The Biology and Evolution of Trematodes
01 Jan 2003-
About: The article was published on 2003-01-01. It has received 247 citations till now.
Citations
More filters
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.
389 citations
Cites background from "The Biology and Evolution of Tremat..."
...In particular, constraints on cercarial output are not the same across all species (Galaktionov and Dobrovolskij, 2003)....
[...]
...There exist constraints on maximal cercarial output that vary among trematode species and families (Galaktionov and Dobrovolskij, 2003), and these undoubtedly determine to a great extent how cercarial output responds to temperature....
[...]
...In some species, although cercarial production is inhibited below a certain temperature, the production of rediae or sporocysts continues and these generative stages accumulate inside the snail (Galaktionov and Dobrovolskij, 2003)....
[...]
...among trematode species and families (Galaktionov and Dobrovolskij, 2003), and these undoubtedly...
[...]
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.
327 citations
Cites background from "The Biology and Evolution of Tremat..."
...…produces a finite number of cercariae per snail (total output genetically predermined by its number of totipotent cells), whereas in other species it gives rise to a virtually infinite succession of cercariae marked by energy availability (Erasmus, 1972; Galaktionov and Dovrovolskij, 2003)....
[...]
...Cercarial output by snails is a key component of the trematode’s transmission success (Erasmus, 1972; Galaktionov and Dovrovolskij, 2003)....
[...]
...Constraints on maximal cercarial output vary among trematode species and families (Galaktionov and Dovrovolskij, 2003), determining how cercarial output responds to temperature....
[...]
...In some digeneans, although cercarial production is inhibited below a certain temperature, the production of rediae or sporocysts continues and the generative stages accumulate inside the snail (Galaktionov and Dovrovolskij, 2003)....
[...]
TL;DR: edited by D.H. Clayton and J. Moore, Oxford University Press, 1997.
Abstract: edited by D.H. Clayton and J. Moore, Oxford University Press, 1997. pound60.00 (hbk)/ pound25.00 (pbk) (xi+473 pages) ISBN 0 19 854893 1/0 19 854892/3.
231 citations
TL;DR: It is concluded that helminth diseases should be listed among the infectious diseases with which special care should be taken because of climate change in the future, especially in temperate and colder northern latitudes and in areas of high altitude.
Abstract: Current knowledge of animal and zoonotic helminthiases in which effects of climate change have been detected is reviewed. Climate variables are able to affect the prevalence, intensity and geographical distribution of helminths, directly influencing free-living larval stages and indirectly influencing mainly invertebrate, but also vertebrate, hosts. The impact of climate change appears to be more pronounced in trematodes, and is mainly shown by increased cercarial production and emergence associated with global warming. Fascioliasis, schistosomiasis (S. japonicum) and cercarial dermatitis caused by avian schistosomes have been the focus of study. Alveolar echinococcosis is currently the only cestode disease that climate change has been found to influence. Nematodiases, including heterakiasis, different trichostrongyliases and protostrongyliases, ancylostomiases and dirofilariases, are the helminth diseases most intensively analysed with regard to climate change. It may be concluded that helminth diseases should be listed among the infectious diseases with which special care should be taken because of climate change in the future, especially in temperate and colder northern latitudes and in areas of high altitude.
151 citations
Cites background from "The Biology and Evolution of Tremat..."
...In three-host life cycles, the vertebrate host becomes infected by ingesting the second intermediate host, usually an invertebrate (molluscs, insects, crustaceans) or an exothermic vertebrate (fish, frogs, reptiles) (23, 30)....
[...]
TL;DR: It is demonstrated that this proliferative larval cell population (germinal cells) shares some molecular signatures with stem cells from diverse organisms, in particular neoblasts of planarians (free-living relatives of schistosomes), and suggests that an ancient stem cell-based developmental program may have enabled the evolution of the complex life cycle of parasitic flatworms.
Abstract: Schistosomes infect hundreds of millions of people in the developing world. Transmission of these parasites relies on a stem cell-driven, clonal expansion of larvae inside a molluscan intermediate host. How this novel asexual reproductive strategy relates to current models of stem cell maintenance and germline specification is unclear. Here, we demonstrate that this proliferative larval cell population (germinal cells) shares some molecular signatures with stem cells from diverse organisms, in particular neoblasts of planarians (free-living relatives of schistosomes). We identify two distinct germinal cell lineages that differ in their proliferation kinetics and expression of a nanos ortholog. We show that a vasa/PL10 homolog is required for proliferation and maintenance of both populations, whereas argonaute2 and a fibroblast growth factor receptor-encoding gene are required only for nanos-negative cells. Our results suggest that an ancient stem cell-based developmental program may have enabled the evolution of the complex life cycle of parasitic flatworms.
DOI: http://dx.doi.org/10.7554/eLife.00768.001
123 citations
References
More filters
TL;DR: In this paper, an ad hoc committee was established to establish working definitions of a few terms used and misused by parasitological ecologists as a guide for authors submitting papers to The Journal of Parasitology.
Abstract: In February 1981, ASP President Elmer Noble on recommendation from the Editor, Austin Maclnnis, appointed an ad hoc committee \"to establish working definitions of a few terms used and misused by parasitological ecologists\" as a guide for authors submitting papers to The Journal of Parasitology. Appointed to the committee were Drs. Gerald Esch, John Holmes, Armand Kuris, Gerhard Schad, and Leo Margolis (Chairman). As a starting point the committee examined the recommendations (Margolis et al., 1982) prepared by a similar committee established by the Parasitology Section of the Canadian Society of Zoologists. The Canadian Committee concerned itself only with terms required to express concepts related to the number of hosts in a sample infected with a particular species of parasite, and to the number of individuals of a particular parasite in each host in a sample. As noted below the present committee also dealt with several other ecological terms that are not now being used in a consistent manner in parasitological literature. The following are the committee's recommendations, annotated as required:
1,923 citations
[...]
TL;DR: Understanding Homosexuality : Its Biological and Psychological Bases by J. A. Loraine.
Abstract: Understanding Homosexuality : Its Biological and Psychological Bases. By J. A. Loraine. Pp. 217. (Medical and Technical Publishing: Lancaster, October 1974.) £6.50.
1,706 citations
Book•
30 Sep 1997TL;DR: That lexity is an inherent and avoidable outcome of natural systems is a major theme of this book and I have little doubt that it will help improve countless diverse, human agendas.
Abstract: parallels to selection for group behavior in natural populations. It could be argued that all scientific inquiry is based on the assertion that gathering information increases our understanding of the natural world, and that we should use this information to further improve countless diverse, human agendas. A great amount of information is gathered and disseminated in this second volume of t e Desig and Nature series-and it amounts to a sometimes overwhelming and always stimulating array of biological and engineering questions. The high cost of the book will limit its audience to academic and corporate buyers, but it is this same group who has the most to gain from integrating scientific disciplines to a level beyond simple metaphor. That com lexity is an inherent and u avoidable outcome of natural systems is a major theme of this book and I have little doubt that such
1,319 citations
"The Biology and Evolution of Tremat..." refers background in this paper
...Parasitic castration of molluscan hosts is a frequent result of the development of trematode parthenitae (see reviews: Ginetsinskaya, 1968; Wright, 1966b; Thompson, 1990, 1997; Thompson and Kavaliers, 1994; Poulin, 1998; Gorbushin, 2000)....
[...]
TL;DR: P parasite coevolution is superior to previous models of the evolution of sex by supporting the stability of sex under the following challenging conditions: very low fecundity, realistic patterns of genotype fitness and changing environment, and frequent mutation to parthenogenesis, even while sex pays the full 2-fold cost.
Abstract: Darwinian theory has yet to explain adequately the fact of sex. If males provide little or no aid to offspring, a high (up to 2-fold) extra average fitness has to emerge as a property of a sexual parentage if sex is to be stable. The advantage must presumably come from recombination but has been hard to identify. It may well lie in the necessity to recombine defenses to defeat numerous parasites. A model demonstrating this works best for contesting hosts whose defense polymorphisms are constrained to low mutation rates. A review of the literature shows that the predictions of parasite coevolution fit well with the known ecology of sex. Moreover, parasite coevolution is superior to previous models of the evolution of sex by supporting the stability of sex under the following challenging conditions: very low fecundity, realistic patterns of genotype fitness and changing environment, and frequent mutation to parthenogenesis, even while sex pays the full 2-fold cost.
1,236 citations
918 citations
"The Biology and Evolution of Tremat..." refers background in this paper
...Treatises of K.I. Skrjabin (1947-1975) and S. Yamaguti (1958, 1971) contain an enormous amount of material, but they are outdated in many respects....
[...]