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PubMed1981

The different stages of Fasciola hepatica capable of inducing immunity and the susceptibility of various stages to immunological attack in the sensitised rat.

Intraperitoneal sensitisation of female Piebald Virol Glaxo rats by the migratory immature stages (two-hours-, six-days- and 14-days-old) of the liver fluke Fasciola hepatica protected them from intraperitoneal challenge with living adult flukes three weeks later. Sensitisation with adult fluke antigen and Freund's complete adjuvant had no effect. Flukes attenuated by gamma irradiation (3-8 kiloroentgen), and so prevented from developing beyond the eight to 10 day stage, did not protect against adult challenge. When rats were sensitised orally with metacercariae and challenged with 14-day-old flukes intraperitoneally the challenge flukes were not adversely affected. It is suggested that although 14-day-old flukes can immunise rats adequately, the fact that they are not killed when placed in sensitised rats may be due to the protective effect of tegumental replacement in these flukes before gaining access to, and safety of, the liver site.

Animals↗
PubMed1996

Seasonal transmission of Fasciola hepatica in Montana, USA, with detection of infected intermediate hosts using a DNA-based assay.

A cashmere goat ranch in the Beaverhead Valley, southwest Montana, USA reported acute fasciolosis in March 1992. The ranch was used as a study site to gather seasonal transmission data for the liver fluke, Fasciola hepatica. Testing of snails for infection with a nucleic acid-based assay, and use of tracer sheep at the site has shown the seasonal transmission of the parasite is only in late autumn. The snail responsible for transmission was identified as Lymnaea modicella although another known intermediate host species, Lymnaea bulimoides, was found in one collection at the study site. Tracer sheep used over a 12-month period became infected with F. hepatica while on pasture during a period between September 10 and November 12, 1993. During the 28 months of study, 3072 individual lymnaeid snails were tested for infection. One sample of L. modicella containing 25 snails, collected in August 1994 contained liver fluke ribosomal RNA.

Animals↗
PubMed2006

Fasciola hepatica: ultrastructural effects of a combination of triclabendazole and clorsulon against mature fluke.

A study has been carried out to investigate the ultrastructural effects of triclabendazole (TCBZ) at half-normal concentration, clorsulon at half-normal concentration, and a combination of these two drugs against mature Fasciola hepatica. The Cullompton TCBZ-susceptible isolate was used for these experiments. Flukes were incubated for 24 h in vitro in TCBZ sulphoxide (7.5 microg/ml), clorsulon (5 microg/ml), or a combination of the two drugs. For the in vivo experiment, rats were dosed with TCBZ (5 mg/kg body weight), clorsulon (5 mg/kg body weight), or a combination of the two drugs, and flukes recovered after 48 h. Fine structural changes within the tegumental syncytium and tegumental cells were assessed by transmission electron microscopy. Treatment with the combination of drugs produced greater disruption to the flukes than the individual drugs at half-normal concentrations, both in vivo and in vitro; also than TCBZ.SO at normal concentration in vitro. The changes observed aid in the understanding of the gross changes to the tegumental surface described previously (Meaney M, Allister J, McKinstry B, McLaughlin K, Brennan GP, Forbes AB, Fairweather I. Parasitol Res 99:609-621, 2006). The results indicate that there are additive effects between TCBZ and clorsulon and suggest that the use of drug combinations would be of value in the treatment of TCBZ-resistant fluke.

Animals↗
PubMed2003

Fasciola hepatica: surface and internal tegumental changes induced by treatment in vitro with the sulphoxide metabolite of albendazole ('Valbazen').

A morphological study has been carried out to determine the effect of the active sulphoxide metabolite of the benzimidazole anthelmintic, albendazole (ABZ-SO) on the adult liver fluke, Fasciola hepatica. Whole flukes were treated with ABZ-SO for 12 and 24 h at a concentration of 10 microg/ml. The changes in response to drug treatment were examined by scanning electron microscopy (SENI), transmission electron microscopy (TEM) and tubulin immunocytochemistry (ICC). No surface changes were apparent following 12 h ABZ-SO treatment, but localized blebbing was observed after 24 h, which became more extensive towards the posterior region of both surfaces. TEM of sections from the posterior midbody region revealed that ABZ-SO caused the accumulation of secretory bodies in the tegumental cells and in their cytoplasmic connections and, after 24 h, just above the basal plasma membrane. Localized blebbing of the apical membrane also occurred. The morphology of the Golgi complexes within the tegumental cells began to change after 12 h treatment with ABZ-SO and, by 24 h, few complexes were observed. A distinct increase in tubulin immunoreactivity occurred after 12 h treatment, but this decreased after 24 h. The results obtained are consistent with those expected for microtubule inhibition. They are discussed in relation to the action of established microtubule inhibitors, as well as the benzimidazole derivative, triclabendazole.

Albendazole↗
PubMed2002

Unusual snail species involved in the transmission of Fasciola hepatica in watercress beds in central France.

Four freshwater pulmonate species (Lymnaea ovata, L. stagnalis, Physa acuta, Planorbis leucostoma) were living in several watercress beds known for their relationships with human cases of fasciolosis, whereas L. truncatula was never found. The aims of these studies were to determine the prevalence of natural infections with Fasciola hepatica in snails and to verify if these species might ensure the full larval development of this trematode (with cercarial shedding) when they were experimentally subjected to F. hepatica only, or to co-infections with an other trematode species. Investigations were so carried out in six snail populations living in watercress beds (including three for P. acuta) and in four others originating from three brooks or a pond (as controls). Snails naturally infected with F. hepatica were found in two watercress beds inhabited by L. ovata (prevalence of infection: 1.4%) and P. leucostoma (0.1%), respectively. The L. ovata from the watercress bed could be infected at a higher size than those from the control population and the prevalence of this infection was greater in the bed population. Similar findings were noted for L. stagnalis. Despite single or dual infections, the results obtained with the four populations of P. acuta were unsuccessful. In contrast, the co-infections of young P. leucostoma with Paramphistomum daubneyi and F. hepatica resulted in the shedding of some F. hepatica cercariae. According to the authors, the occurrence of fasciolosis in these watercress beds would be the consequence of frequent natural encounters between parasite and snails (L. ovata, L. stagnalis), or of co-infections with P. daubneyi and F. hepatica (P. leucostoma). In watercress beds only colonized by P. acuta, a lymnaeid species would have ensured the larval development of F. hepatica but it would have been eliminated by P. acuta, as this last species was known to be invasive and could colonize open drainage ditches on siliceous soil.

Animals↗
PubMed1991

Survival of snails and characteristic lesions of Fasciola hepatica infection in four European species of Lymnaea.

The survival of snails and characteristic organ lesions were investigated in four different age categories (new-born, 1 and 2 mm shell height, adults) and in four species of Lymnaea (L. glabra, L. palustris, L. peregra ovata, L. truncatula) infected by Fasciola hepatica. Mortalities were higher in infected groups on Days 30 and 45 post-infection (+42% and +45%, respectively) than in controls. Lesions depended on the species and age of the Lymnaea. Epithelial necrosis of the kidney was recorded in L. glabra, L. palustris and L. p. ovata, whereas intralamellar deposits were found in the same organ of L. truncatula. All categories of L. truncatula had evolutive infections (snails with living parthenitae); the young snails of other species became infected, but the adults did not, as estimated at Day 45 post-infection. The lesions were related to the intensity of evolutive infections: necrosis of the digestive gland was found in moderate to low infections and, conversely, gonadal atrophy with epithelial necrosis was found in highly infected snails.

Animals↗
PubMed1986

Nuclear magnetic resonance studies of carbohydrate metabolism and substrate cycling in Fasciola hepatica.

We have been interested in clarifying unique features of glycolytic metabolism in parasitic trematodes and in developing improved methods for monitoring the effects of pharmacologic agents that may alter functions of the pathway. In the present study metabolism of [1-13C]glucose by the common liver fluke, Fasciola hepatica, was studied both directly with 13C NMR and indirectly by observation of 13C-induced multiplet splitting of the 1H NMR resonances from the glycolytic end-products propionate and acetate. The extent of 13C enrichment of the end-products demonstrated that exogenous glucose was the predominant source of glycolytic substrate under the incubation conditions used. Specific enrichments of propionate and acetate in 13C were similar and enrichments at the acetate C-1 carboxyl and C-2 methyl were identical, demonstrating that acetate is generated preferentially from pyruvate formed by the malic enzyme reaction. End-product synthesized in substrate-free medium following incorporation of a small fraction of [1-13C]glucose into endogenous glycogen demonstrates that glucose equivalents from the most recently synthesized polymeric chains, which have a specific activity in 13C equal to that of the exogenous glucose, are preferentially used for glycogenolysis. Stimulation of flukes with 0.1 mM serotonin results in a reduction of the propionate/acetate 13C enrichment ratio consistent with functional "compartmentation" of glycogen pools having different structures and/or specific enrichment in 13C. Glucose equivalents were incorporated into glycogen in intact flukes with label at both the C-1 and C-6 positions during perfusion with [1-13C]glucose as a consequence of "substrate cycling" at the phosphofructokinase/fructosebisphosphatase enzyme couple. The observed glycogen C-6/C-1 labeling ratio of 0.42 and the net glycolytic flux of 11 mumol/g wet weight/hr imply a total forward flux of about 29 mumol/g wet weight/hr through phosphofructokinase with a reverse flux of about 17 mumol/g wet weight/hr through fructosebisphosphatase. Net glycolytic flux is therefore a poor estimate of the true flux through phosphofructokinase in this preparation.

Acetates↗
PubMed1982

[Redial generations of Fasciola hepatica L. in Lymnaea truncatula Müller apropos of the effects of several factors].

There was a succession of 3 redial generations in 4-mm-high snails individually exposed to a single miracidium and then bred at 20 degrees C during 30 days after exposure. The geographic strain of miracidia of Fasciola hepatica had no influence on the development of these redial generations. The succession of these redial generations changed in the case of plurimiracidial exposures. In snails once exposed to high numbers of miracidia (from 5 to 20), the mean number of rediae per snail decreased affecting especially the generations 2 and 3; the maturation of rediae of generations 1 and 2 was later when the number of used miracidia was higher. The same results were found in snails individually subjected to 4 exposures with one miracidium per exposure. The significance of these observations is discussed.

Animals↗
PubMed1980

Effects of Fasciola hepatica infection on responses of rats to reinfection with Salmonella dublin.

The survival rate of rats given potentially lethal doses of 7.6 X 10(8) to 10(9) Salmonella dublin intraperitoneally was enhanced in those which had been infected six weeks previously with 10(2) S dublin by the same route. Fasciola hepatica given six weeks before or one week after 10(2) S dublin did not alter the survival rate of rats reinfected with S dublin. However high levels (10(4) to 10(6) per g) of S dublin persisted in the tissues and faeces of fluke-infected but not of fluke-free rats. Agglutinating antibody responses to S dublin were unimpaired in fluke-infected rats but cutaneous delayed hypersensitivity reactions were slightly reduced. the humoral agglutinating antibody response may be important for survival of the host but other responses may be necessary for elimination of S dublin from the tissues.

Agglutinins↗
PubMed2000

Histopathological and immunohistochemical study of lambs experimentally infected with Fasciola hepatica and Schistosoma bovis.

The aim of this study was to investigate the cross-resistance between Fasciola hepatica and Schistosoma bovis in lambs assessing parasitologic, gross pathologic, histopathologic and immunohistochemical changes in liver and small intestine. Thirty Castellana breed lambs were divided into five comparable groups and exposed to F. hepatical S. bovis (group F/S), S. bovis/F. hepatica (group S/F), S. bovis (group S) or F. hepatica (group F) and six unexposed lambs were used as non-infected controls (group C). Primary patent infection with F. hepatica induced a lower number of schistosome eggs and a higher number of lymphocytes in intestinal and liver schistosome egg-induced granulomas in group F/S than in the groups S/F and S, liver damage being mainly attributed to F. hepatica. S. bovis infection followed by challenge with F. hepatica particularly increased the severity of the most significant liver alterations (cholangiohepatitis by F. hepatica and mesoendophlebitis by S. bovis) and F. hepatica seemed not to have an influence on established S. bovis infection. In addition, immunohistochemical results suggested that the predominant local immune response in both double-infected groups was different, being mainly a cell-mediated immune response in group F/S and a mucosal response in group S/F.

Animals↗
PubMed2003

[Prevalence of Fasciola hepatica and Dicrocoelium dendriticum in the cow: inspection in an east Switzerland abattoir].

On the basis of meat inspection in an abattoir in the eastern part of Switzerland, the incidence of liverflukes in cattle was recorded weekly during one year. The prevalence was compared with surveys from the seventies and nineties. The average incidence of Dicrocoelium dendriticum infection did not change. Although the prevalence of Fasciola hepatica apparently slightly decreased, an actual decrease of liverflukes could not be demonstrated.

Abattoirs↗
PubMed2003

The presence of Fasciola hepatica (liver-fluke) in humans and cattle from a 4,500 year old archaeological site in the Saale-Unstrut valley, Germany.

During an excavation of a site of the corded ware culture in the Saale-Unstrut-Valley (ca. 3000 BC) in Germany, a soil sample from the pelvis of a human skeleton was studied under palaeoparasitological aspects. Eggs of the trematode Fasciola hepatica and of the nematode genus Capillaria were found. This is the first case of a direct association of a F. hepatica-infestation to both a prehistoric human skeleton and domesticated animal remains. Sheep and cattle bones were present at the same site and F. hepatica eggs were found in bovine samples. This strongly points toward an existing infection cycle, involving humans as a final host.

Animals↗
PubMed1985

Induction of immunity in mice to Fasciola hepatica with a Fasciola/Schistosoma cross-reactive defined immunity antigen.

The paradox of schistosomiasis is that infection confers immunity to its host, yet immunization with subcellular antigens of the parasite does not, in general, induce protective immunity. Infection or immunization with subcellular antigens of Fasciola hepatica confers high levels of immunity to a challenge infection with another trematode, Schistosoma mansoni. We have isolated by antibody affinity chromatography a Fasciola hepatica/Schistoma mansoni cross-reactive antigen, designated FhSmIII(M), and also have shown that this antigen confers immunity in mice to a challenge infection with S. mansoni. This antigen was compared with a crude F. hepatica worm extract (FhWWE) as to its ability to induce an IgG antibody response in mice, and to determine whether it had a protective effect in mice to a challenge infection with F. hepatica metacercariae. Mice immunized with FhSmIII(M) or FhWWE, and subsequently infected with F. hepatica, developed higher IgG antibody levels to FhSmIII(M), as measured by ELISA, than F. hepatica-infected controls. Mice immunized with FhWWE did not develop significant levels of resistance to challenge with F. hepatica metacercariae. Mice immunized with FhSmIII(M) and infected with F. hepatica metacercariae developed 69%-78% less worms than controls. An F. hepatica/S. mansoni cross-reactive, cross-protective defined immunity antigen confers in mice significant levels of protection to a challenge infection with F. hepatica.

Animals↗