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For several years this pathogenic carp parasite has been cultivated on carp in tanks. Water temperature from 10 to 12°C, pH from 6.7 to 8.75, ammonia nitrogen no more than 6 mg/l, and oxygen from 5 to 6 mg/l were observed to be optimal for maintaining the host-parasite system. Pathological changes in the carp organism under the effect of I. multifiliis occur at the intensity of over 100 Ciliata per fish.

The paper reports new data on morphological content and blood parameters of big-mouthed buffalo at its infection with I. multifiliis. Identification of leukocytes was done according to the classification suggested by N.Т. Ivanova. Absolute lymphopenia, abundant promyelocytes in peripheral blood, shift to the left of the neutrophylic series, changes in the morphology of blood cells were observed during the disease.

404 specimens of 32 fish species were obtained off the southwest coast of Africa (the Namibia region). 6 trichodinid species were found on the gills of 5 fish species: Trichodina multidentis Laird, 1953 and T. oligocotti Lom, 1970 on Genypterus capensis, Trichodina frequentis G. Stein, 1979 on Merluccius capensis, (?) Trichodina ovonucleata Raabe, 1958 on Pterothrissus belloci and Trichodina sp. on Chelidonichthys hirundo. New data have allowed to supplement the scarce information on marine trichodinids of the southern hemisphere, to enlarge the host list of the previously described trichodinid species, and to obtain the additional material on the intraspecific variability of marine trichodinids.

Electron microscope studies of spherical intranuclear inclusions (II) of Entamoeba histolytica trophozoites of two strains, which were maintained in polyxenous culture for different periods of time, were carried out. Data on the number of II in different individuals and in different strains are given. The structure of II whose external layer consists of electron dence material and resembles morphologically peripheral chromatin of the amoeba's nucleus, an analogy of nucleolus chromatin of cells of other eucariots, is considered. Inside this layer some II have annular filaments about 9 nm thick rolled up spherically around the central zone of II. Comparison of results obtained and literary data suggests that the dynamic structure of II in question reflects a number of biosynthetic processes on the basis of annular extrachromosomal DNA of exogenic origin.

Polypodium is an ancient species in the Amur River. The rate of the infection of Acipenser baeri schrenki (Brandt) with Polypodium is 23.3% , the intensiveness is 15, i. e. 1237 Polypodium stolons from eggs of a sturgeon female. Coefficient of elimination is E. E=N/IP X 103, where N is the number of eggs with Polypodium stolons, IP is individual fecundity. This exponent for sturgeon is within an interval of 0.5 to 6.5, 2.2 on the average. The rate of Polypodium infection for Huso dauricus Georgi is 42.8% , the intensiveness is 83, i. e. 4356 parasites from eggs of a kaluga female. E is within an interval of 0.11 to 6.45, 1.9 on the average. From the point of view of sturgeons abundance dynamics Polypodium is a factor of elimination and this may be about 1130 sturgeons (11 t) and about 900 specimens of kaluga (45 t) per year.

A comparative efficiency of different regimes for infecting laboratory animals has been determined in order to find out optimal conditions under which an experimental model of intestinal schistosomiasis (infection with Schistosoma mansoni) can be maintained. When evaluating the results of laboratory definitive hosts infection we took into account the character of Schistosoma distribution in animals, which with high probability rate was modelled by means of negative binomial distribution. The main parameters of this distribution were used for determination of effective doses and methods of animals infection alongside with generally accepted indices of infection rate and intensiveness. Analysis of the data obtained has shown that the infection of 150 cercarians per mouse and 200 cercarians per golden and striped hairy-footed hamster by their subcutaneous administration creates optimal density of parasites in the host. Results of investigations have shown that striped hairy-footed hamsters can be used as definitive hosts of Schistosoma.

A role played by different age fishes in the formation of the helminth's ecological niche was assessed by analysing the infection prevalence and intensity and frequency distribution of the trematode (Bunodera luciopercae) number. Perch individuals of different size-age groups were shown to have seasonal and functional characteristics in maintaining spatial structure of the parasite population.

In children and adults Ixodes persulcatus adheres mostly often to axillary space, neck, anterior surface of the trunk and comparatively seldom to extremities in distal direction. Rather often in children the tick adheres to the head; with age the strength of adhering to the axillary space increases. The topography of adhering of I. persulcatus is closely associated with the character of activities and clothes of the population, ecological characters of the tick, size, anatomical, hystological and physiological properties of the man's organism in child's, juvenile and adult age, and weather-climatic conditions.

12744 ectoparasites (3 species of ixodid ticks, 10 species of gamasid mites and 10 species of fleas) were collected from 422 squirrels within 5 years of work in Sykhote-Alyn Nature Reserve. During warm period of the year most abundant on squirrel were the tick Ixodes persulcatus and the flea Ceratophyllus (M.) indages, in winter — the flea Tarsopsylla octodecimdentata. The infection of squirrel with gamasid mites is low. The dependence was found between the abundance of I. persulcatus larvae and the infection of squirrel with nymphs of this tick the next year. Preimaginal phases of I. persulcatus and the flea С. (M.) indages are connected with mobile part of the population, adult males, and T. octodecimdentata with less mobile adult females and young animals.

Breeding places of 10 species of tabanids from southern and central regions of the Tomsk district were studied. They are connected with the Ob river, its tributaries Tom and Chulym, with the Baksa, Kirgizka, Chernaja and Ushaika rivers, flood-plain waterbodies, meadow lowlands, forest bogged up areas and with water bodies near animal breeding farms. The average density of larvae is 7.3 spec./m². Most abundant were members of the genus Hybomitra (54.4%) and Tabanus (38.4%). The density of larvae depends on the time of their collection and their generic belonging.

Information on the first find of ellobiopsids in euphausiids of the Barents Sea is given. These data extend essentially a well-known region of inhabitation of these parasites.

A new species of microsporidians of the genus Gurleya from cells of cross-striated musculature of Palaemon elegans is described. Merogony is accompanied by the formation of a chain of mononuclear individuals in a number divisible by 3. Sporonts form tetranuclear cells which turn into pansporoblasts 4.0—5.0 µ in diameter. Spores are ovoid, 3.5—3.7 x 2.3—2.5 µ, thick-walled. Polaroplast occupies more than a half of the spore's length, posterior vacuole its 1/5, nuclear substance is in the posterior third of the spore. The new species differs from other species of the genus Gurleya in the size and shape of spores. The name has been given according to the place of its find.

The nervous system of the Prosorhynchus squamatus was studied by cholinesterase method. It includes 3 pairs of the longtitudinal trunks extending from the anterior to the posterior end of the body, the pair of the anterior trunks which goes from the brain to the proboscis, and 10 or 9 ring comissures. The proboscis is innervated by the anterior/portions of the longtitudinal trunks connected with the proboscis ring comissure, and by the anterior trunks. The pharynx is supplied with 2 ring nerves at its proximal and distal ends which are connected with 4 meridional nerves. The pair of pharingeal nerves branching off from the ventral trunks joins the proximal ring nerve, the distal ring nerve is connected with the 7-th ring comissures of the body. Id comparison to the other studied trematodes, the nervous system of Prosorhynchus may be considered of a relatively primitive type.

A new species Dactylogyrus turaliensis from Rutilus rutilus caspicus is described. The new species differs from the close species D. crucifer in size and shape of chitinoid formations by 6 characters. Its distribution seems to be limited by the Aral-Caspian basin.

The paper deals with infection of Meriones (M.) tamariscinus Pallas, 1773 caused by Rhabditis strongyloides Schn., 1866 first recorded in the USSR. The clinical picture of the disease is described and data of pathoanatomical autopsy of dead animals are given. The way of infection of the animals in nature and in laboratory conditions is suggested. Under favourable conditions domestic animals can be infected with R. strongyloides too.

Summary is absent.

Summary is absent.

Summary is absent.