Interference with Fasciola hepatica snail finding by various aquatic organisms

Parasitology ◽  
1977 ◽  
Vol 74 (3) ◽  
pp. 285-290 ◽  
Author(s):  
Niels Ørnbjerg Christensen ◽  
Peter Nansen ◽  
Flemming Frandsen
Keyword(s):  
Fasciola Hepatica ◽  
Daphnia Pulex ◽  
Aquatic Organisms ◽  
Host Finding ◽  
Host Snail ◽  
Predatory Behaviour ◽  
Lymnaea Truncatula

Previous studies using radioactive miracidia have shown that a number of non-host snails and bivalves, interposed as ‘decoys’ in linear test channels, may interfere with the capacity of Fasciola hepatica miracidia to infect Lymnaea truncatula. Applying similar experimental principles, the role of several other potential interferents have been analysed in the present study. Daphnia pulex (Cladocera) and larvae of Corethra sp. (Diptera) exercised significant interfering effects by protecting ‘target’ snails from infection. Evidence suggested that this effect was a result of their normal predatory behaviour. Other organisms including Herpobdella testacea and Helobdella stagnalis (Hirudinea), Acellus aquaticus (Isopoda), Planaria lugubris (Turbellaria) and L. Truncatula egg clusters failed to interfere with miracidial host-finding. Nor did P. lugubris and L. truncatula ‘conditioned water’ interfere with the capacity of the miracidia to infect their host snail.

Schistosoma mansoni:interference with cercarial host-finding by various aquatic organisms

1979 ◽  
Vol 53 (1) ◽  
pp. 7-14 ◽  
Author(s):  
N. Ø. Christensen
Keyword(s):  
Lemna Minor ◽  
Daphnia Pulex ◽  
Aquatic Organisms ◽  
Botryococcus Braunii ◽  
Bufo Bufo ◽  
Host Finding ◽  
Ceratophyllum Demersum ◽  
Predatory Behaviour ◽  
Aquatic Vertebrates ◽  
Lebistes Reticulatus

ABSTRACTSchistosoma mansonicercariae labelled with75Se-methionine were used to study host-finding capacity by determining the radioactivity of exposed mouse “target” tails. Possible interfering effects of some aquatic vertebrates and invertebrates, plants and algae and secretions and excretions of aquatic organisms were examined.A marked interferent effect due to predatory behaviour was produced byCyclops strenuus(Copepoda),Daphnia pulexandD. longispina(Cladocera),Notodromas monachaandCypria ophthalmica(Ostracoda) andLebistes reticulatus(guppy).Bufo bufo(Amphibia) andPlanaria lugubris(Turbellaria) interfered significantly, presumably by secreting cercaricidal toxins. Several other organisms apparently produced no interference. The interferent effect of the plant speciesCeratophyllum demersum, Elodea canadensis, Lemna minor, Ranunculus aquaticus, Holcus lanatus(grass) andBotryococcus brauniiwas particularly pronounced when they were confined to the surface layer of the water. Several other species did not interfere with host-finding.

Decoy effect and host infection by miracidia within snail communities

Parasitology ◽  
1993 ◽  
Vol 106 (3) ◽  
pp. 265-276 ◽  
Author(s):  
N. H. Chipev
Keyword(s):  
Developmental Stages ◽  
Fasciola Hepatica ◽  
Host Finding ◽  
Specific Component ◽  
Host Snail ◽  
Decoy Effect ◽  
Individual Host ◽  
Lymnaea Truncatula ◽  
Host Infection ◽  
Distance Response

SUMMARYThe effect of experimental non-host snail (NHS) communities on the infection of Lymnaea truncatula with Paramphistomum daubneyi and Fasciola hepatica miracidia was studied. The results obtained indicated that NHS had variable effects on basic population parameters of host infection. Specifically, NHS were able to produce aggregation of sporocyst number/snail in the experimental host populations. Proposed hypotheses for decoy effect mechanisms failed to explain completely the experimental results. A new mechanism is suggested, based on a distance response of miracidia to snail chemo-attractants, to explain effects of NHS on miracidial host finding behaviour. It is assumed that miracidia have evolved the ability to discriminate among individual snail chemical attractants in a community already at a distance. This attribute of miracidial behaviour allows NHS to induce variations in the effectiveness of individual host localization by miracidia. The resulting aggregation of successful infections/host is assumed to be the specific component of snail decoy effect at the community level. It was also established that NHS affected trematode reproduction in the host inducing a compensatory increase in the intramolluscan population. Intraspecific competition among developmental stages is suggested to be the mechanism of this compensatory reaction.

The relationship between the size of Lymnaea truncatula naturally infected with Fasciola hepatica and the intensity and maturity of the redial infection

1984 ◽  
Vol 58 (2) ◽  
pp. 123-127 ◽  
Author(s):  
Gary Smith
Keyword(s):  
Fasciola Hepatica ◽  
Disease Prevalence ◽  
Similar Data ◽  
Intermediate Hosts ◽  
Primary Host ◽  
Data Set ◽  
Lymnaea Truncatula ◽  
The Mean ◽  
The Relationship

AbstractOf the 2,652 Lymnaea truncatula collected from sites in Cumbria and Gwynedd during 1973–75, when the Prevalence of fascioliasis in the primary host was low and declining, only 123 were infected with Fasciola hepatica. Dissection of these snails revealed that the proportion infected, the mean redial burden and the Proportion of mature rediae in each snail increased with shell length.The results are compared with a similar data set acquired when the prevalence of infection in both the Primary and intermediate hosts was uncharacteristically high. Although the results are qualitatively similar, there are important quantitative differences. The mean redial burden of infected snails at times of high disease Prevalence was generally twice as high as that reported in the present study. It is suggested that differences in habitat microclimate could not account entirely for the observed differences in redial burden and the role of multiple miracidial infection is discussed.

Molluscs interfering with the capacity of Fasciola hepatica miracidia to infect Lymnaea truncatula

Parasitology ◽  
1976 ◽  
Vol 73 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Niels Ørnbjerg Christensen ◽  
Peter Nansen ◽  
Flemming Frandsen
Keyword(s):  
Infection Rate ◽  
Fasciola Hepatica ◽  
Host Finding ◽  
Decoy Effect ◽  
Bithynia Tentaculata ◽  
Lymnaea Truncatula

Fasciola hepatica miracidia labelled with radioselenium were used to study aspects of their host-finding capacity by determining radioactivity subsequently taken up by exposed ‘target’ snails (Lymnaea truncatula). Possible interfering effects exercised by a number of non-host snails and bivalves were examined in linear test channels. The infection rate (radioactivity) among ‘target’ snails was markedly lowered when non-host Lymnaea species (L. pereger, L. palustris, L. stagnalis) were interposed as ‘decoys’. The prosobranch Bithynia tentaculata and the bivalve Sphaeriwm corneum exhibited a slight decoy effect whereas pulmonate species like Anisus vortex, Gyraulus albus, Planorbis planorbis, Physa fontinalis did not interfere with miracidial host-finding.Other experiments showed that miracidia are more strongly attracted towards L. truncatula than L. pereger. Miracidia are not able to penetrate intact egg clusters of L. truncatula.

The influence of some physico-chemical factors on the host-finding capacity of Fasciola hepatica miracidia

1978 ◽  
Vol 52 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Niels Ørnbjerg Christensen ◽  
Peter Nansen ◽  
Flemming Frandsen
Keyword(s):  
Fasciola Hepatica ◽  
Host Finding ◽  
Salinity Level ◽  
Low Salinity ◽  
Physico Chemical ◽  
Lymnaea Truncatula ◽  
Turbidity Level ◽  
Chemical Factors ◽  
High Turbidity ◽  
Ph Range

ABSTRACTA study was made on the host-finding capacity of Fasciola hepatica miracidia in relation to time, number of miracidia per snail, and several physico-chemical environmental factors. Specimens of Lymnaea truncatula were exposed to radiolabelled miracidia and the subsequent snail-bound radioactivity was used to measure the host-finding capacity of the larvae.Maximum snail-bound radioactivity was achieved after 45–60 minutes exposure to miracidia in a volume of 80 ml water. The efficiency of the snail-location was unaltered up to a volume of 4.5 liters. A linear proportionality was demonstrated between the number of miracidia and the amount of radioactivity obtained in exposed snails. After 4 hours exposure snails placed in darkness took up the same amount of radioactivity as snails placed in bright illumination. Additional experiments showed that miracidia preferentially scan the lighted zone of a given environment, but if no snails are available in this zone, snails in shade are also effectively located.The host-finding capacity was unaltered up to a salinity level of 3.79%. At 4.74% and 5.68% the snail-location proceeded at a slower rate, but the final levels reached after 3 hours were comparable to that obtained at low salinity. The over-all host-finding capacity was reduced at a salinity level of 7.58% and at 9.47% the capacity had ceased. The host-finding capacity was unaltered in the pH range 5.4 to 8.4, but it was reduced at pH 8.9. Further studies showed that the host-finding capacity was clearly inhibited in water with a high turbidity level.

Use of odor by host-finding insects: the role of real-time odor environment and odor mixing degree

Chemoecology ◽  
2021 ◽  
Author(s):  
Xinliang Shao ◽  
Ke Cheng ◽  
Zhengwei Wang ◽  
Qin Zhang ◽  
Xitian Yang
Keyword(s):  
Real Time ◽  
Host Finding

scholarly journals The soluble glutathione transferase superfamily: role of Mu class in triclabendazole sulphoxide challenge in Fasciola hepatica

2021 ◽  
Vol 120 (3) ◽  
pp. 979-991
Author(s):  
Rebekah B. Stuart ◽  
Suzanne Zwaanswijk ◽  
Neil D. MacKintosh ◽  
Boontarikaan Witikornkul ◽  
Peter M. Brophy ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Liver Fluke ◽  
Glutathione Transferase ◽  
Fasciola Hepatica ◽  
Affinity Purification ◽  
Economic Loss ◽  
Differential Abundance ◽  
Parasitic Helminths

AbstractFasciola hepatica (liver fluke), a significant threat to food security, causes global economic loss for the livestock industry and is re-emerging as a foodborne disease of humans. In the absence of vaccines, treatment control is by anthelmintics; with only triclabendazole (TCBZ) currently effective against all stages of F. hepatica in livestock and humans. There is widespread resistance to TCBZ and its detoxification by flukes might contribute to the mechanism. However, there is limited phase I capacity in adult parasitic helminths with the phase II detoxification system dominated by the soluble glutathione transferase (GST) superfamily. Previous proteomic studies have demonstrated that the levels of Mu class GST from pooled F. hepatica parasites respond under TCBZ-sulphoxide (TCBZ-SO) challenge during in vitro culture ex-host. We have extended this finding by exploiting a sub-proteomic lead strategy to measure the change in the total soluble GST profile (GST-ome) of individual TCBZ-susceptible F. hepatica on TCBZ-SO-exposure in vitro culture. TCBZ-SO exposure demonstrated differential abundance of FhGST-Mu29 and FhGST-Mu26 following affinity purification using both GSH and S-hexyl GSH affinity. Furthermore, a low or weak affinity matrix interacting Mu class GST (FhGST-Mu5) has been identified and recombinantly expressed and represents a new low-affinity Mu class GST. Low-affinity GST isoforms within the GST-ome was not restricted to FhGST-Mu5 with a second likely low-affinity sigma class GST (FhGST-S2) uncovered. This study represents the most complete Fasciola GST-ome generated to date and has supported the potential of subproteomic analyses on individual adult flukes.

The effects of Fasciola hepatica on Lymnaea truncatula

Parasitology ◽  
1972 ◽  
Vol 65 (2) ◽  
pp. 359-369 ◽  
Author(s):  
J. K. M. Hodasi
Keyword(s):  
Rapid Growth ◽  
Egg Production ◽  
Fasciola Hepatica ◽  
Age Groups ◽  
Sharp Decline ◽  
General Belief ◽  
Functional Changes ◽  
Complete Cessation ◽  
Lymnaea Truncatula ◽  
Accelerated Growth

Among the functional changes observed in L. truncatula infected with F. hepatica were those of growth, reproduction and mortality. For the first 3 weeks after infection there was no difference between the growth of infected and uninfected groups of snails. Thereafter there was a temporary accelerated growth which occurred between the fourth and seventh weeks after infection. The onset of this period of rapid growth in the different age groups of infected snails coincided with the time of migration of the rediae into the hepatopancreas. Of more significance was the influence of infection on the reproduction of the snail. There was a sharp decline in oviposition 2–3 weeks after infection, followed by a complete cessation of egg production at the end of the fifth week. Once oviposition ceased, it was not resumed and there was no self-cure. Contrary to general belief, infected groups of L. truncatula have been found to live longer than the uninfected controls. With isolated snails, however, there was a tendency for the uninfected snails to live longer than the infected ones. The possible interpretation of the discrepancies between isolated and mass cultured snails are discussed. The hepatopancreas and the gonad (ovotestis) were the two structures directly affected by the infection. Establishment of the rediae in the hepatopancreas invariably resulted in parasitic castration.

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