Kirill V. Galaktionov
Other affiliations: Saint Petersburg State University
Bio: Kirill V. Galaktionov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Intermediate host & Population. The author has an hindex of 15, co-authored 55 publications receiving 918 citations. Previous affiliations of Kirill V. Galaktionov include Saint Petersburg State University.
Papers published on a yearly basis
01 Jan 2003
25 Dec 2010
TL;DR: This work focuses on the organization of parthenogenetic and hermaphroditic generations of trematodes and their larvae, as well as specific traits of populations formed by trematode populations.
Abstract: Preface. Introduction. Acknowledgements. 1: Organization of parthenogenetic and hermaphroditic generations of trematodes. 1. Parthenogenetic generations and their larvae. 2. The hermaphroditic generation. 2: The trematode life cycle as a system of adaptations. 1. Adaptations of the first parthenogenetic generation. 2. Adaptations of daughter generations of parthenitae. 3. Hermaphroditic generation. 3: The main types of trematode life cycles. 1. Trixenous (three-host) life cycles. 2. Trixenous (three-host) life cycles with two endogenous ag-glomerations. 3. Dixenous (two-host) life cycles. 4. Homoxenous (one-host) life cycles. 5. Tetraxenous (four-host) life cycles. 4: Specific traits of populations formed by trematodes. 1. On the nature of trematode populations. 2. Host-parasite interactions and their manifestation on popula-tional level. 3. Phase analysis of trematode populations. 4. General notes. 5: The main trends in trematode evolution. 1. The main trends of morphological evolution of trematodes. 2. Ways of biological radiation of trematodes into different ecosystems. 6: Evolution of life cycles and phylogeny of trematodes. 1. Origin and evolution of trematode life cycles. 2. The main trends in evolution of trematode life cycles. 3. Possible approaches to establishing a natural classification of trematodes. References. Index.
TL;DR: Results demonstrate that speciation within the MPG was not associated with co-speciation with either the first intermediate or final hosts, but rather by host-switching events coincident with glacial cycles in the Northern Hemisphere during the late Pliocene/Pleistocene.
Abstract: The ‘pygmaeus’ microphallids (MPG) are a closely related group of 6 digenean (Platyhelminthes: Trematoda) Microphallus species that share a derived 2-host life cycle in which metacercariae develop inside daughter sporocysts in the intermediate host (intertidal and subtidal gastropods, mostly of the genus Littorina) and are infective to marine birds (ducks, gulls and waders). Here we investigate MPG transmission patterns in coastal ecosystems and their diversification with respect to historical events, host switching and host-parasite co-evolution. Species phylogenies and phylogeographical reconstructions are estimated on the basis of 28S, ITS1 and ITS2 rDNA data and we use a combination of analyses to test the robustness and stability of the results, and the likelihood of alternative biogeographical scenarios. Results demonstrate that speciation within the MPG was not associated with co-speciation with either the first intermediate or final hosts, but rather by host-switching events coincident with glacial cycles in the Northern Hemisphere during the late Pliocene/Pleistocene. These resulted in the expansion of Pacific biota into the Arctic-North Atlantic and periodic isolation of Atlantic and Pacific populations. Thus we hypothesize that contemporary species of MPG and their host associations resulted from fragmentation of populations in regional refugia during stadials, and their subsequent range expansion from refugial centres during interstadials.
TL;DR: The prevalence of the parasites in two species of intermediate host (Littorinasaxatilis and Littorina obtusata) on seashores near fishing industry complexes, fish farms and at control sites indicates that the vulnerability to trematode infection differs between the two snail species depending on the variation in the distribution patterns in the intertidal zone.
Abstract: In this study we examined how the variation in the distribution of six species of seabird trematodes was influenced by human activities along the subarctic Barents Sea coast of northern Norway. This was done by comparing the prevalence of the parasites in two species of intermediate host (Littorinasaxatilis and Littorina obtusata) on seashores near fishing industry complexes, fish farms and at control sites. In L. saxatilis there were higher prevalences at sites influenced by human activities for three out of five trematode species (Microphallus piriformes, M. similis, Cryptocotyle lingua) which have gulls (Larus spp.) as their predominant final hosts, while in L. obtusata, only M. similis was more common at sites with human activity. For M. pygmaeus, a trematode which has the common eider (Somateria mollissima) as its most predominant final host, the prevalence in L.␣saxatilis tended to be higher at sites with fishing industry, but differences were not significant. No such tendency was found in L. obtusata for this trematode. The overall prevalence in L. obtusata was lower than in L.␣saxatilis. This indicates that the vulnerability to trematode infection differs between the two snail species depending on the variation in the distribution patterns in the intertidal zone. Gulls tend to concentrate in areas near fishing industry and fish farms to feed on fish offal, which leads to an increase in the transmission between hosts, and to a higher level of parasite infection, locally.
TL;DR: The causes of changing species composition between regions are probably the harsh climate in the eastern part of the study area reducing the probability of successful transmission of digeneans with complicated life cycles, and the distribution of different final hosts.
Abstract: An important component of the parasite fauna of seabirds in arctic regions are the flukes (Digena). Different species of digeneans have life cycles which may consist of 1 intermediate host and no free-living larval stages, 2 intermediate hosts and 1 free-living stage, or 2 intermediate hosts and 2 free-living larval stages. This study examined the distribution of such parasites in the intertidal zones of the southern coast of the Barents Sea (northwestern Russia and northern Norway) by investigating 2 species of periwinkles (Littorina saxatilis and L. obtusata) which are intermediate hosts of many species of digeneans. A total of 26,020 snails from 134 sampling stations were collected. The study area was divided into 5 regions, and the number of species, frequency of occurrence and prevalence of different digenean species and groups of species (depending on life cycle complexity) were compared among these regions, statistically controlling for environmental exposure. We found 14 species of digeneans, of which 13 have marine birds as final hosts. The number of species per sampling station increased westwards, and was higher on the Norwegian coast than on the Russian coast. The frequency of occurrence of digeneans with more than 1 intermediate host increased westwards, making up a larger proportion of the digeneans among infected snails. This was significant in L. saxatilis. The prevalence of different species showed the same pattern, and significantly more snails of both species were infected with digeneans with complicated life cycles in the western regions. In L. saxatilis, environmental exposure had a statistically significant effect on the distribution of the most common digenean species. This was less obvious in L. obtusata. The causes of changing species composition between regions are probably (1) the harsh climate in the eastern part of the study area reducing the probability of successful transmission of digeneans with complicated life cycles, and (2) the distribution of different final hosts.
01 Jan 1976
TL;DR: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in Solubility with rise in temperature.
Abstract: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.
TL;DR: The results suggest that the small increases in air and water temperature forecast by many climate models will not only influence the geographical distribution of some diseases, but may also promote the proliferation of their infective stages in many ecosystems.
Abstract: Global warming can affect the world's biota and the functioning of ecosystems in many indirect ways. Recent evidence indicates that climate change can alter the geographical distribution of parasitic diseases, with potentially drastic consequences for their hosts. It is also possible that warmer conditions could promote the transmission of parasites and raise their local abundance. Here I have compiled experimental data on the effect of temperature on the emergence of infective stages (cercariae) of trematode parasites from their snail intermediate hosts. Temperature-mediated changes in cercarial output varied widely among trematode species, from small reductions to 200-fold increases in response to a 10 degrees C rise in temperature, with a geometric mean suggesting an almost 8-fold increase. Overall, the observed temperature-mediated increases in cercarial output are much more substantial than those expected from basic physiological processes, for which 2- to 3-fold increases are normally seen. Some of the most extreme increases in cercarial output may be artefacts of the methods used in the original studies; however, exclusion of these extreme values has little impact on the preceding conclusion. Across both species values and phylogenetically independent contrasts, neither the magnitude of the initial cercarial output nor the shell size of the snail host correlated with the relative increase in cercarial production mediated by rising temperature. In contrast, the latitude from which the snail-trematode association originated correlated negatively with temperature-mediated increases in cercarial production: within the 20 degrees to 55 degrees latitude range, trematodes from lower latitudes showed more pronounced temperature-driven increases in cercarial output than those from higher latitudes. These results suggest that the small increases in air and water temperature forecast by many climate models will not only influence the geographical distribution of some diseases, but may also promote the proliferation of their infective stages in many ecosystems.
TL;DR: In two different studies, time-lapse videography was used to quantify birds at fine spatial scales, and then related bird communities to larval trematode communities in snail populations sampled at the same small spatial scales to study species richness, species heterogeneity and abundance of trematodes in host snails.
Abstract: An unappreciated facet of biodiversity is that rich communities and high abundance may foster parasitism. For parasites that sequentially use different host species throughout complex life cycles, parasite diversity and abundance in 'downstream' hosts should logically increase with the diversity and abundance of 'upstream' hosts (which carry the preceding stages of parasites). Surprisingly, this logical assumption has little empirical support, especially regarding metazoan parasites. Few studies have attempted direct tests of this idea and most have lacked the appropriate scale of investigation. In two different studies, we used time-lapse videography to quantify birds at fine spatial scales, and then related bird communities to larval trematode communities in snail populations sampled at the same small spatial scales. Species richness, species heterogeneity and abundance of final host birds were positively correlated with species richness, species heterogeneity and abundance of trematodes in host snails. Such community-level interactions have rarely been demonstrated and have implications for community theory, epidemiological theory and ecosystem management.
TL;DR: Indirect evidence exists that warming increased disease in turtles, and protection, pollution, and terrestrial pathogens increased mammal disease, and release from overfished predators increased sea urchin disease.
Abstract: ▪ Abstract Many factors (climate warming, pollution, harvesting, introduced species) can contribute to disease outbreaks in marine life Concomitant increases in each of these makes it difficult to attribute recent changes in disease occurrence or severity to any one factor For example, the increase in disease of Caribbean coral is postulated to be a result of climate change and introduction of terrestrial pathogens Indirect evidence exists that (a) warming increased disease in turtles; (b) protection, pollution, and terrestrial pathogens increased mammal disease; (c) aquaculture increased disease in mollusks; and (d) release from overfished predators increased sea urchin disease In contrast, fishing and pollution may have reduced disease in fishes In other taxa (eg, sea grasses, crustaceans, sharks), there is little evidence that disease has changed over time The diversity of patterns suggests there are many ways that environmental change can interact with disease in the ocean
TL;DR: The present review shows that trematodes, similarly as other helminths presenting larval stages living freely in the environment and/or larval Stage parasitic in invertebrates easily affected by climate change as arthropods and molluscs as intermediate hosts, may be largely more susceptible to climate change impact than those helminthiases in whose life cycle such phases are absent or reduced to a minimum.
Abstract: The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general (viruses, bacteriae, protozoans). The aim of the present paper is to review the impact of climate change on helminthiases transmitted by snails, invertebrates which are pronouncedly affected by meteorological factors, by focusing on trematodiases. First, the knowledge on the effects of climate change on trematodiases in general is reviewed, including aspects such as influence of temperature on cercarial output, cercarial production variability in trematode species, influences of magnitude of cercarial production and snail host size, cercarial quality, duration of cercarial production increase and host mortality, influence of latitude, and global-warming-induced impact of trematodes. Secondly, important zoonotic diseases such as fascioliasis, schistosomiasis and cercarial dermatitis are analysed from the point of view of their relationships with meteorological factors. Emphasis is given to data which indicate that climate change influences the characteristics of these trematodiases in concrete areas where these diseases are emerging in recent years. The present review shows that trematodes, similarly as other helminths presenting larval stages living freely in the environment and/or larval stages parasitic in invertebrates easily affected by climate change as arthropods and molluscs as intermediate hosts, may be largely more susceptible to climate change impact than those helminths in whose life cycle such phases are absent or reduced to a minimum. Although helminths also appear to be affected by climate change, their main difference with microparasites lies on the usually longer life cycles of helminths, with longer generation times, slower population growth rates and longer time period needed for the response in the definitive host to become evident. Consequently, after a pronounced climate change in a local area, modifications in helminth populations need more time to be obvious or detectable than modifications in microparasite populations. Similarly, the relation of changes in a helminthiasis with climatic factor changes, as extreme events elapsed relatively long time ago, may be overlooked if not concretely searched for. All indicates that this phenomenon has been the reason for previous analyses to conclude that helminthiases do not constitute priority targets in climate change impact studies.