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PubMed1982

Plasma ascorbic acid levels in sheep experimentally infected with Fasciola hepatica.

Three groups of sheep, one control (A) and two infected with Fasciola hepatica metacercariae (B&C), were investigated. Each animal of group B was orally dosed with about 270 metacercariae and each sheep in group C received two such doses administered 14 days apart. In both infected groups, plasma ascorbic acid levels progressively decreased after exposure reaching a minimum by week 9, and then slightly increased during the subsequent five weeks. The decrease in ascorbic acid concentrations was mainly related to impaired synthesis as a result of the hepatic damage caused by the flukes.

Animals↗
PubMed1981

Further studies on resistance to Fasciola hepatica and Echinostoma revolutum in mice infected with Schistosoma sp.

Schistosoma sp. induced cross-resistance to a challenge with Fasciola hepatica and Echinostoma revolutum was studied in mice. Primary patent 56-days-old S. intercalatum and S. bovis infections stimulated a statistically significant level of resistance to a challenge with F. hepatica, and primary patent 100-day-old S. bovis infections induced an almost complete resistance to a challenge with E. revolutum. Primary single-sex S. mansoni infections, either male or female, aged 90 days did not stimulate any resistance to a challenge with E. revolutum. A primary infection with S. mansoni aged 70 days induced a marked reduction (94.1--100%) in the E. revolutum worm recovery already 2 h post-challenge as compared with that of the E. revolutum challenge control group and complete elimination of the echinostome worm population in S. mansoni infected mice had taken place 24 h after challenge. E. revolutum worm populations established in mice harbouring newly patent 36-day-old S. mansoni infections persisted unchanged for a period of at least 33 days into the patent period of the schistosome infection in spite of development of a complete resistance to a challenge with E. revolutum metacercariae during this period.

Animals↗
PubMed1979

Effect of BCG on the resistance of rats to infection with Fasciola hepatica.

The effects of three different doses of BCG, given at various periods before infection, on the subsequent establishment of Fasciola hepatica metacercariae were studied. Although evidence was found to suggest that rats which received BCG had mounted a cell mediated immune response, there were no significant differences in worm recovery between BCG-treated rats and controls. The significance of these results in the light of current knowledge on immunity to F. hepatica in rats is discussed.

Animals↗
PubMed1990

The effect of the hydrogen ionophore closantel upon the pharmacology and ultrastructure of the adult liver fluke Fasciola hepatica.

The present study describes the effects of the H+ ionophore and anthelmintic closantel upon the in vitro motility and in vivo ultrastructure of the liver fluke, Fasciola hepatica. At a concentration of 50 micrograms/ml, closantel caused an initial stimulation, then suppression of activity, which was accompanied by an increase in muscle tone and led to a spastic paralysis within 2 h. The pattern of response was similar at lower concentrations, although the initial stimulation was not always evident, but the onset of paralysis could be reached more quickly. Scanning electron microscopy revealed gross surface damage from 24 h onwards in vivo, in the form of erosion of the anterior and posterior extremities of the fluke and large-scale sloughing of the tegument on both dorsal and ventral surfaces. Tegumental changes prior to sloughing included some swelling of the basal infolds and an apical accumulation of T1 secretory bodies. In the underlying tegumental cells there was reduced secretory activity and the mitochondria were consistently swollen and deformed. Reduced secretory activity was a feature of the gastrodermal cells as well; these cells were characterized by swollen, electron-lucent mitochondria, vesiculated GER cisternae and apical blebbing of packets of cytoplasm. The vitelline follicles became severely disrupted as a result of the breakdown of the nurse cell cytoplasm. The stem and intermediate type 1 (It1) cells rounded up and showed nuclear abnormalities. There did not appear to be a severe disruption of shell protein production in the intermediate vitelline cells, but there was a noticeable absence of glycogen in the mature vitelline cells. The effects of closantel are discussed in relation to its proposed mode of action as an uncoupler of oxidative phosphorylation.

Animals↗
PubMed1988

Activity of luxabendazole against liver flukes, gastrointestinal roundworms, and lungworms in naturally infected sheep.

The anthelmintic potential of luxabendazole was investigated in sheep harboring mixed naturally acquired helminth infections. Results were assessed by comparing worm counts of the treated groups (seven animals each) on days 7-8 posttreatment with those of the nontreated control group, except for protostrongylid lungworms, for which the changes in pre- and posttreatment group mean larval counts/g feces were assessed for intensity effect. A single oral treatment at doses of 10.0 or 12.5 mg/kg body wt removed 97.6% of the adult Fasciola hepatica and 63.2%-83.8% of the Dicrocoelium dendriticum. Luxabendazole at 7.5, 10.0, and 12.5 mg/kg proved 100% effective in removing adult worms of the genera Haemonchus, Ostertagia, Trichostrongylus, Cooperia and Nematodirus as well as tissue-associated larval stages of gastrointestinal nematodes of the abomasal mucosa. The drug showed an intensity effect of 79.7%-87.6% against Strongyloides papillosus. Luxabendazole removed all Dictyocaulus filaria and reduced the fecal excretion of larvae of protostrongylid species (Protostrongylus rufescens, Neostrongylus linearis, Cystocaulus ocreatus, Muellerius capillaris) by 97.8%-99.6%. The efficacy of luxabendazole compared favorably with that of Diplin Kombi (oxyclozanide and levamisole), which was used as a reference drug.

Abomasum↗
PubMed1995

Ionic composition of the liver fluke Fasciola hepatica from different mammalian hosts and comparison with host bile.

A qualitative analysis of the cationic profile of bovine and ovine biles and of bovine, ovine and rat liver flukes has been carried out by DC arc emission spectrography. A quantitative assessment of the concentrations of Na+, K+, Ca2+ and Mg2+ ions in bovine, ovine and rat flukes has been determined by atomic absorption spectrophotometry. The levels of these ions in bovine and ovine bile samples have also been assessed and compared with those of Hédon-Heig saline. The ionic composition of the two biles is similar and the concentration of each ion is greater than that in Hédon-Heig saline. Despite the similarity in biles, ion levels in bovine flukes are generally higher than those in ovine flukes. Ion levels in rat flukes are different again but show closer similarity to those in bovine, not ovine, flukes. The results are discussed in relation to the proposed operation of the osmoregulatory system in the fluke.

Animals↗
PubMed1995

The effects of subclinical fasciolosis on hepatic secretory function in sheep.

The effects of subclinical fasciolosis at various stages of its development on bile flow and bile acid secretion and on the hepatobiliary transport of bilirubin were investigated in experimentally infected sheep. Bile flow was significantly reduced by weeks 6-14 postinfection. This was accompanied by a decrease in bile acid secretion by weeks 6-8. Serum AST and GLDH activities and serum bile acid concentration were significantly elevated from weeks 6 to 14. Total serum bilirubin was maximally increased at 6 weeks postinfection and remained elevated at weeks 8 and 14. Increases corresponded to both unconjugated and conjugated fractions, although the conjugated/total bilirubin ratio was enhanced in all infected animals. Biliary bilirubin secretion declined from weeks 6 to 14. No alteration was detected in either uridine diphosphate (UDP)-glucuronosyltransferase activity, cytochrome P-450 concentration, or hematological markers of hemolysis. This study shows that the migration of immature flukes in the course of ovine fasciolosis causes a cholestatic phenomenon responsible for changes in serum and biliary bilirubin levels.

Animals↗
PubMed1995

Seroprevalence of Fasciola hepatica infection in sheep in northwestern Spain.

To estimate the prevalence of Fasciola hepatica infection in sheep in the León province (northwestern Spain), we conducted a survey between October 1992 and May 1993. A total of 767 samples of feces and serum were collected from sheep over 1 year of age belonging to 152 flocks randomly selected from the 4 natural regions of León province. Samples were analyzed by a standard coprological sedimentation method and an indirect enzyme-linked immunosorbent assay (ELISA) using excretory-secretory products from F. hepatica as the antigen. The results showed the feasibility of using the indirect ELISA to facilitate the serodiagnosis of ovine fasciolosis in seroepidemiology studies (95% sensitivity and > 99% specificity). No serological cross-reaction with infection by the trematode Dicrocoelium dendriticum was found. Furthermore, a statistically significant association was demonstrated between the mean flock prevalence results as determined by ELISA (77.6%) and by coprological examination (23.7%; P < 0.001). Differences in the results obtained by the two diagnostic methods could have been due to fluctuations in the numbers of fluke eggs detected in feces and to the persistence of specific antibodies in serum after an efficacious fasciolicide treatment. The median number of F. hepatica eggs detected per gram of feces was 10 (range, 5-450 eggs/g feces). The geographical distribution of F. hepatica infection in León province was similar in all natural regions, probably due to the observation that meteorological conditions are not limiting for the maintenance of the parasite life cycle in any area of the province and to the abundance of irrigated areas together with the lack of planned control strategies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Cellular reactions in the small intestine of rats after infection with Fasciola hepatica.

Groups of five rats each were infected with metacercariae of Fasciola hepatica according to two experimental procedures. In the first experiment, they received 20 metacercariae 0, 1, 2 or 3 times at intervals of 4 weeks. In the second, both the inoculation dose and the interval between doses were varied. After the animals had been killed, the small intestine was prepared for histology and tissue sections were stained for the detection and quantification of mucosal mast cells (MMCs), eosinophils and goblet cells. The density of eosinophils and MMCs increased significantly with each reinfection in the first experiment; in the second, the MMC reaction reached a peak at 4 weeks post-infection (p.i.), whereas the eosinophils peaked at 4 and 17 weeks p.i. In addition, the reaction of these cells depended on the infectious dose. In both experiments, goblet cells reacted only weakly. These findings thus clearly reflect a considerable intestinal response against migrating juvenile F. hepatica. The pattern of these defence reactions in the small intestine suggests some similarities with the mechanisms of antibody-dependent cell-mediated cytotoxicity that have been shown to take place during Schistosoma mansoni reinfection.

Animals↗
PubMed1995

Comparative studies on the productivity of Fasciola gigantica and F. hepatica sporocysts in Lymnaea tomentosa that died after a cercarial shedding or without emission.

A histology study was performed on Fasciola gigantica- or F. hepatica-infected Lymnaea tomentosa that died after a cercarial shedding or without emission to compare the parasite productivity of each trematode. Degenerated rediae increased in number throughout the experiment. Their number rose rapidly after day 79 in snails that died after shedding in the F. gigantica group; they increased more slowly in snails that died without shedding. In the F. hepatica group the number rose after day 63 in the former snails and after day 79 in the latter. The contents of normal rediae evolved inversely. The number of morulae, for example, dropped rapidly after day 79 in the F. gigantica group. In the F. hepatica group it dropped after day 63 in snails that died after shedding and decreased after day 79 in the other dead snails. Free and degenerated cercariae were more numerous in snails that died without emission than in those that died at shedding. They rapidly increased in number after day 77. The numbers of rediae of F. gigantica were substantially greater than those of F. hepatica. In each group considered separately, it was likewise higher in snails that died without shedding than in those that died after the shedding of cercariae.

Animals↗
PubMed1982

Fasciola hepatica: plasma ascorbic acid, plasma iron and iron-binding capacity in experimentally infected sheep.

Six sheep were infected with about 520 Fasciola hepatica metacercariae. Plasma ascorbic acid decreased after infection attaining minimum values by week 10 and subsequently increased. Plasma iron concentrations were elevated during the first 6 weeks of exposure and then decreased till week 10; the levels approached pre-infection values at weeks 11-13 and again dropped. The iron-binding capacity rose during infection especially between weeks 13 and 19.

Animals↗
PubMed1978

Chaetogaster limnaei K von Baer 1872 on Lymnaea tomentosa: ingestion of Fasciola hepatica cercariae.

The fresh water mollusc, Lymnaea tomentosa, the intermediate host of the liver fluke is heavily infested under natural conditions with ectocommensal annelid, Chaetogaster limnaei. These annelids which destroy the larval stages of Fasciola hepatica have been observed in the laboratory. The association of C. limnaei with the snail intermediate host is of value in exploiting a control measure against economically important liver fluke disease.

Animals↗
PubMed1979

Attempts to immunise rats and mice against infection with fasciola hepatica using antigens prepared from taenia hydatigena.

Attempts were made to immunise rats and mice against infection with F. hepatica by oral dosing with T. hydatigena eggs, or by vaccination with various T. hydatigena antigen preparations. These antigens included extracts from T. hydatigena cysticerci and cyst fluid, and antigens collected during short-term (48 h) and long-term (14 days) in vitro cultivation of larvae. Immunity was assessed by the numbers of F. hepatica recovered from the challenge infection in rats, and the mortality rates of infected mice. None of the immunisation regimes with T. hydatigena antigens induced consistent, significant immunity. This was in contrast to the high level of immunity shown by rats dosed orally with F. hepatica metacercariae four weeks prior to challenge infection.

Animals↗