101
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Soldánová M, Selbach C, Kalbe M, Kostadinova A, Sures B. Swimmer's itch: etiology, impact, and risk factors in Europe. Trends Parasitol 2013; 29:65-74. [PMID: 23305618 DOI: 10.1016/j.pt.2012.12.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 12/03/2012] [Accepted: 12/04/2012] [Indexed: 10/27/2022]
Abstract
This review summarizes current knowledge about the occurrence and distribution of swimmer's itch, with a focus on Europe. Although recent publications have reviewed the biology and systematics of bird schistosomes and their complex host-parasite interactions, the underlying ecological factors that create favorable conditions for the parasites and the way humans interact with infested water bodies require further attention. Relevant studies from the past decade were analyzed to reveal an almost complete set of ecological factors as a prerequisite for establishing the life cycle of bird schistosomes. Based on both records of the occurrence of the parasite infective agents, and epidemiological studies that investigate outbreaks of swimmer's itch, this review concentrates on the risk factors for humans engaged in recreational water activities.
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Affiliation(s)
- Miroslava Soldánová
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 5, D-45141, Essen, Germany
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102
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Effect of suboptimal environment and host age on helminth community of black grouse (Tetrao tetrix). EUR J WILDLIFE RES 2012. [DOI: 10.1007/s10344-012-0681-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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103
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Molnár PK, Kutz SJ, Hoar BM, Dobson AP. Metabolic approaches to understanding climate change impacts on seasonal host-macroparasite dynamics. Ecol Lett 2012; 16:9-21. [DOI: 10.1111/ele.12022] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 07/23/2012] [Accepted: 09/24/2012] [Indexed: 11/27/2022]
Affiliation(s)
- Péter K. Molnár
- Department of Ecology and Evolutionary Biology; Princeton University; Eno Hall; Princeton; New Jersey; 08544; USA
| | - Susan J. Kutz
- Department of Ecosystem and Public Health; Faculty of Veterinary Medicine, University of Calgary; 3330 Hospital Dr. NW; Calgary; Alberta; T2N 4N1; Canada
| | - Bryanne M. Hoar
- Department of Ecosystem and Public Health; Faculty of Veterinary Medicine, University of Calgary; 3330 Hospital Dr. NW; Calgary; Alberta; T2N 4N1; Canada
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104
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Lunde KB, Resh VH, Johnson PTJ. Using an ecosystem-level manipulation to understand host-parasite interactions and how they vary with study venue. Ecosphere 2012. [DOI: 10.1890/es12-00001.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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105
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Studer A, Poulin R. Cercarial survival in an intertidal trematode: a multifactorial experiment with temperature, salinity and ultraviolet radiation. Parasitol Res 2012; 112:243-9. [DOI: 10.1007/s00436-012-3131-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/18/2012] [Indexed: 11/30/2022]
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106
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Blaustein AR, Gervasi SS, Johnson PTJ, Hoverman JT, Belden LK, Bradley PW, Xie GY. Ecophysiology meets conservation: understanding the role of disease in amphibian population declines. Philos Trans R Soc Lond B Biol Sci 2012; 367:1688-707. [PMID: 22566676 DOI: 10.1098/rstb.2012.0011] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Infectious diseases are intimately associated with the dynamics of biodiversity. However, the role that infectious disease plays within ecological communities is complex. The complex effects of infectious disease at the scale of communities and ecosystems are driven by the interaction between host and pathogen. Whether or not a given host-pathogen interaction results in progression from infection to disease is largely dependent on the physiological characteristics of the host within the context of the external environment. Here, we highlight the importance of understanding the outcome of infection and disease in the context of host ecophysiology using amphibians as a model system. Amphibians are ideal for such a discussion because many of their populations are experiencing declines and extinctions, with disease as an important factor implicated in many declines and extinctions. Exposure to pathogens and the host's responses to infection can be influenced by many factors related to physiology such as host life history, immunology, endocrinology, resource acquisition, behaviour and changing climates. In our review, we discuss the relationship between disease and biodiversity. We highlight the dynamics of three amphibian host-pathogen systems that induce different effects on hosts and life stages and illustrate the complexity of amphibian-host-parasite systems. We then review links between environmental stress, endocrine-immune interactions, disease and climate change.
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Affiliation(s)
- Andrew R Blaustein
- Department of Zoology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331-2914, USA.
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107
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Koprivnikar J, Marcogliese DJ, Rohr JR, Orlofske SA, Raffel TR, Johnson PTJ. Macroparasite infections of amphibians: what can they tell us? ECOHEALTH 2012; 9:342-360. [PMID: 22810498 DOI: 10.1007/s10393-012-0785-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 06/25/2012] [Accepted: 07/01/2012] [Indexed: 06/01/2023]
Abstract
Understanding linkages between environmental changes and disease emergence in human and wildlife populations represents one of the greatest challenges to ecologists and parasitologists. While there is considerable interest in drivers of amphibian microparasite infections and the resulting consequences, comparatively little research has addressed such questions for amphibian macroparasites. What work has been done in this area has largely focused on nematodes of the genus Rhabdias and on two genera of trematodes (Ribeiroia and Echinostoma). Here, we provide a synopsis of amphibian macroparasites, explore how macroparasites may affect amphibian hosts and populations, and evaluate the significance of these parasites in larger community and ecosystem contexts. In addition, we consider environmental influences on amphibian-macroparasite interactions by exploring contemporary ecological factors known or hypothesized to affect patterns of infection. While some macroparasites of amphibians have direct negative effects on individual hosts, no studies have explicitly examined whether such infections can affect amphibian populations. Moreover, due to their complex life cycles and varying degrees of host specificity, amphibian macroparasites have rich potential as bioindicators of environmental modifications, especially providing insights into changes in food webs. Because of their documented pathologies and value as bioindicators, we emphasize the need for broader investigation of this understudied group, noting that ecological drivers affecting these parasites may also influence disease patterns in other aquatic fauna.
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108
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Orlofske SA, Jadin RC, Preston DL, Johnson PTJ. Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians. Ecology 2012; 93:1247-53. [PMID: 22834364 DOI: 10.1890/11-1901.1] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. Here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (Ribeiroia ondatrae) infection in a focal amphibian host (Pseudacris regilla). In short-term predation bioassays involving mollusks, zooplankton, fish, larval insects, or newts, four of seven tested species removed 62-93% of infectious stages. In transmission experiments, damselfly nymphs (predators) and newt larvae (alternative hosts) reduced infection in P. regilla tadpoles by -50%, whereas mosquitofish (potential predators and alternative hosts) did not significantly influence transmission. Additional bioassays indicated that predators consumed parasites even in the presence of alternative prey. In natural wetlands, newts had similar infection intensities as P. regilla, suggesting that they commonly function as alternative hosts despite their unpalatability to downstream hosts, whereas mosquitofish had substantially lower infection intensities and are unlikely to function as hosts. These results underscore the importance of studying host-parasite interactions in complex communities and of broadly linking research on predation, biodiversity loss, and infectious diseases.
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Affiliation(s)
- Sarah A Orlofske
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309, USA.
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109
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Rossiter W, Sukhdeo MVK. Host Quality and Spatial Patterning in Infections of the Eastern Mudsnail (Ilyanassa obsoleta) by Two Trematodes (Himasthla quissetensis and Zoogonus rubellus). J Parasitol 2012; 98:245-55. [DOI: 10.1645/ge-2802.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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110
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Campião KM, Delatorre M, Rodrigues RB, da Silva RJ, Ferreira VL. The Effect of Local Environmental Variables on the Helminth Parasite Communities of the Pointedbelly Frog Leptodactylus podicipinus from Ponds in the Pantanal Wetlands. J Parasitol 2012; 98:229-35. [DOI: 10.1645/ge-2877.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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111
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Johnson PTJ, Preston DL, Hoverman JT, Henderson JS, Paull SH, Richgels KLD, Redmond MD. Species diversity reduces parasite infection through cross-generational effects on host abundance. Ecology 2012; 93:56-64. [DOI: 10.1890/11-0636.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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112
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Koehler AV, Springer YP, Randhawa HS, Leung TLF, Keeney DB, Poulin R. Genetic and phenotypic influences on clone-level success and host specialization in a generalist parasite. J Evol Biol 2011; 25:66-79. [PMID: 22022929 DOI: 10.1111/j.1420-9101.2011.02402.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studying resource specialization at the individual level can identify factors constraining the evolution of generalism. We quantified genotypic and phenotypic variability among infective stages of 20 clones of the parasitic trematode Maritrema novaezealandensis and measured their infection success and post-infection fitness (growth, egg output) in several crabs and amphipods. First, different clones varied in their infection success of different crustaceans. Second, neither genetic nor phenotypic traits had consistent effects on infection success across all host species. Although the results suggest a relationship between infection success and phenotypic variability, phenotypically variable clones were not better at infecting more host species than less variable ones. Third, genetic and phenotypic traits also showed no consistent correlations with post-infection fitness measures. Overall, we found no consistent clone-level specialization, with some clones acting as specialists and others, generalists. The trematode population therefore maintains an overall generalist strategy by comprising a mixture of clone-level specialists and generalists.
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Affiliation(s)
- Anson V Koehler
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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113
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The anthropogenic environment lessens the intensity and prevalence of gastrointestinal parasites in Balinese long-tailed macaques (Macaca fascicularis). Primates 2010; 52:117-28. [PMID: 21165669 DOI: 10.1007/s10329-010-0230-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
Abstract
The distribution of wildlife parasites in a landscape is intimately tied to the spatial distribution of hosts. In parasite species, including many gastrointestinal parasites, with obligate or common environmental life stages, the dynamics of the parasite can also be strongly affected by geophysical components of the environment. This is especially salient in host species, for example humans and macaques, which thrive across a wide variety of habitat types and quality and so are exposed to a wealth of environmentally resilient parasites. Here, we examine the effect of environmental and anthropogenic components of the landscape on the prevalence, intensity, and species diversity of gastrointestinal parasites across a metapopulation of long-tailed macaques on the island of Bali, Indonesia. Using principal-components analysis, we identified significant interaction effects between specific environmental and anthropogenic components of the landscape, parsing the Balinese landscape into anthropogenic (PC1), mixed environment (PC2), and non-anthropogenic (PC3) components. Further, we determined that the anthropogenic environment can mitigate the prevalence and intensity of specific gut parasites and the intensity of the overall community of gut parasites, but that non-anthropogenically driven landscape components have no significant effect in increasing or reducing the intensity or prevalence of the community of gut parasites in Balinese macaques.
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114
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The marine limpet Notoacmea scapha acts as a transmission sink for intertidal cercariae in Otago Harbour, New Zealand. J Helminthol 2010; 85:160-3. [PMID: 20678293 DOI: 10.1017/s0022149x10000404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Marine limpets, Notoacmea scapha, were collected from an intertidal mud flat in Otago Harbour, New Zealand, and examined for infection with larval trematodes. Three separate species of trematode (opecoelid sp. A, Acanthoparyphium sp. A and Curtuteria australis) were identified from the limpets, based on molecular evidence. This is the first report of these three trematodes in limpets, indicating that the latter are physiologically suitable second-intermediate hosts. However, based on ecological information on the diet of the parasites' definitive hosts, we conclude that the limpet N. scapha does not contribute to the transmission of any of the trematodes. Instead, it acts as a sink for cercariae that fail to locate appropriate second-intermediate hosts.
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115
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Merlo MJ, Parietti M, Etchegoin JA. Evaluation of species richness estimators in studies of diversity involving two larval digenean communities parasitizing snail hosts. Parasitol Res 2010; 107:1093-102. [DOI: 10.1007/s00436-010-1977-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 07/05/2010] [Indexed: 11/30/2022]
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116
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Genetic and environmental determinants of host use in the trematode Maritrema novaezealandensis (Microphallidae). Parasitology 2010; 138:100-6. [PMID: 20663252 DOI: 10.1017/s0031182010001022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Factors constraining host specificity are poorly understood. Intraspecific variation in host preferences in generalist parasites may reveal which factors affect patterns of host use, and thus the evolution of specialization. Here, laboratory experiments examined genetic variation in host preferences and the effect of a refugium against infection on host use. Firstly, 6 cercarial clones of the trematode Maritrema novaezealandensis (ranging widely in heterozygosities) were exposed simultaneously to 2 alternative hosts, the amphipods Heterophoxus stephenseni and Paracalliope novizealandiae, to assess host preferences and fitness correlations with parasite heterozygosity. All clones showed a distinct preference for H. stephenseni, though the extent of this preference varied among clones. No clear association was found between heterozygosity and either parasite infection success or preference for a particular host. Secondly, cercariae were exposed to the same 2 amphipods in both the presence and absence of sand (refugium for H. stephenseni). Without sand, infection levels were significantly higher in H. stephenseni than in P. novizealandiae. With sand, H. stephenseni was able to hide, offsetting the parasite's intrinsic preferences for this host. These results demonstrate the existence of genetic variation in host preferences, as well as the effect of environmental variables on observed patterns of host use.
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117
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Poulin R. Network analysis shining light on parasite ecology and diversity. Trends Parasitol 2010; 26:492-8. [PMID: 20561821 DOI: 10.1016/j.pt.2010.05.008] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 05/25/2010] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
The vast number of species making up natural communities, and the myriad interactions among them, pose great difficulties for the study of community structure, dynamics and stability. Borrowed from other fields, network analysis is making great inroads in community ecology and is only now being applied to host-parasite interactions. It allows a complex system to be examined in its entirety, as opposed to one or a few components at a time. This review explores what network analysis is and how it can be used to investigate parasite ecology. It also summarizes the first findings to emerge from network analyses of host-parasite interactions and identifies promising future directions made possible by this approach.
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Affiliation(s)
- Robert Poulin
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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118
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Johnson PTJ, Thieltges DW. Diversity, decoys and the dilution effect: how ecological communities affect disease risk. ACTA ACUST UNITED AC 2010; 213:961-70. [PMID: 20190121 DOI: 10.1242/jeb.037721] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Growing interest in ecology has recently focused on the hypothesis that community diversity can mediate infection levels and disease ('dilution effect'). In turn, biodiversity loss--a widespread consequence of environmental change--can indirectly promote increases in disease, including those of medical and veterinary importance. While this work has focused primarily on correlational studies involving vector-borne microparasite diseases (e.g. Lyme disease, West Nile virus), we argue that parasites with complex life cycles (e.g. helminths, protists, myxosporeans and many fungi) offer an excellent additional model in which to experimentally address mechanistic questions underlying the dilution effect. Here, we unite recent ecological research on the dilution effect in microparasites with decades of parasitological research on the decoy effect in macroparasites to explore key questions surrounding the relationship between community structure and disease. We find consistent evidence that community diversity significantly alters parasite transmission and pathology under laboratory as well as natural conditions. Empirical examples and simple transmission models highlight the diversity of mechanisms through which such changes occur, typically involving predators, parasite decoys, low competency hosts or other parasites. However, the degree of transmission reduction varies among diluting species, parasite stage, and across spatial scales, challenging efforts to make quantitative, taxon-specific predictions about disease. Taken together, this synthesis highlights the broad link between community structure and disease while underscoring the importance of mitigating ongoing changes in biological communities owing to species introductions and extirpations.
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Affiliation(s)
- P T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Ramaley N122, Campus Box 334, Boulder, CO 80309, USA.
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119
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Thieltges DW, Dolch T, Krakau M, Poulin R. Salinity gradient shapes distance decay of similarity among parasite communities in three marine fishes. JOURNAL OF FISH BIOLOGY 2010; 76:1806-1814. [PMID: 20557632 DOI: 10.1111/j.1095-8649.2010.02618.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Published data were used to compare the distance decay of similarity in parasite communities of three marine fish hosts: Atlantic cod Gadus morhua, the dab Limanda limanda and the flounder Platichthys flesus in two adjacent areas that differ with respect to the strength of a salinity gradient. In the Baltic Sea, which exhibits a strong salinity gradient from its connection with the North Sea in the west to its head in the north-east, parasite communities in all three fish hosts showed a significant decline of similarity with increasing distance. In contrast, among host populations in the North Sea, which is a fully marine environment, there was no such decline or only a weak relationship. The results suggest that environmental gradients like salinity can be strong driving forces behind patterns of distance decay in parasite communities of fishes.
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Affiliation(s)
- D W Thieltges
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand.
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120
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Spatial variation in parasite-induced mortality in an amphipod: shore height versus exposure history. Oecologia 2010; 163:651-9. [DOI: 10.1007/s00442-010-1593-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
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121
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Johnson PTJ, Dobson A, Lafferty KD, Marcogliese DJ, Memmott J, Orlofske SA, Poulin R, Thieltges DW. When parasites become prey: ecological and epidemiological significance of eating parasites. Trends Ecol Evol 2010; 25:362-71. [PMID: 20185202 DOI: 10.1016/j.tree.2010.01.005] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 01/07/2010] [Accepted: 01/18/2010] [Indexed: 10/19/2022]
Abstract
Recent efforts to include parasites in food webs have drawn attention to a previously ignored facet of foraging ecology: parasites commonly function as prey within ecosystems. Because of the high productivity of parasites, their unique nutritional composition and their pathogenicity in hosts, their consumption affects both food-web topology and disease risk in humans and wildlife. Here, we evaluate the ecological, evolutionary and epidemiological significance of feeding on parasites, including concomitant predation, grooming, predation on free-living stages and intraguild predation. Combining empirical data and theoretical models, we show that consumption of parasites is neither rare nor accidental, and that it can sharply affect parasite transmission and food web properties. Broader consideration of predation on parasites will enhance our understanding of disease control, food web structure and energy transfer, and the evolution of complex life cycles.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Ramaley N122, Campus Box 334, Boulder, CO 80309, USA.
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122
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Climate change and infectious disease: helminthological challenges to farmed ruminants in temperate regions. Animal 2010; 4:377-92. [DOI: 10.1017/s1751731109990991] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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123
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Shati AA. Factors Affecting the Prevalence of Human Schistosomiasis in Aseer Region, Saudi Arabia. ACTA ACUST UNITED AC 2009. [DOI: 10.3923/jbs.2009.815.819] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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124
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Abstract
AbstractSix species of digeneans (Proctoeces maculatus (Looss, 1901), Helicometra fasciata (Odhner, 1902), Helicometra pulchella (Odhner, 1902), Macvicaria alacris (Looss, 1901), Peracreadium genu (Nicoll, 1909) and Zoogonus rubellus (Olson, 1868)) were found for the first time in labrid fish (Symphodus tinca (Linnaeus, 1758), Labrus merula (Linnaeus, 1758) and Labrus viridis (Linnaeus, 1758)) from the Bay of Bizerte. Except for P. maculatus and Z. rubellus, which are limited to the rectum, these helminths colonize the entire digestive tract. The study of the seasonal prevalence, abundance and mean intensity shows that three parasites, P. maculatus, H. fasciata and P. genu are present throughout the year while H. pulchella, M. alacris and Z. rubellus are less frequent and appear only in spring (H. pulchella and M. alacris) or in spring and summer (Z. rubellus). The levels of infection and digenean faunal diversity in labrid fish from the Tunisian coasts are generally lower than those from localities within the western Mediterranean.
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125
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Fermer J, Culloty SC, Kelly TC, O’Riordan RM. Intrapopulational distribution of Meiogymnophallus minutus (Digenea, Gymnophallidae) infections in its first and second intermediate host. Parasitol Res 2009; 105:1231-8. [DOI: 10.1007/s00436-009-1545-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
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126
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Morgan ER, Wall R. Climate change and parasitic disease: farmer mitigation? Trends Parasitol 2009; 25:308-13. [PMID: 19540163 DOI: 10.1016/j.pt.2009.03.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 04/15/2009] [Accepted: 03/16/2009] [Indexed: 11/19/2022]
Abstract
Global climate change predictions suggest that far-ranging effects might occur in the population dynamics and distributions of livestock parasites, provoking fears of widespread increases in disease incidence and production loss. However, several biological mechanisms (including increased parasite mortality and more rapid acquisition of immunity), in tandem with changes in husbandry practices (including reproduction, housing, nutrition, breed selection, grazing patterns and other management interventions), might act to mitigate increased parasite development rates, preventing dramatic rises in overall levels of disease. Such changes might, therefore, counteract predicted climate-driven increases in parasite challenge. Optimum mitigation strategies will be highly system specific and depend on detailed understanding of interactions between climate, parasite abundance, host availability and the cues for and economics of farmer intervention.
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Affiliation(s)
- Eric R Morgan
- Veterinary Parasitology & Ecology Group, School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.
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127
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Parasite zoonoses and climate change: molecular tools for tracking shifting boundaries. Trends Parasitol 2009; 25:285-91. [PMID: 19428303 DOI: 10.1016/j.pt.2009.03.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 02/19/2009] [Accepted: 03/05/2009] [Indexed: 11/21/2022]
Abstract
For human, domestic animal and wildlife health, key effects of directional climate change include the risk of the altered occurrence of infectious diseases. Many parasite zoonoses have high potential for vulnerability to the new climate, in part because their free-living life-cycle stages and ectothermic hosts are directly exposed to climatic conditions. For these zoonoses, climate change can shift boundaries for ecosystem components and processes integral to parasite transmission and persistence, and these shifts can impact host health. Vulnerable boundaries include those for spatial distributions, host-parasite assemblages, demographic rates, life-cycle phenologies, associations within ecosystems, virulence, and patterns of infection and disease. This review describes these boundary shifts and how molecular techniques can be applied to defining the new boundaries.
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128
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Johnson PTJ, Lund PJ, Hartson RB, Yoshino TP. Community diversity reduces Schistosoma mansoni transmission, host pathology and human infection risk. Proc Biol Sci 2009; 276:1657-63. [PMID: 19203926 DOI: 10.1098/rspb.2008.1718] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Global biodiversity loss and disease emergence are two of the most challenging issues confronting science and society. Recently, observed linkages between species-loss and vector-borne infections suggest that biodiversity may help reduce pathogenic infections in humans and wildlife, but the mechanisms underlying this relationship and its applicability to a broader range of pathogens have remained speculative. Here, we experimentally evaluated the effects of host community structure on transmission of the human pathogen, Schistosoma mansoni, which alternates between snail intermediate hosts and vertebrate definitive hosts. By manipulating parasite exposure and community diversity, we show that heterospecific communities cause a 25-50 per cent reduction in infection among snail hosts (Biomphalaria glabrata). Infected snails raised alongside non-host snails (Lymnaea or Helisoma sp.) also produced 60-80 per cent fewer cercariae, suggesting that diverse communities could reduce human infection risk. Because focal host density was held constant during experiments, decreases in transmission resulted entirely from diversity-mediated pathways. Finally, the decrease in infection in mixed-species communities led to an increase in reproductive output by hosts, representing a novel example of parasite-mediated facilitation. Our results underscore the significance of community structure on transmission of complex life-cycle pathogens, and we emphasize enhanced integration between ecological and parasitological research on the diversity-disease relationship.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
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Cryptic species complexes in manipulative echinostomatid trematodes: when two become six. Parasitology 2008; 136:241-52. [PMID: 19091157 DOI: 10.1017/s0031182008005374] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARY Recent studies have shown that some digenean trematodes previously identified as single species due to the lack of distinguishing morphological characteristics actually consist of a number of genetically distinct cryptic species. We obtained mitochondrial 16S and nuclear ITS1 sequences for the redial stages of Acanthoparyphium sp. and Curtuteria australis collected from snails and whelks at various locations around Otago Peninsula, New Zealand. These two echinostomes are well-known host manipulators whose impact extends to the entire intertidal community. Using phylogenetic analyses, we found that Acanthoparyphium sp. is actually composed of at least 4 genetically distinct species, and that a cryptic species of Curtuteria occurs in addition to C. australis. Molecular data obtained for metacercariae dissected from cockle second intermediate hosts matched sequences obtained for Acanthoparyphium sp. A and C. australis rediae, respectively, but no other species. The various cryptic species of both Acanthoparyphium and Curtuteria also showed an extremely localized pattern of distribution: some species were either absent or very rare in Otago Harbour, but reached far higher prevalence in nearby sheltered inlets. This small-scale spatial segregation is unexpected as shorebird definitive hosts can disperse trematode eggs across wide geographical areas, which should result in a homogeneous mixing of the species on small geographical scales. Possible explanations for this spatial segregation of the species include sampling artefacts, local adaptation by first intermediate hosts, environmental conditions, and site fidelity of the definitive hosts.
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130
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Helminth species diversity of mammals: parasite species richness is a host species attribute. Parasitology 2008; 135:1701-5. [DOI: 10.1017/s0031182008005040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
SUMMARYStudies investigating parasite diversity have shown substantial geographical variation in parasite species richness. Most of these studies have, however, adopted a local scale approach, which may have masked more general patterns. Recent studies have shown that ectoparasite species richness in mammals seems highly repeatable among populations of the same mammal host species at a regional scale. In light of these new studies we have reinvestigated the case of parasitic helminths by using a large data set of parasites from mammal populations in 3 continents. We collected homogeneous data and demonstrated that helminth species richness is highly repeatable in mammals at a regional scale. Our results highlight the strong influence of host identity in parasite species richness and call for future research linking helminth species found in a given host to its ecology, immune defences and potential energetic trade-offs.
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131
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Leung TLF, Poulin R. Size-dependent pattern of metacercariae accumulation in Macomona liliana: the threshold for infection in a dead-end host. Parasitol Res 2008; 104:177-80. [DOI: 10.1007/s00436-008-1166-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 08/13/2008] [Indexed: 10/21/2022]
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Johnson PTJ, Hartson RB, Larson DJ, Sutherland DR. Diversity and disease: community structure drives parasite transmission and host fitness. Ecol Lett 2008; 11:1017-26. [PMID: 18616550 DOI: 10.1111/j.1461-0248.2008.01212.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Changes in host diversity and community structure have been linked to disease, but the mechanisms underlying such relationships and their applicability to non-vector-borne disease systems remain conjectural. Here we experimentally investigated how changes in host community structure affected the transmission and pathology of the multi-host parasite Ribeiroia ondatrae, which is a widespread cause of amphibian limb deformities. We exposed larval amphibians to parasites in monospecific or heterospecific communities, and varied host number to differentiate between density- and diversity-mediated effects on transmission. In monospecific communities, exposure to Ribeiroia significantly increased mortality (15%), malformations (40%) and time-to-metamorphosis in toads. However, the presence of tree frogs significantly reduced infection in toads, leading to fewer malformations and higher survival than observed in monospecific communities, providing evidence of parasite-mediated facilitation. Our results suggest that interspecific variation in parasite resistance can inhibit parasite transmission in multi-species communities, reducing infection and pathology in sensitive hosts.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Ramaley N122, Campus Box 334, Boulder, CO 80309, USA.
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Lafferty KD, Allesina S, Arim M, Briggs CJ, De Leo G, Dobson AP, Dunne JA, Johnson PTJ, Kuris AM, Marcogliese DJ, Martinez ND, Memmott J, Marquet PA, McLaughlin JP, Mordecai EA, Pascual M, Poulin R, Thieltges DW. Parasites in food webs: the ultimate missing links. Ecol Lett 2008; 11:533-46. [PMID: 18462196 PMCID: PMC2408649 DOI: 10.1111/j.1461-0248.2008.01174.x] [Citation(s) in RCA: 494] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 02/09/2008] [Accepted: 02/22/2008] [Indexed: 11/26/2022]
Abstract
Parasitism is the most common consumer strategy among organisms, yet only recently has there been a call for the inclusion of infectious disease agents in food webs. The value of this effort hinges on whether parasites affect food-web properties. Increasing evidence suggests that parasites have the potential to uniquely alter food-web topology in terms of chain length, connectance and robustness. In addition, parasites might affect food-web stability, interaction strength and energy flow. Food-web structure also affects infectious disease dynamics because parasites depend on the ecological networks in which they live. Empirically, incorporating parasites into food webs is straightforward. We may start with existing food webs and add parasites as nodes, or we may try to build food webs around systems for which we already have a good understanding of infectious processes. In the future, perhaps researchers will add parasites while they construct food webs. Less clear is how food-web theory can accommodate parasites. This is a deep and central problem in theoretical biology and applied mathematics. For instance, is representing parasites with complex life cycles as a single node equivalent to representing other species with ontogenetic niche shifts as a single node? Can parasitism fit into fundamental frameworks such as the niche model? Can we integrate infectious disease models into the emerging field of dynamic food-web modelling? Future progress will benefit from interdisciplinary collaborations between ecologists and infectious disease biologists.
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Affiliation(s)
- Kevin D Lafferty
- Western Ecological Research Center, U.S. Geological Survey. c/o Marine Science Institute, UC, Santa Barbara, CA 93106, USA.
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