to investigate the influence of Ligula intestinalis plerocercoids on linear growth of roach Rutilus rutilus in the Chivyrkuysky bay of thelakeBaikal.

Materials and methods. Roach was caught on a permanent station in the Monakhovo creek of Chivyrkuysky bay of thelakeBaikal at the same time interval (June 25-July 5) in 1997-2005. The analysis of roach infection with L. intestinalis plerocercoids was performed based on incomplete parasitological dissections of 807 host specimens at the age of 0+ to 10+. Standard body length (the distance from the tip of the snout to the anterior end of the caudal fin) was used to characterize the linear growth of roach.

Results and discussion. L. intestinalis plerocercoids wasn’t found out in underyearlings (0+) of roach. The host began to be infected with this tapeworm at the age of 1+. The maximum infection level with L. intestinalis plerocercoids was observed in roach at the age of 3+. That one was significantly reduced in the age of 4+. The infection level of roach with L. intestinalis continued to decrease in the next age groups, going down to a minimum at the age of 7+. The roach wasn’t infected with this tapeworm at the age of 8+–10+. A significant reduction of the infection level in the roach in the age classes 4+ and older after the maximum at the age of 3+ was probably associated with parasite-induced mortality of the host during the growth of the age group 3+ to 4+. A standard body length of roach specimens infected with L. intestinalis at the age of 1+ and 2+ was greater than that of uninfected ones. In contrast, the standard body length of the roach specimens infected with this tapeworm was less than that of uninfected ones in subsequent age classes (3 + -6 +). Differences of standard body length between roach specimens infected with L. intestinalis and uninfected ones were statistically significant in the above-mentioned age groups (1 + 6 +). The effect of L. intestinalis plerocercoids on the linear growth of the roach in Chivyrkuysky Bay of the lake Baikal was manifested in an increase of body length of infected host specimens compared to uninfected ones in young age groups (1+ and 2+) and, vice versa, in one’s decrease in age groups 3+–6 +. We proposed to call this effect "reversive".

Objective of research: Parasitic diseases of which helminthoses are the most dangerous, lead to decrease in livestock numbers, milk and meat production. Therefore, the important task is to develop highly effective broad-spectrum anthelmintics, optimal doses of their application and schedules for dehelmintization taking into account epizootological features of different helminthoses.

Materials and methods: Research was carried out at livestock farms of Bagrationovsky, Gvardeysky, Guryevsky, Zelenogradsky, Nesterovsky, Krasnoznamensky, Slavsky, Gusevsky, Nemansky, Prabdinsky, Polessky, Ozersky, Chernyakhovsky districts of theKaliningrad region. Some jobs were conducted at the Department of Zootechnics ofKaliningradStateTechnicalUniversity. 680 cattle and 370 sheep heads were investigated.

Results and discussion: Monieziasis is spread in all districts of theKaliningrad region, and causes significant economic damage to livestock.  In theKaliningrad region located in the area of over-moistening, oribatid mites appear on the soil surface in the first decade of April, then the increase in mite numbers is observed until July-August. At infestation of animals at the end of the pasture period, growth and development of helminths is slower than in spring and summer seasons. Preventive (pre-imaginal) dehelmintizations and efficient use of pastures are leading measures for the prevention of monieziasis in ruminants.

Objective of research: to study the nematode infestation of the sable and pine marten inWestern Siberia.

Materials and methods: Altogether 169 individuals of the sable and 18 – of the pine marten were investigated using the method of partial dissection of the gastrointestinal tract and lungs. Animals were caught according to the hunting license in 2009-2011 and 2014-2015, in 8 areas ofWestern Siberia from the south taiga to the northern forest-steppe.

Results and discussion: We have found four species of parasitic nematodes, two of which (Crenosoma petrovi, Filaroides martis) were localized in lungs and two species (Capillaria putorii, Strongyloides martis) – in the intestine of the sable and the pine marten. Prevalence of lung nematodes was 80 %, intestine nematodes – 40 %. Intensity of infestation ranged from 26 to 358 nematodes per animal. F. martis is the most pathogenic and most common helminth in martens inWestern Siberia. 53,3 % of pine martens and 26,5 % of sables were infected with this nematode species. Nematode S. martis is the most abundant in the intestine. In pine martens the extensity of invasion was 42,8 %, the abundance index– 8.29 helminths per animal; in sables - 9,1 % and 1.18, respectively. Pine martens were infected by F. martes and S. martis more than sables (p ˂ 0,05).  Prevalence increases in the direction from the North East (taiga) to the South West (sub-taiga), which determines the intensity of the helminthiases focus in biocenoses ofWestern Siberia. Infection of pine martens in the forest-steppe was not detected. In 2014–2015 compared with the previous study period (2009–2011) the extensity of invasion with intestinal nematodes increased by 1,5–2 times, and with highly pathogenic lung parasites – by 3 times. The increase in the helminth infestation may be explained by the growth of animal population density.

Objective of research. As deer are kept year-round on pasture (in summer in tundra in the northern coast of the Russian arctic; in winter – in forest-tundra and northern taiga), biogeocenosis and natural focality of most parasitic and infectious diseases were formed over the years. That should be considered when developing methods for combating them, and to determine the optimal timing of mass treatment and prevention measures.

Materials and methods. The question naturally arises, which living and nonliving components ensure pathogen survivability, contribute to the emergence and spread of infectious and invasive diseases. Each disease is characterized by specific factors requiring careful examination and generalization based on the study of clinical records and epizootic diseases in reindeer of the European North of Russia.

Results and discussion. Dominant diseases of reindeer in the European region ofNorthern Russia, requiring greater attention of veterinary experts and against which it is necessary to conduct a regular complex of veterinary, prevention and treatment measures are: anthrax, edemagenosis, cephenomiosis, necrobacillosis, echinococcosis, cysticercosis, rabies, leptospirosis, number of helminthoses (strongylatosis, monieziasis, echinococcosis, cysticercosis, etc.). This is a brucellosis-free region, and for many tens years no outbreaks of FMD were reported.  The vast majority of the tundra is located in the permafrost zone; the area is dotted with numerous canals, lakes, rivers, streams, marshes, between which in summer on shallow layered soil, grow bushes of willow, dwarf birch, berries, grass and lichen, the main food of deer. The fauna of the tundra is rich and diverse. Here live wolves, foxes, bears, rodents (lemmings, mice), rabbits, birds (geese, ducks, partridges, gulls) and other animals. In summer, "clouds" of midges (mosquitoes, midges, horseflies, flies) are flying in the air. In the region, there are still places virtually untouched by man.  However, in recent years, intensive industrial development of the region began to carry out exploration and extraction of oil, gas and other minerals. Oil and gas pipelines, roads, power lines are built which certainly cannot affect negatively the extremely vulnerable nature of the North. For example, reindeer moss trampled or torn down by moving offroaders can be restored only after 7-10 years. Summer season in the North is a very short period, there are usually few warm and sunny days. These negative factors lead to reduced pastures and do not contribute to the growth of the deer population, their health status and fatness.

Objective of research: The analysis of spatial distribution of ascariasis among the population in different regions of therepublic ofBelarus with respect to anthropological and cultural aspects. Investigations for regional differences in ascariasis conducted in theUSSR were focused rather on climatic, hygienic and economic factors and didn’t consider the causative role of cultural and anthropological factors in epidemiological process. The study is aimed at correlation of regional indices of ascariasis with the previously defined spatial historical gradient manifested inBelarus.

Materials and methods: The effect of social and cultural spatial gradient was assessed by comparison of difference in ascariasis morbidity between eastern and western regions ofBelarus. Thus, the effect of ethnic and anthropological spatial gradient was considered in comparison of epidemiological indices between theBrest region (south-western part ofBelarus) andVitebsk region (north-eastern part). The analysis was conducted with the historical perspective; the regional epidemiological statistics were provided for two periods 1970-1989 and 2000-2014. Regional statistical materials of therepublic ofBelarus presented in the annual reports of the national Ministry of Health were used as an empirical basis.

Results and discussion: The analysis showed, that the differentiation trend in distribution of ascariasis inBelarus correlates both with historical-cultural and anthropological spatial gradients. The identified pattern of regional differentiation allows to evaluate the complex effect of sociocultural and anthropogenic components on epidemiological features of ascariasis.

Object of study: Studies of lung helminths from various groups were performed. Elaboration of biological and taxonomic classification of these species has been proposed.

Materials and methods: 16 species from families Cervidae, Bovidae, Leporidae and humans were studied for lung helminths inRussia (South and central),Armenia,Bulgaria,Poland. The helminths found were studied using a scope of traditional and elaborated helminthological methods.

Results and discussion: In lungs of mammals studied 23 helminth species have been found including 1 of Taeniidae (Echinococcus granulosus), 4 of Dictyocaulidae and 18 of Protostrongylidae. We have divided species composition of these lung helminths into three biological groups. The first biological group included nematodes from Dictyocaulidae family. Life cycles of those helminths are monoxenous (they are geohelminths). The second group includes helminths from family Protostrongylidae. Their life cycles include intermediate hosts – land snails and so they are dixenous (biohelminths). The third group includes an agent of a quite dangerous zoonosis – Echinococcus granulosis larvae. These cestodes also develop per dixenous type, but their intermediate hosts are vertebrates with definitive hosts also vertebrate, mostly carnivores. Taxonomic classification for family Protostrongylidae haelminths is also proposed.

Objective of research: The study of eosinophilic reaction in blood at experimental dictycaulosis of young sheep and after providing the complex therapy.

Materials and methods: The research was conducted in August- September 2013at an experimental farm «Kurilovo» inPodolsk district ofMoscow region. Six mongrel lambs at 4–5 months of age, free from infection, and 18 lambs experimentally infected with Dictyocaulus filarial at gtye dose of 1000 larvae per head were investigated. 30 days after invasion, lambs were divided into 3 equal groups (6 head in each) and kept under conditions excluding the possibility of spontaneous invasion. Lambs of the first group free from infection, served as controls and did not receive the drug. Infected animas of the second group were not treated and served as controls. Lambs of the third group received Alben as 20% granulated powder at the dose of 5 mg a.i./kg (0,25 g of granules per10 kg of body weight); the fourth group of lambs received Alben at the same dose and subcutaneously T-activin at the dose of 2 mkg/kg once a day on the 1st , 3rd and 7th day of invasion, and В-activin at the dose of 5 mkg/kg intramusculary once a day during 5 days. Before the experiment and after 7, 15, 30 and 60 days of treatment, blood samples were taken from calves. Trilon B was used as anticoagulant. Blood eosinophil levels were measured by the standard method. 

Results and discussion: Persistent blood eosinophilia was determined at experimental dictycaulosis in lambs. The level of eosinophils cannot be fully restored by dehelmintization with Alben. The full restoration of the quantity of eosinophils in blood of infected lambs occurs after the complex therapy with Alben in combination with T and В-activin. 

Objective of research: to investigate the clinical features of acute opisthorchiasis in rabbits.

Materials and methods: Clinical evidence of acute opisthorchiasis in rabbits, laboratory blood tests.

Results and discussion: Skin lesions in the form of cracks and ulcers of various sizes in the neck, thoracic back and croup, mostly localized along the spine, were clinically identified in acute opisthorchiasis of rabbits. Weight loss within the first month was up to 300 –500 grams. Laboratory tests showed that one month later, the level of blood glucose in the infected animals was 3 times higher than in controls. Compared with the controls, a reduced number of red blood cells and hemoglobin level in animals of the experimental group was observed, leukopenia was determined. The blood coagulation time was significantly accelerated.

Objective of research: to present the actuality and novelty of application of fish and grass “rotation” because this allows to reveal new data on pond drainage planning which is the most effective in sanitation of the fish farm.

Materials and methods: To determine the most effective cycle for the summer drying of ponds, we studied ecological and epizootological features of fishing ponds, which had been used after drying within 1 and 5 years. As research object served 8 fish ponds: 4 drained ponds under crop (40 ha), 4 – overflowed (40 ha) and filled with one-year carps (2,5-З thousand ind./ha) and silver carps (1,2-1,4 thousand ind./ha).

Results and discussion: The results of comparative research on anti-epizootic efficacy of pond drying at different periodicity of 1 and 5 years with the use of fish and grass “rotation” are provided. Data on decreased invasion of fishes (carp, silver carp) by parasites, absence of causative agents of infection, improved blood indicators, increased fish production at annual pond drying (with the use of fish and grass “rotation”) compared with the pond drying of 5 year periodicity are presented. Advantages of economic efficacy of the annual frequency of pond drying are confirmed: twice increased commercial fish production; reduced expenses for purchase of food (own barley and wheat production), drugs, disinfectants, fertilizers that allow increasing economic revenue and making profit.

Objective of research: the sanitary-veterinary and economic evaluation of the disinfecting effect of different technologies applied for decontamination of livestock manure and sewage from invasive pathogens of pigs as well as for conversion of these wastes.

Materials and methods: The degree of contamination of liquid manure from pig farms with eggs and helminth larvae, cysts and oocysts of parasitic protozoa, was studied on the samples collected once a month at farms of theMoscow region, and once every two months at farms of theRepublic ofMordovia. Sampling, transportation and investigation of samples were carried out by the method of A. Cherepanov (1972). Samples were taken in the morning at 3-5 points using IMOP sampler 1000. At the sampling point, an inventory was created where the date, location, selection point and its sample volume were indicated. To prevent the development of microflora in the samples, a certain amount of preserving agent was added. When sampling solid manure fraction from the surface, middle and lower level, manure mass was selected horizontally at each level from 3-5 points, thoroughly mixed, then the averaged sample (1.0 kg) was placed in a plastic bag. To confirm the viability of helminth eggs detected by coproovoscopic examinations, eggs were transferred with a micropipette into Petri dishes and cultured in an thermostat at a temperature 26˚C in a humid environment, periodically aerating and observing the development of the embryo. Comparative assessment of the effectiveness of the treatment facilities in selected pig farms was performed by comparing the number of invasive elements in1 liter of liquid manure entering and flowing out of the treatment facilities.

Results and discussion: at all three selected pig farms, the most intense infections with helminth eggs, cysts and oocysts parasitic protozoa were found in raw sewage, what indicates a lack of effectiveness of anti-parasitic measures at the farm.  JSC "Mordovia bacon" with 54 thousand pig heads a year is the only one of three inspected farms, where liquid manure is separated into fractions, followed by disinfestation of solid fraction on concrete pads with further application of manure as an organic fertilizer. Due to mechanical separation of liquid manure into fractions applied at this farm, the number of parasitic elements of internal parasites of pigs (eggs of Ascaris, trihotsefal, esophagitis, coccidia oocysts and cysts balantidiums) in1 kg solid fraction was 586ind. The efficiency of decontamination of liquid manure from parasitic elements, taking into account this treatment method was 53,6-73,4%. Biothermal decontamination of solid fraction of manure piles is achieved within 3-5 months (100%), depending on the season and used in fields as organic fertilizer.

Objective of research: the study on tolerability and therapeutic efficacy of the complex drug Helmintal produced on the basis of two ingredients moxidectin and praziquantel.

Materials and methods: In our research, we used four drug modifications: for cats and kittens weighting less than4 kg (moxidectin 0.4 mg and praziquantel 10 mg); for cats - more than4 kg (moxidectin 1.6 mg and praziquantel 40 mg); for dogs and puppies - less than10 kg (moxidectin 1 mg and praziquantel 25 mg); for dogs - more than10 kg (moxidectin 5 mg and praziquantel 125 mg.) To study the effect of the drug on the organism, three groups of clinically healthy animals were formed (5 animals per group): dogs 1 - 2 years of age with the body mass 18 -20 kg; puppies 3 - 5 weeks of age weighting 0.8 -1 kg; cats 1 - 2 years of age weighting 3 -5 kg; kittens 6 - 8 weeks of age with the body mass 0.6 -0.8 kg. The drug was given to animals orally once a day in the morning within 7 days in the following doses: the first experimental group - 0.4 mg moxidectin and praziquantel 10 mg per1 kg of body weight (double therapeutic dose); the second group - moxidectin 1.0 mg and praziquantel 25 mg per1 kg of body weight (five-fold therapeutic dose); the third group served as controls - the drug was not used. During the experiment, animals were monitored daily, their general health status, behavior, appetite were observed, weight and body temperature controlled. Before and 15 and 30 days after the beginning of the drug taking, several morphological and biochemical parameters of blood and urine were investigated. The study of the anthelmintic efficacy of the drug was carried out on the basis of veterinary clinics inMoscow andMoscow region. Altogether 205 cats and 209 dogs spontaneously infected were chosen for the experiment. The diagnosis and the drug efficacy were confirmed based on the clinical picture and on Fulleborn's method used for detection of helminth eggs in animal's feces followed by differentiation.

Results and discussion: During the study on the drug tolerance it was found that the general status, mass and the body temperature of animals from experimental groups did not significantly differ from controls. Morphological and biochemical parameters of blood and urine in all animals from experimental and control groups did not differ significantly and were within the physiological norm before and after treatment. Thus, the research allows to conclude that the drug applied within 7 days at double and five-fold therapeutic doses has no adverse effect on dogs, puppies, cats and kittens. Most sick animals used in the experiment on the effectiveness of the drug, were emaciated, listless, their fur was ruffled, mucous membranes were pale; they suffered from anal itching, diarrhea and fecal retention. The drug was given after diagnosis; many dogs and cats ate it themselves, and other had no problems with eating pills due to their small size and pleasant taste. When applying the drug and throughout the experiment, no side effects and complications were observed in all animals. 10 and 20 days after giving the drug, its efficacy in the treatment of nematodosis and cestodosis of adult dogs cats as well as kittens and puppies was 100%.

In this article is shortly described methods of study of helminth fauna of mammals in protected areas. Methods and results that kind of study are depicted by the example of researches which were carried out in the Central-Chernozem state nature reserve inKurskoblast. These methodical recommendations intended for researchers of reserves, national parks, parasitologists, mammalogists and broad zoologists.

Objective of research: to study distribution and features of epizootic process at canine babesiosis in the central area of theRussian Federation as well as improvement of diagnostics, treatment and prevention measures.

Materials and methods: Definition of species composition and number of ticks (Ixodidae) on dogs. Statistical analysis of veterinary reports from regional veterinary stations of theRyazan region. Laboratory microscopic and serological diagnostic test for canine babesiosis.

Results and discussion: Seasonal dynamics of activity of ixodid tick Dermacentor reticulates (April — June and August — October); maximal extensity of invasion with Babesia spp. (75%); average level of parasitemia in acute and super-sharp form of babesiosis in spring and autumn; clinical parameters of non-sterile immunity in adult and young animals; dependence of the degree of the severity of disease on the age of dogs were determined. The maximum parasitemia was observed in young (7-23%) and old (6-30%) animals. The average parasitemia was determined in dogs at the age of 3-7 years were 5-11%. The results of hematological and biochemical research revealed that severe acute canine babesiosis is characterized by erythropenia, decreased level of hemoglobin, haematocrit and thrombocytes, leukocytosis, increased level blood bilirubin (by 3-25 times), urea (1,5-5) and creatinine (1,2-3), reduced glucose level (up to 50%). In babesiosis of light and mild severity, the above-mentioned changes of hematological and biochemical parameters in dogs were not significant. Latent canine babesiosis might be diagnosed by serological test (RAHА) on antibodies to Babesia spp. High efficiency of domestic drugs Babesan (EE = 96,5%), Forticarb (EE = 93,3%), Piro-Stop (EE = 90,9%), Veriben (EE = 82,3%), Neosidin (EE = 75%) for babesiosis in dogs was determined. The drug Emidonol which has antioxydantic and antihypocsantic properties and was used within 5-7 days for dog treatment, promotes prevention of complications in the form of heart and respiratory failure, and reduction of recovery time. Efficiency of the drug «Bars spot-on» (containing ivermectin) applied against ixodid ticks was detected. Repellent efficiency of the essential oil-based collars «Bar», «Fitodoc» and «Chetyre s hvosticom» used against ixodidosis of dogs, was confirmed, the duration of their action is from 160 to 180 days.

Objective of research: to perform the analysis of long-term (15 annum) dynamics of Bithyniidae snails infected by trematode parthenites from the Chany Lake, the biggest lake in the south of Western Siberia

Materials and methods: The Bithyniidae snails examined in the lake-river systemsChanyLake in 1994-2013 (in the middle reaches and in the estuary of theKargatRiver) and in theZolotyeRossypiBay and theMalyeChanyLake. The Bithyniidae snails were collected from May to September (twice in any ten days) by hand from 4–6 plots of0.25 m2 at a depth of 0.1–0.7 m. In total, 8,316Bithynia troscheli (Paasch, 1842) and 766 В. tentaculata (L., 1758) were examined. Identification of parthenitae trematode was based on observation when mature cercariae were capable of leaving the shell of the host snail on their own.

Results and discussion: In Bithyniidae snails, we found parthenites from trematodes from 12 families Cyathocotylidae Mühling, 1898 Poche, 1925; Prosthоgonimidae Luhe, 1909; Pleurogenetidae Looss, 1898; Lecithodendriidae Odhner, 1911; Microphallidae (Ward, 1901) Travassos, 1920; Plagiorchiidae Lühe, 1901 Echinostomatidae (Looss 1899) Dietz, 1909 Odhner 1910); Psilostomidae (Looss 1900) Odhner 1913; Notocotylidae Luhe, 1909; Monorchiidae Odhner, 1911; Cyclocoelidae Kossack, 1911 и Opisthorchidae (Lass, 1899) Braun, 1901. 

The prevalence of bithyniid snails infected by trematode parthenites varied from 1,6% to 24,1% in different years.

The double infection by trematode parthenites was found in 0,96% bithyniid snails from estuary of theKargatRiver; 4,45% in theMalyeChanyLake, and 26,6%, in theZolotyeRossypiBay. The cercariae of Opisthorchidae family in four annum of the fifteen detected. The prevalence of bithyniid snails infected by trematode parthenites from Opisthorchis felineus (Rivolta, 1884) and Metorchis bilis (Braun, 1890) was observed inChanyLakesystems for the first time. Both species (O. felineus and M. bilis) of trematodes have danger to human health and causes very dangerous disease, opisthorchiasis and metorchiasis.