[(INFESTATION OF FISHES OF THE FAMILY CYPRINIDAE IN THE FOCI OF TREMATODES OF THE ECOSYSTEM OF THE BELAYA RIVER (THE REPUBLIC OF BASHKORTOSTAN)].

In the ecosystem of the Belaya River, fishes of the family Cyprinidae were infected with three epidemically important species oftrematodes of the family Opisthorchidae: Opisthorchisfelineus, Metorchis bilis, and Pseudamphistomum truncatumn. No biotopes of mollusks of the genus Codiella were detected. The contamination of underyearlings with-Ofelineus and M.bilis metacercariae indicates that there are cores of opisthorchiasis and metorchiasis (M.bifis) foci in the ecosystem of the lower course of the river. The presence of biotopes of the genus Bithynia mollusks, the first intermediate host.for P. truncatum, in the waters, but the absence of fishes infected with P.truncatum metacercariae among the examined under- yearlings may lead to the conclusion that there are no cores of pseudamphistomiasis foci. Infestation of onein 97 older individual muvarica (Albumus alburnus) with trematode metacercariae is evidence of its infection outside the floodplain river ecosystems of the Belaya River and subsequent migration of the fish into the lowerreaches of the river, where a barren zone of a pseudamphistomiass focus is formed. In this ecosystem there is a risk of human infection with epidemically important species of trematodes of the family Opisthorchidae (O.felineus, M.bifis, and P.truncatum)-when eating the fish caught in the river, its tributaries, and floodplain waterbodies. When identifying the metacercariae and detecting the natural foci of trematodes, it is necessary to take into account the fact that the fishes of the family Cyprinidae in the river ecosystem have four types of Opisthorchis metacercariae (after D.A.Razmashkin).

[EPIZOOTOLOGICAL CHARACTERIZATION OF TREMATODIASIS FOCI IN THE ECOSYSTEM OF THE AMUR RIVER IN THE KHABAROVSK TERRITORY].

Investigations were conducted in late June to early June 2013. The population density of mollusks of the genus Juga in the shoreline and littoral covered by meadow waters was 10 to 30 specimens/m2; there were solitary specimens of the genus Parafossarulus. Fourteen out of 39 fish species were invaded by metacercariae of Clonorchis. Manchurian spiny loaches (Leptobotia) and Light's bitterling (Rhodeus lighti) are first registered to be hosts of Clonorchis. The metacercariae of Metagonimus yokogawai were detected in silver carp (Hypophthalmichthys molitrix) and those of Nanophyetus salmincola schikhobalowi were in the kidneys, fin muscles, and gills of taimen (Hucho) and lenok (Brachymystax lenok) from the Khor River. The invasion rate for the taimen was greater than 1000 metacercariae and that for the lenok was not more than 720 metacercariae per fish.

[Epizootiological characteristics of clonorchiasis foci in the Amur River ecosystem in the Jewish autonomic region].

Malacofaunal and ichthyoparasitological studies were conducted in the floodplain-river ecosystem in the middle course of the Amur River. The studies covered its channels and tributaries, such as Big and Small Bira, Bidzhan, In, and Vertoprashikha Rivers, in the Birobidzhan, Leninskoye, and Smidovich districts of the Jewish Autonomic Region in the second half of August 2011. It was established that there were biotopes of the mollusk Parafossalurus manchouricus, the first intermediate host of Clonorchis sinensis, in the exosystems of the In, Bira, and Bidzhan Rivers. Sporadic P. manchouricus specimens were found in the Bidzhan channel in the vicinity of its estuary and on the flooded bank of the In River. The bay of the Bira River (the town of Birobidzhan) exhibited a biotope of P. manchouricus with a mollusk population density of 180 to 300 specimens/m2. Seven of 16 examined fish species showed metacercariae of Clonorchis. Among them there were not only Cyprinidae, but also representatives of other families and orders. The two-year-olds of orca-skripuns (Pseudobagrus fulvidraco), orca-whips (Tachysyrus ussuriensis), and Brazhnikov's orsas (Liocassis braschnikowi) were infected with C. sinensis metacercariae. Clonorchis metacercariae were first detected in Amur sleepers (Percottus glehni). This fish species has not been heretofore recorded as the second intermediate host ofC. sinensis. The highest invasion extent for C. sinensis metacercariae was revealed in Amur bitterlings (Rhodeus sericeus) born during the current year. In the biotopes ofdifferent water reservoirs, it changed from 10.0 to 48.0%. In 4 of 6 water reservoirs, Amur bitterlings were found to have larvae of this species of trematodes. The invasion rates were in the range from 1 to 4 metacercariae per fish. Only in individual cases, they were as great as 28 parasitic larvae per fish.

[Fish infection with Opisthorchis larvae in Russia and some contiguous countries (by the materials of the "Cadaster of opisthorchis infection foci in Russia in 1994"]. / Zarazhennost' ryb lichinkami vozbuditelia opistorkhoza na territorii Rossii i nekotorykh sopredel'nykh stran (Po materialam "Kadastra ochagov opistorkhoza Rossii, 1994").

A cadastre of opisthorchiasis foci with places under study and specious fish invasion with larvae of this helminthiasis has been first drawn up. Opisthorchis larvae have been found to be recorded in 23 species and 2 subspecies of the Cyprinidae family and 1 species of the Cobitidae family. The cadastre permits the areas epidemiologically hazardous due to opisthorchiasis to be determined. The data on fish species-specific infection in different river basins may render a great deal of aid to sanitary-and-epidemiological surveillance workers in implementing preventive measures in specific regions.

[Low-temperature regimens for the decontamination of fish of the larvae of Opisthorchis]. / Nizkotemperaturnye rezhimy obezzarazhivaniia ryby ot lichinok opistorkhisa.

It has been established experimentally that the Opisthorchis metacercaria in fish muscles were killed at -28 degrees S in 15-20 h., at -35 degrees C in 8 h. and at -40 degrees C in 2 h. The period of fish freezing becomes much longer when it is stored in snow-covered heaps, which may be the cause of Opisthorchis invasion of wild and domestic carnivorous animals.

[Infection and invasion of humans in the Yamal Peninsula]. / Infektsii i invazii cheloveka na poluostrove Iamal.

The helminthic fauna of vertebrates in the Yamal peninsula consists of 61 species: of them 2 species are monogenic, 6 are trematodes, 29 are cestodes, and 24 are nematodes. Twelve species of the 4 are antroponoses and 8 are zoonoses which may parasite on human beings. Human infection with some zoonoses is due to local habits of eating raw or undercooked meat of wild animals, domestic deers, and fish. These helminthic diseases include trichinosis, taeniasis, opisthorchiasis, diphyllobothriasis. On contacting with dogs and Arctic foxes, the population is infected with echinococciasis, alveococciasis, toxoplasmosis. The foci of brucellosis, anthrax, tularemia, leptospirosis, rickettsioses, rabies, and toxoplasmosis were notified in the Yamal peninsula. Intensive migration of the population contributes to the importation of new species of causative agents to the peninsula and to the deterioration of the situation of endemic invasions and infections. Thus, in-depth study of parasitic and natural focus-related diseases in this region becomes partially urgent now.