Evolution of complex life cycles in helminth parasites

Nature ◽  
2003 ◽  
Vol 425 (6957) ◽  
pp. 480-484 ◽  
Author(s):  
Geoff A. Parker ◽  
Jimmy C. Chubb ◽  
Michael A. Ball ◽  
Guy N. Roberts
Keyword(s):  
Life Cycles ◽  
Helminth Parasites ◽  
Complex Life Cycles

Influence of the transmission of parasites from prey fishes on the composition of the parasite community of a predatory fish

1995 ◽  
Vol 52 (S1) ◽  
pp. 233-245 ◽  
Author(s):  
E. Tellervo Valtonen ◽  
Markku Julkunen
Keyword(s):  
Parasite Community ◽  
Life Cycles ◽  
Predatory Fish ◽  
Helminth Parasites ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Lota Lota ◽  
Gymnocephalus Cernuus ◽  
Adult Trematode ◽  
Bothnian Bay

Helminth parasites and diet of seven freshwater fishes (Lota lota and six common prey species) from the Bothnian Bay, Baltic Sea, were studied monthly or bimonthly during 1978. Twenty-one of the 32 parasites with complex life cycles were shared between Lota lota and its prey fishes and are thus transmissible from prey to predator. Gymnocephalus cernuus and L. lota had the greatest number of shared species (13). Larval and adult cestodes, nematodes, and acanthocephalans could re-establish in the predator, but only one adult trematode was capable of this transition. Infracommunity species diversity was highest in L. lota (eH′ = 3.54), which also had the most species (24), the highest mean number of species and individuals of a given species per fish (6.3 and 62, respectively), and the greatest number of worms in one fish (520). Variety of diet was key in determining exposure to parasite species. However, most specificity finally determined if a given parasite could establish and mature. No ecologically explicable suites of parasites were found in any fish species, except in a few cases where parasites used related intermediate hosts. However, the composition of these suites was not retained in the predator. Unlike in L. lota, important parasites of prey fishes were typically specialists.

scholarly journals Promising Technologies in the Field of Helminth Vaccines

2021 ◽  
Vol 12 ◽  
Author(s):  
Dilhan J. Perera ◽  
Momar Ndao
Keyword(s):  
Viral Vectors ◽  
Life Cycles ◽  
Helminth Parasites ◽  
Chronic Infections ◽  
Complex Life Cycles ◽  
Wide Range ◽  
Human Infections ◽  
Conventional Vaccine ◽  
Induced Immunity ◽  
Antigenic Mimicry

Helminths contribute a larger global burden of disease than both malaria and tuberculosis. These eukaryotes have caused human infections since before our earliest recorded history (i.e.: earlier than 1200 B.C. for Schistosoma spp.). Despite the prevalence and importance of these infections, helminths are considered a neglected tropical disease for which there are no vaccines approved for human use. Similar to other parasites, helminths are complex organisms which employ a plethora of features such as: complex life cycles, chronic infections, and antigenic mimicry to name a few, making them difficult to target by conventional vaccine strategies. With novel vaccine strategies such as viral vectors and genetic elements, numerous constructs are being defined for a wide range of helminth parasites; however, it has yet to be discussed which of these approaches may be the most effective. With human trials being conducted, and a pipeline of potential anti-helminthic antigens, greater understanding of helminth vaccine-induced immunity is necessary for the development of potent vaccine platforms and their optimal design. This review outlines the conventional and the most promising approaches in clinical and preclinical helminth vaccinology.

scholarly journals Impacts of climate change on the complex life cycles of fish

2012 ◽  
Vol 22 (2) ◽  
pp. 121-139 ◽  
Author(s):  
Pierre Petitgas ◽  
Adriaan D. Rijnsdorp ◽  
Mark Dickey-Collas ◽  
Georg H. Engelhard ◽  
Myron A. Peck ◽  
...  
Keyword(s):  
Climate Change ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Impacts Of Climate Change

Complex Life Cycles: Why Refrain from Growth before Reproduction in the Adult Niche?

2013 ◽  
Vol 181 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Daniel P. Benesh ◽  
James C. Chubb ◽  
Geoff A. Parker
Keyword(s):  
Life Cycles ◽  
Complex Life Cycles

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

Abiotic versus biotic hierarchies in the assembly of parasite populations

Parasitology ◽  
2009 ◽  
Vol 137 (4) ◽  
pp. 743-754 ◽  
Author(s):  
T. K. ANDERSON ◽  
M. V. K. SUKHDEO
Keyword(s):  
Fundulus Heteroclitus ◽  
Classification Tree ◽  
Benthic Invertebrate ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Parasite Communities ◽  
Parametric Classification ◽  
The Common ◽  
Correct Category ◽  
Parasite Populations

SUMMARYThe presence or absence of parasites within host populations is the result of a complex of factors, both biotic and abiotic. This study uses a non-parametric classification tree approach to evaluate the relative importance of key abiotic and biotic drivers controlling the presence/absence of parasites with complex life cycles in a sentinel, the common killifish Fundulus heteroclitus. Parasite communities were classified from 480 individuals representing 15 fish from 4 distinct marsh sites in each of 4 consecutive seasons between 2006 and 2007. Abiotic parameters were recorded at continuous water monitoring stations located at each of the 4 sites. Classification trees identified the presence of benthic invertebrate species (Gammarus sp. and Littorina sp.) as the most important variables in determining parasite presence: secondary splitters were dominated by abiotic variables including conductance, pH and temperature. Seventy percent of hosts were successfully classified into the correct category (infected/uninfected) based on only these criteria. The presence of competent definitive hosts was not considered to be an important explanatory variable. These data suggest that the most important determinant of the presence of these parasite populations in the common killifish is the availability of diverse communities of benthic invertebrates.

scholarly journals Trematode parasite cercariae as food in model freshwater trophic interactions

2021 ◽  
Author(s):  
Ben Schultz
Keyword(s):  
Zooplankton Community ◽  
Life Cycles ◽  
Population Abundance ◽  
Trematode Parasite ◽  
Free Living ◽  
Complex Life Cycles ◽  
Future Studies ◽  
High Consumption ◽  
Daphnia Population ◽  
Trematode Parasites

Free-living parasite stages are important but often overlooked components of ecosystems, especially their role(s) in food webs. Trematode parasites have complex life cycles that include a motile transmission phase, cercariae, that are produced in great quantities within aquatic snail hosts and join the zooplankton community after emerging. Here I examined how cercariae presence affected the population abundance of a common freshwater zooplanktonic animal (Daphnia) when predators were present. I also sought to determine the pathways taken by cercariae-derived carbon within a model freshwater food web by using the stable isotope 13C as a tracer. I found that Daphnia population abundance positively benefitted from cercariae presence when larval dragonfly predators were present, serving as alternate prey. I also found that 13C was an effective tool to track the flow of cercarial carbon, demonstrating high consumption by benthic consumers, as well as the utility of this method for use in future studies.

Complex Life Cycles of Precious and Special Metals

2009 ◽  
pp. 163-197 ◽  
Author(s):  
Christian Hagelüken ◽  
Christina E. M. Meskers
Keyword(s):  
Life Cycles ◽  
Complex Life Cycles
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