The epidemiological significance of parasites of fishes in the Volga-Caspian fishery subdistrict (Astrakhan region)

Introduction. The epidemiological situation of parasitic diseases among the population of the Volga-Caspian fishery subdistrict within the Astrakhan region continues to be stressful. To cancel or prolong the restrictions on biohelminthoses in the region, it is necessary to conduct regular studies on the parasitic purity of fish and fish raw materials. Material and methods. In accordance with methods generally accepted in parasitology, in the period of 2013-2017, 7,671 mature specimens of thirteen species of fish of five families (carps, pikes, sheatfishes, perches, herrings) were examined. Results. In the parasitic fauna of all types of hydrobionts examined there were sanitary-significant parasites, represented by eight types of systematic groups: nematodes (Anisakis schupakovi, Contracaecum bidentat, Estrongylides excisus), trematodes (Apophallus muehlingi, Rossicotr.ema donutses), acanthocephalans (Corynosoma strumosum). The dominant group in prevalence in the population of the Volga fish were roundworms, small - acanthocephalus. The maximum quantitative indices were characterized by trematodes, the number of which in the single fish amounted to thousands. Discussion. The level of infestation of pike, catfish, bream, carp, pike-perch, perch, white bream, rud, roach, Caspian roach, sichel, Caspian anadromous shad, blue bream, parasites dangerous to humans has remained relatively stable for a number of years. The majority of fish in the eastern part of the delta (with respect to the western part) have a higher percentage of infected individuals, and therefore, aquatic animals caught in the first specified area should be subjected to more thorough veterinary examination when preparing it for sale to the population. Conclusion. The data on the annual invasions of fish and people (along with other warm-blooded animals) with epidemiologically significant parasites indicate the active functioning of natural foci of apophallosis, rosicotremosis, opisthorchiasis, pevdoamphistomosis, anizakiosis, contratsekoleza, eustrongilidosis, and corynozomosis in the Volga delta. For the prevention of biohelminthoses, it is necessary, in addition to state control (ensuring proper product quality), to establish a direct informational notification of the population in order to clarify the importance of the issue of parasitic invasions transmitted through fish.

The epidemiological significance of parasites of fishes in the Volga-Caspian fishery subdistrict (Astrakhan region)

Introduction. The epidemiological situation of parasitic diseases among the population of the Volga-Caspian fishery subdistrict within the Astrakhan region continues to be stressful. To cancel or prolong the restrictions on biohelminthoses in the region, it is necessary to conduct regular studies on the parasitic purity of fish and fish raw materials. Material and methods. In accordance with methods generally accepted in parasitology, in the period of 2013-2017, 7,671 mature specimens of thirteen species of fish of five families (carps, pikes, sheatfishes, perches, herrings) were examined. Results. In the parasitic fauna of all types of hydrobionts examined there were sanitary-significant parasites, represented by eight types of systematic groups: nematodes (Anisakis schupakovi, Contracaecum bidentat, Estrongylides excisus), trematodes (Apophallus muehlingi, Rossicotr.ema donutses), acanthocephalans (Corynosoma strumosum). The dominant group in prevalence in the population of the Volga fish were roundworms, small - acanthocephalus. The maximum quantitative indices were characterized by trematodes, the number of which in the single fish amounted to thousands. Discussion. The level of infestation of pike, catfish, bream, carp, pike-perch, perch, white bream, rud, roach, Caspian roach, sichel, Caspian anadromous shad, blue bream, parasites dangerous to humans has remained relatively stable for a number of years. The majority of fish in the eastern part of the delta (with respect to the western part) have a higher percentage of infected individuals, and therefore, aquatic animals caught in the first specified area should be subjected to more thorough veterinary examination when preparing it for sale to the population. Conclusion. The data on the annual invasions of fish and people (along with other warm-blooded animals) with epidemiologically significant parasites indicate the active functioning of natural foci of apophallosis, rosicotremosis, opisthorchiasis, pevdoamphistomosis, anizakiosis, contratsekoleza, eustrongilidosis, and corynozomosis in the Volga delta. For the prevention of biohelminthoses, it is necessary, in addition to state control (ensuring proper product quality), to establish a direct informational notification of the population in order to clarify the importance of the issue of parasitic invasions transmitted through fish.

Galactooligosaccharide effects as prebiotic on intestinal microbiota of different fish species

Manipulation of the gut microbiota toward potentially beneficial bacteria (probiotics) has beneficial effects on fish physiology and health. The effects of prebiotics on gut microbiota are species specific. The present study aimed at investigation of the effects of galactooligosaccharide (GOS) as prebiotic on intestinal microbiota of Caspian roach and Caspian white fish fingerlings. which are among the most economically valuable species in the Caspian Sea. The study was conducted in a completely randomized design with two set of experiment each of them include three treatments in triplicates in which 0 (control), 1 and 2% GOS were used in diet for 6 weeks. At the end of the period, changes in the intestinal microbiota, including total bacterial count, lactic acid count and lactic acid bacteria (LAB) levels and dominance of LAB in the intestinal microbiota, were measured by culture-based method. Dietary GOS had no significant effect on total bacterial count in both species (P < 0.05). The LAB levels in the intestinal microbiota in the treatments fed with prebiotics was significantly higher than the control group (P < 0.05). LAB bacteria showed the highest increase and dominance in treatments fed with 2% GOS. Also, the highest ratio of lactic acid bacteria to the total number of viable bacteria was observed in the treatment with 2% GOS treatment (P < 0.05). The results of this study indicated the possibility of alterations in the bacterial communities of Caspian roach and Caspian white fish fingerlings gut toward beneficial bacterial communities using GOS as prebiotic.

Fishes from the Volga-Caspian basin - vectors of pathogens of anthropozoonoses

In the Volga-Caspian region there is abundant variety of parasitic species from different systematic groups. Some species ofparasites can be pathogenic not only for fish, but also for human that is why studies on the infection rate of commercial fish species by agents of are very topical for today. The work presents materials on invasiveness by the sanitary-significant helminthes of sheat fish, pike-perch, perch, pike, bream, Caspian roach, red-eye, sabrefish, silver bream, anchovy and ordinary kilka, herring, Caspian shad, black-backed shad. In parasite cenoses of all studied representatives of ichthyofauna there were from one to four species of helminthes which are pathogenic for human and warm-blooded animals. The obtained data indicate to the functioning and active circulation of natural foci of invasion ofAnisacidosis, Eustrongylidosis, apophallosis, rossicotremosis, corynosomosis, opisthorchiasis and pseudamphistomosis in the delta and avan-delta of the Volga River, which, in turn, points to the sanitary trouble of the Volga Caspian region.

SEASONAL CHANGES IN THE MICROSTRUCTURE OF EARLY STAGES OF OOGENESIS IN THE COMMON CARP (CYPRINUS CARPIO LINNAEUS, 1758) AND THE CASPIAN ROACH (RUTILUS RUTILUS CASPICUS JAKOWLEW, 1870) IN THE WEST COAST OF THE CASPIAN SEA

The work presents microstructural analysis of the oocytes of the common carp and the caspian roach that are on the stages of the protoplasmic and trophoplasmic (large) growth of the germ cells. Seasonal changes of quantitative and qualitative transformations of structural components of oocytes are also given. It is shown that from the early spring to the late autumn in the ovaries of the caspian roach and the common carp found are the oocytes of different generations, which are both at the generative and vegetative stages of growth of germ cells and along with this can occur, with varying intensity, resorption of whole oocytes and their individual structures. It has been established that spawning is common in the common carp, generative and regenerative processes occur simultaneously, while in the wobble spawning is simultaneous, the generative processes begin only after the regeneration of the sexual gland.