scholarly journals When should a trophically and vertically transmitted parasite manipulate its intermediate host? The case of Toxoplasma gondii

2013 ◽  
Vol 280 (1765) ◽  
pp. 20131143 ◽  
Author(s):  
Maud Lélu ◽  
Michel Langlais ◽  
Marie-Lazarine Poulle ◽  
Emmanuelle Gilot-Fromont ◽  
Sylvain Gandon
Keyword(s):  
Toxoplasma Gondii ◽  
Vertical Transmission ◽  
Death Rate ◽  
Predation Rate ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Virulent Strains ◽  
Host Behaviour ◽  
Different Levels

Parasites with complex life cycles are expected to manipulate the behaviour of their intermediate hosts (IHs), which increase their predation rate and facilitate the transmission to definitive hosts (DHs). This ability, however, is a double-edged sword when the parasite can also be transmitted vertically in the IH. In this situation, as the manipulation of the IH behaviour increases the IH death rate, it conflicts with vertical transmission, which requires healthy and reproducing IHs. The protozoan Toxoplasma gondii , a widespread pathogen, combines both trophic and vertical transmission strategies. Is parasite manipulation of host behaviour still adaptive in this situation? We model the evolution of the IH manipulation by T. gondii to study the conflict between these two routes of transmission under different epidemiological situations. Model outputs show that manipulation is particularly advantageous for virulent strains and in epidemic situations, and that different levels of manipulation may evolve depending on the sex of the IH and the transmission routes considered. These results may help to understand the variability of strain characteristics encountered for T. gondii and may extend to other trophically transmitted parasites.

Behavioural and physiological effects of the trophically transmitted cestode parasite, Cyathocephalus truncatus, on its intermediate host, Gammarus pulex

Parasitology ◽  
2007 ◽  
Vol 134 (12) ◽  
pp. 1839-1847 ◽  
Author(s):  
N. FRANCESCHI ◽  
T. RIGAUD ◽  
Y. MORET ◽  
F. HERVANT ◽  
L. BOLLACHE
Keyword(s):  
Behavioural Change ◽  
Predation Rate ◽  
Life Cycles ◽  
Gammarus Pulex ◽  
Intermediate Hosts ◽  
Host Reaction ◽  
Complex Life Cycles ◽  
Cestode Parasite ◽  
Behavioural Manipulation ◽  
Pathogenic Effects

SUMMARYSome parasites with complex life-cycles are able to manipulate the behaviour of their intermediate hosts in a way that increases their transmission to the next host. Gammarids infected by the tapeworm Cyathocephalus truncatus (Cestoda: Spathebothriidea) are known to be more predated by fish than uninfected ones, but potential behavioural manipulation by the parasite has never been investigated. In this study, we tested the hypothesis that C. truncatus is able to manipulate the behaviour of one of its intermediate hosts, Gammarus pulex (Crustacea: Amphipoda). To assess if any behavioural change was linked to other phenotypic alterations, we also measured the immunity of infected and uninfected individuals and investigated the pathogenic effects of the parasite. Infected gammarids were significantly less photophobic than uninfected ones, but no effect of infection on the level of immune defence was found. The results on survival, swimming activity and oxygen consumption suggest that the parasite also has various pathogenic effects. However, the alteration in host phototaxis was not correlated to some of these pathogenic effects. Therefore, we propose that the modification in host reaction to light is a behavioural manipulation, explaining the previously observed increase of gammarid predation rate.

Insights into the molecular basis of host behaviour manipulation by Toxoplasma gondii infection

2017 ◽  
Vol 1 (6) ◽  
pp. 563-572 ◽  
Author(s):  
Pierre-Mehdi Hammoudi ◽  
Dominique Soldati-Favre
Keyword(s):  
Toxoplasma Gondii ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Brain Regions ◽  
Intermediate Hosts ◽  
Toxoplasma Gondii Infection ◽  
Host Parasite ◽  
Host Behaviour ◽  
The Brain ◽  
Brain Homeostasis

Typically illustrating the ‘manipulation hypothesis’, Toxoplasma gondii is widely known to trigger sustainable behavioural changes during chronic infection of intermediate hosts to enhance transmission to its feline definitive hosts, ensuring survival and dissemination. During the chronic stage of infection in rodents, a variety of neurological dysfunctions have been unravelled and correlated with the loss of cat fear, among other phenotypic impacts. However, the underlying neurological alteration(s) driving these behavioural modifications is only partially understood, which makes it difficult to draw more than a correlation between T. gondii infection and changes in brain homeostasis. Moreover, it is barely known which among the brain regions governing fear and stress responses are preferentially affected during T. gondii infection. Studies aiming at an in-depth dissection of underlying molecular mechanisms occurring at the host and parasite levels will be discussed in this review. Addressing this reminiscent topic in the light of recent technical progress and new discoveries regarding fear response, olfaction and neuromodulator mechanisms could contribute to a better understanding of this complex host–parasite interaction.

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 Cancer in the parasitic protozoans Trypanosoma brucei and Toxoplasma gondii

2015 ◽  
Vol 112 (29) ◽  
pp. 8835-8842 ◽  
Author(s):  
Zhao-Rong Lun ◽  
De-Hua Lai ◽  
Yan-Zi Wen ◽  
Ling-Ling Zheng ◽  
Ji-Long Shen ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Trypanosoma Brucei ◽  
Severe Disease ◽  
Life Cycles ◽  
Model Systems ◽  
Suitable Model ◽  
Complex Life Cycles ◽  
Obligate Intracellular ◽  
Obligate Intracellular Pathogen ◽  
Made In

Cancer is a general name for more than 100 malignant diseases. It is postulated that all cancers start from a single abnormal cell that grows out of control. Untreated cancers can cause serious consequences and deaths. Great progress has been made in cancer research that has significantly improved our knowledge and understanding of the nature and mechanisms of the disease, but the origins of cancer are far from being well understood due to the limitations of suitable model systems and to the complexities of the disease. In view of the fact that cancers are found in various species of vertebrates and other metazoa, here, we suggest that cancer also occurs in parasitic protozoans such as Trypanosoma brucei, a blood parasite, and Toxoplasma gondii, an obligate intracellular pathogen. Without treatment, these protozoan cancers may cause severe disease and death in mammals, including humans. The simpler genomes of these single-cell organisms, in combination with their complex life cycles and fascinating life cycle differentiation processes, may help us to better understand the origins of cancers and, in particular, leukemias.

Pan-American marine coastal distribution of the acanthocephalan Profilicollis altmani based on morphometric and phylogenetic analyses of cystacanths from the mole crab Emerita brasiliensis

2016 ◽  
Vol 91 (3) ◽  
pp. 371-375 ◽  
Author(s):  
S.M. Rodríguez ◽  
G. D'Elía
Keyword(s):  
Phylogenetic Analyses ◽  
Atlantic Coast ◽  
Life Cycles ◽  
Morphological Evidence ◽  
South American ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Present Complex ◽  
The World ◽  
Pan American

AbstractThorny-headed acanthocephalan worms of the genus Profilicollis are widely distributed in the oceans of the world and present complex life cycles with intermediate and definitive hosts. The genus is still poorly known, with an unstable taxonomy and, for most species, incompletely characterized geographical distributions. In this study, based on molecular and morphological evidence, we report that the species Profilicollis altmani is also distributed along the South American Atlantic coast, using the mole crab Emerita brasiliensis as an intermediate host. As such, our record shows that P. altmani has a Pan-American distribution where five species of Emerita are utilized as intermediate hosts.

scholarly journals In Vivo and In Vitro Virulence Analysis of Four Genetically Distinct Toxoplasma gondii Lineage III Isolates

2020 ◽  
Vol 8 (11) ◽  
pp. 1702
Author(s):  
Aleksandra Uzelac ◽  
Ivana Klun ◽  
Vladimir Ćirković ◽  
Olgica Djurković-Djaković
Keyword(s):  
Toxoplasma Gondii ◽  
Underlying Mechanism ◽  
Domestic Animals ◽  
Intermediate Hosts ◽  
Stage Conversion ◽  
Virulence Analysis ◽  
Virulent Strains ◽  
Distinct Lineage

Toxoplasma gondii archetypes II and III are mildly virulent, yet virulence of variant strains is largely unknown. While lineage II dominates in humans in Europe, lineage III strains are present in various intermediate hosts. In Serbia, lineage III represents 24% of the population structure and occurs most frequently in domestic animals, implying a significant presence in the human food web. In this study, the virulence of four genetically distinct lineage III variants was assessed in vivo and in vitro. In vivo, two strains were shown to be intermediately virulent and two mildly virulent, with cumulative mortalities of 69.4%, 38.8%, 10.7%, and 6.8%, respectively. The strain with the highest mortality has previously been isolated in Europe and may be endemic; the strain with the lowest mortality matches ToxoDB#54, while the remaining two represent novel genotypes. Identical alleles were detected at ROP5, ROP16, ROP18, and GRA15. A set of in vitro analyses revealed proliferation and plaque formation as virulence factors. Higher levels of expression of ENO2 in intermediately virulent strains point to enhanced metabolism as the underlying mechanism. The results suggest that metabolic attenuation, and possibly stage conversion, may be delayed in virulent strains.

scholarly journals Parasite-modified behaviour in non-trophic transmission: trematode parasitism increases the attraction between snail intermediate hosts

2020 ◽  
Vol 98 (7) ◽  
pp. 417-424
Author(s):  
L.K. Eliuk ◽  
S. Brown ◽  
R.C. Wyeth ◽  
J.T. Detwiler
Keyword(s):  
Life Cycles ◽  
Intermediate Hosts ◽  
Free Swimming ◽  
Complex Life Cycles ◽  
Trophic Transmission ◽  
Y Maze ◽  
Second Intermediate Host ◽  
Behavioural Experiments ◽  
Lymnaea Elodes ◽  
Host Parasite

Many parasites with complex life cycles cause host behavioural changes that increase the likelihood of transmission to the next host. Parasite modification is often found in trophic transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic, suggesting that free-swimming larvae (cercariae) emerging in closer proximity to the next host would have higher transmission success. We performed a series of behavioural experiments with echinostome trematodes and their snail hosts to determine if potential second hosts (ramshorn snail, genus Planorbella Haldeman, 1842) were more attracted to parasitized first hosts (marsh pondsnail, Lymnaea elodes Say, 1821). In a Y maze, a responding snail (Planorbella sp.) was placed in the base and its response to five treatments was assessed: no stimulus, turion duckweed (Lemna turionifera Landolt; a food item), non-parasitized L. elodes, parasitized L. elodes, and finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to uninfected snails, but had a stronger response to infected first host snails. These results indicate that potential second host snails were more attracted to parasitized, heterospecific first host snails over non-parasitized heterospecific snails. This study demonstrates that echinostome trematodes alter snail behaviour by changing navigational choices in uninfected potential hosts through a chemical communication mechanism.

scholarly journals Testing the parasite mass burden effect on host behaviour alteration in the Schistocephalus-stickleback system

2017 ◽  
Author(s):  
Lucie Grécias ◽  
Julie Valentin ◽  
Nadia Aubin-Horth
Keyword(s):  
Gasterosteus Aculeatus ◽  
Behavioural Change ◽  
Body Cavity ◽  
Mechanical Effect ◽  
Life Cycles ◽  
Fish Host ◽  
The Body ◽  
Complex Life Cycles ◽  
Internal Parasite ◽  
Host Behaviour

ABSTRACTMany parasites with complex life cycles modify their intermediate host’s behaviour, which has been proposed to increase transmission to their definitive host. This behavioural change could result from the parasite actively manipulating its host, but could also be explained by a mechanical effect, where the parasite’s physical presence affects host behaviour. We created an artificial internal parasite using silicone injections in the body cavity to test this mechanical effect hypothesis. We used the Schistocephalus solidus - threespine stickleback (Gasterosteus aculeatus) system, as this cestode can reach up to 92% of its fish host mass. Our results suggest that the mass burden brought by this macroparasite alone is not sufficient to cause behavioural changes in its host. Furthermore, our results show that wall-hugging (thigmotaxis), a measure of anxiety in vertebrates, is significantly reduced in Schistocephalus-infected sticklebacks, unveiling a new altered component of behaviour that may result from manipulation by this macroparasite.

scholarly journals Toxoplasma gondii in house mice Mus musculus domesticus from Dakar, Senegal: clues for oral rather than vertical mode of infection

2019 ◽  
Author(s):  
Lokman Galal ◽  
Claire Stragier ◽  
Farid Boumediène ◽  
Azra Hamidović ◽  
Océane Maugrion ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Vertical Transmission ◽  
Mus Musculus ◽  
Spatial Location ◽  
Oral Route ◽  
Mus Musculus Domesticus ◽  
Single Family ◽  
Intermediate Hosts ◽  
Host Genotype ◽  
Commensal Rodents

AbstractToxoplasma gondii is an ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main preys of cats, are probably the major reservoir for T. gondii. Rodents often develop dormant tissue cysts after ingestion of oocysts shed in the environment by cats in the form of contaminated feces. Experimental evidence that vertical transmission can be sufficient to the perpetuation of transmission between generations of mice has also been found. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse Mus musculus domesticus is the predominant putative reservoir of T. gondii. Host genotype and spatial location through GPS referencing of all trapping localizations were investigated in relation to T. gondii infection in 12 sites of the city of Dakar and on Goree Island. In each sampled site, the occurrence of over-prevalence zones of T. gondii infection was investigated through Kulldorf’s statistic using SaTScan software. For the sites where a possible over-prevalence zone was identified, mice family lines were inferred from Discriminant Analysis of Principal Components (DAPC). In 3 of the 4 identified possible over-prevalence zones, T. gondii infection was not confined to a single family line, which suggested no association between kinship and infection occurrence. This finding rather suggests an environmental source of infection for mice associated with localized putative foci of environmental contamination and supports an oral route of infection for mice from Dakar rather than a cycle based on vertical transmission.

Tranmission pattern differences of miracidia and cercariae larval stages of digenetic trematode parasites

2016 ◽  
Vol 61 (4) ◽  
Author(s):  
Michael R. Zimmermann ◽  
Kyle E. Luth ◽  
Gerald W. Esch
Keyword(s):  
Abiotic Factors ◽  
Field Studies ◽  
Life Cycles ◽  
Digenetic Trematode ◽  
Snail Species ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Larval Stages ◽  
Digenetic Trematodes ◽  
Trematode Parasites

AbstractDigenetic trematodes have complex life cycles involving multiple hosts and free-living larval stages. Some species have 2 lar-val stages that infect snails, with miracidia and cercariae using these molluscs as first and second intermediate hosts, respec-tively. Although both larval stages may infect the same snail species, this is accomplished using different chemical cues and may be influenced by different biotic and abiotic factors. Significant differences in the infection patterns of these parasitic stages regarding host size and density were observed in 2 separate field studies. The prevalence of sporocysts/rediae and mean abundance of

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