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The infrapopulation of the Echinostoma caproni partenites has a development of prolong character (Ataev et al, 2005). However, in laboratory conditions, Biomphalaria molluscs infested with this parasite die within 1—3 weeks after the beginning of cercariae emission. It has been suggested that autoinvasion of the mollusc host with the cercariae, which use it as second intermediate host, is the cause of this phenomenon. Studying the dynamics of metacercariae accumulation in the host (both infected and non-infected with the Echinostoma caproni rediae) and experiments where quantity of cercariae around molluscs reduced by different ways, confirmed this hypothesis. Evidently, pathogenicity of metacercariae for molluscs is lesser in nature, because the concentration of cercariae reduces to the values, which do not result in lethal effect: some part of cercariae dies, but another part uses other animals as a host (Haas, 2000).

The pygmaeus-species group is composed of close related species from the genus Microphallus in which metacercariae develop inside daughter sporocysts without encystment. Infection of periwinkles Littorina (Neritrema) spp. with intramolluscan stages of a new species of this group (Microphallus kurilensis sp. nov.) was recorded on the coasts of Sakhalin and Kuril islands, north of the Sea of Okhotsk and Chukchi Peninsula (the Bering Sea). Application of molecular methods allowed us to establish that M. kurilensis metacercariae are conspecific with one of the morphotypes of microphallid adults obtained from the intestine of the Pacific common eider (Somateria mollissima v-nigrum), which was shot in the north of the Sea of Okhotsk (Galaktionov, Olson, and Blasco-Costa, in press). The adults of the same morphotype were recorded in the Pacific common eider from the northwestern part of the Bering Sea (Chukchi Peninsula). In the course of experimental infection of the slaty-backed gull Larus schistisagus chicks with metacercariae of M. kurilensis, few microphallid adults were obtained. These adults were identical in their morphology with specimens of the microphallid morphotype from the Pacific common eider, which had been identified as M. kurilensis based on molecular data. Morphological description of metacercaria and adult of M. kurilensis and list of their differences from the same developmental stages of other species from pygmaeus-group are provided. It is concluded that M. kurilensis is transmitted in the host system including periwinkle Littorina (Neritrema) and seaducks (predominately, Pacific common eider). Most probably, distribution of M. kurilensis is not limited by the north Asiatic coast but expanded to the North American coast of the Pacific Ocean.

Haploid complement of Phyllodistomum umblae ex baikal white fish from Lake Baikal consists of 8 chromosomes (6 metacentrics and 2 submetacentrics). The significant difference is observed in the ratio of acrocentrics and metacentrics in the haploid set of chromosomes between isolated populations of P. umblae from Baikal region and from Chukotka. The hypothesis is advanced that these chromosome populations may be chromosome races of P. umblae.

A review of the fauna of trematodes from the family Dicrocoeliidae parasitizing animals in Vietnam has been conducted. According to original and literature data, 57 trematode species from 15 genera were recorded. Data on hosts, localization, and distribution of all these species in the territory of Vietnam are given.

Cattle of Dagestan are infested with several nematode species from the suborders Spirurata and Filariata, and extensiveness of the invasion depends greatly on the altitude above sea level. Level of infestation with Thelazia rhodesi, Th. gulosa, and Th. skrjabini is 38% in plains, 20% in submontane, and 5% in mountain zone. The same tendency is observed for the species Gongylonema pulchrum — 45, 22, and 10%, respectively. Infestation with Setaria labiato-papillosa is 27.3% on average. Infestation with Onchocerca gutturosa and O. lienalis is 11% in plains and 3% in mountain and submontane zones; infestation with Stephanofdaria assamensis and S. stilesi in these zones is 18 and %, respectively. In mountain localities situated higher than 1000 m a. s. l. only G. pulchrum is occurred.

Description a lecithodendroid cercaria, Cercaria rhionica II (Galaktionov, Dobrovolskij, 1987) (Plagiorchiida: Lecithodendroidea) from the freshwater mollusc Melanopsis praemorsa (L.) from the Kura River in Azerbaijan is given, including figures, morphological data, and differential diagnosis. Special attention is paid to the structure of excretory system, secretory apparatus, tegument armature, inclusions in parenchyma, topography of sensilla (chaetotaxy) and some peculiarities of cercarian biology. The paper also includes some data on the life cycle of the parasite, including figures and descriptions of experimentally obtained cysts and metacercariae.

In our study, Borrelia were revealed in the taiga ticks Ixodes persulcatus collected on vegetation by flagging, as well as in the ticks removed from the people who asked for help in the vaccination center located in the Novosibirsk Scientific Center of the Siberian Branch of Russian Academy of Science (NS SB RAS). By the isolation of Borrelia on BSK-H medum, the occurrence of B. garinii, B. afzelii, and B. miyamotoi was established in the territory of NSC. B. miyamotoi isolates were unstable and lost their ability to growth in later passages. DNA of the same three species оf Borrelia was detected by PCR in the samples of ticks, both collected on vegetation by flagging and removed from humans. DNA of B. garinii was recorded most often; DNA of B. afzelii was less frequent; and the least number of positive samples was shown for B. miyamotoi. In the ticks collected on vegetation by flagging, DNA of B. garinii was found in 38.6%, B. afzelii in 9. %, and B. miyamotoi in 3. % of samples. In the ticks removed from people, number of positive samples was lesser; so, DNA of B. garinii was detected in 24.2%, B. afzelii in 6.9%, and B. miyamotoi in 5.6% of samples. Mixed infection with two Borrelia species was recorded, and DNA of B. miyamotoi more often detected simultaneously with DNA of B. garinii.

Five possible evolutionary scenarios of the higher acariform mites from the cohort Parasitengona are proposed on the basis of the detailed examination of anatomy of the excretory organ and midgut in the representatives of terrestrial mite families Trombiculidae and Microtrombidiidae, and in freshwater mite families Teutoniidae and Pionidae, on different developmental stages including parasitic larva. These scenarios explain possible ways of evolutionary transformation within the Parasitengona from one or several ancestor with the open digestive tract.

Summary is absent.