Fasciola hepatica

Fasciolid flukes are among the largest and best known digenetic trematodes and have considerable historical and veterinary significance. Fasciola hepatica is commonly implicated in causing disease in humans. The origins, patterns of diversification, and biogeography of fasciolids are all ...

Sixteen human cases of Fasciola hepatica infection are described. The liver was involved in 13 cases, the gall bladder in 9 cases and the stomach in 2 cases. Lesions containing parasitic remnants or fluke eggs were rarely seen. Surface scarring of the liver, scar tracks and granulomas within organs were the most characteristic changes seen and were the most useful for the histopathological diagnosis of the disease. The associated liver, bile and gastric lesions are briefly discussed.

Two cases of hepatic fascioliasis due to Fasciola hepatica were retrieved from our surgical-pathology file since the hospital's foundation in 1969 up to 2005. The diagnosis of hepatic fascioliasis was based on detection of one live fluke in a large cystic lesion in the lobectomized liver specimen in one case and of deposited eggs in the large liver specimen obtained from open biopsy in the other Hepatic fascioliasis is rather rare and almost worldwide in distribution including Thailand. The diagnosis should be considered in the patient from endemic areas consisting of the northern, northeastern and upper-central regions of the country, with a history of ingesting fresh water plants or drinking untreated water and having fever right-upper-quadrant pain or intrahepatic cystic lesion(s) together with absolute peripheral blood eosinophilia.

Fasciola hepatica is a trematode commonly known as sheep liver fluke causing Fascioliasis or sheep liver rot. Transmission of infection to human is through ingestion of raw infected water plants. Fasciola hepatica is found worldwide, particularly in areas where cattle and sheep are raised. Humans serves as accidental host whereas sheep is the natural host for the completion of its life cycle.

Fascioliasis, caused by liver fluke species of the genus Fasciola, has always been well recognized because of its high veterinary impact but it has been among the most neglected diseases for decades with regard to human infection. However, the increasing importance of human fascioliasis worldwide has re-launched interest in fascioliasis. From the 1990s, many new concepts have been developed regarding human fascioliasis and these have furnished a new baseline for the human disease that is very different to a simple extrapolation from fascioliasis in livestock. Studies have shown that human fascioliasis presents marked heterogeneity, including different epidemiological situations and transmission patterns in different endemic areas. This heterogeneity, added to the present emergence/re-emergence of the disease both in humans and animals in many regions, confirms a worrying global scenario. The huge negative impact of fascioliasis on human communities demands rapid action. When analyzi...

The aim of this study was to compare the efficacy of triclabendazole (TCBZ) and nitroxynil against a TCBZ-resistant Fasciola hepatica strain in a naturally infected sheep flock. The efficacies were measured by the faecal egg count reduction test. The level of F. hepatica antigens was tested in faeces; and haematological indices such as total proteins (TP), albumin, hepatic enzymes and total IgG were also studied. The results confirmed the resistance of F. hepatica against TCBZ in the flock with an efficacy during the first month post-treatment between 59.4% and 73.8%. In the nitroxynil group, the efficacy during the same period ranged between 81.3% and 86%, likely because the efficacy of this drug against 7- to 9-week-old immature stages is only 50–90%. Anemia was showed in all groups and white blood cells were always higher than the reference range. The values of TP and albumin were within normal range in most of the sheep, and an increase in hepatic enzymes confirmed the liver damage. Regarding total IgG, some negative correlations were found with egg excretion, and in relation to the level of antigens in faeces, these ones decreased immediately after treatment. We conclude that nitroxynil could be an alternative in case of TCBZ resistance.

El presente estudio hace una comparación entre los resultados de la técnica de Dennis para diagnóstico de Fasciolosis bovina, frente a hallazgos post mortem, en hígados de bovinos faenados en la empresa Matadero de Tunja. Es un estudio experimental descriptivo, por cuanto expone los hallazgos en matadero frente a los arrojados por el método de Dennis. La población total de bovinos adultos fue de 2800, de los cuales se tomó una muestra de 139 animales. El muestreo se llevó a cabo durante el mes de febrero del año 2009. Los resultados indican que la técnica de Dennis no es lo suficientemente sensible para el diagnóstico de Fasciola hepática, por lo que se debe evaluar su uso rutinario.La técnica coprológica se fundamenta en el principio de sedimentación delos huevos, por lo tanto depende la salida de éstos en la materia fecal, lo que la hace poco efectiva para la detección del parásito. La razón de este estudiose sustenta en que la enfermedad se encuentra ampliamente distribuida en la región y en el país. Su diagnóstico se realiza rutinariamente mediante técnicas coprológicas aplicadas a los animales en los que se sospecha la enfermedad.

A study was carried out to determine the prevalence and the species of liver flukes in indigenous adult cattle, to compare the diagnostic efficiency of fecal and post mortem examination and to assess the economic significance of bovine fasciolosis due to liver condemnation in the abattoir. Of the 406 livers and fecal samples examined, 57 (14.0%) and 20 (4.9%) were positive for fasciolosis. The most common liver fluke species affecting the cattle was Fasciola gigantica, 9.1% of cattle were infected with F. gigantica while, Fasciola. hepatica, mixed infections and unidentified or immature forms of Fasciola spp. were present in 3.2 %, 0.7% and 1 % of cattle, respectively. A retrospective abattoir survey revealed that the prevalence of fasciolosis was 12.7%. The prevalence of fasciolosis recorded in this study was lower than that reported by other researchers in this country. There was a strong relationship between fecal examination and postmortem findings of liver lesions, (K = 0.23) but under local conditions, postmortem examination was considered a better diagnostic tool for fasciolosis. Fasciolosis is of significant economic importance as the resultant liver condemnations caused an average loss of 4000 USD per annum. Hence, this disease deserves serious attention by the various stakeholders in order to promote the beef industry in the study area in particular and in the country in general.

Experimental infections of Galba truncatula with Fasciola gigantica or F. hepatica were carried out under laboratory conditions (20°C) to determine the characteristics of rediae of both species via their morphometry and to find reliable measurements that might be efficiently used to discriminate between the rediae of both species of Fasciola. These results were compared to those of another snail: Radix natalensis, infected with either F. gigantica or F. hepatica under the same protocol. At day 28 post-exposure, abortive infections with F. hepatica were found in a group of R. natalensis. By contrast, live rediae were observed in the other three groups. The group of infected snails and the redial category significantly influenced the mean values of the seven measurements studied and those of three indices. Using the PSLD Fisher test, it was found that the index, distance from the anterior end of the body to the collar/length of the body, was an efficient means of distinguishing the rediae of F. hepatica from those of F. gigantica [second-appearing mother rediae (R1b) of the first generation, 0.14 instead of 0.22; daughter rediae (R2a) produced by the first mother rediae, 0.19 instead of 0.24]. Another index, distance from the anterior end of the body to the collar/diameter of the collar, could also be used to discriminate between rediae (R1b, 0.80 for F. hepatica instead of 1.09 for F. gigantica; R2a, 0.90 instead of 1.26, respectively). Compared to measurements recorded for the rediae of F. hepatica, rediae of F. gigantica can be characterized by the following measurements: the diameter of the pharyngeal lumen and the distance from the anterior end of the body to the collar for larvae developed in R. natalensis, and the length of the body and the distance from the posterior end of the body to lateral projections for those found in G. truncatula. The species of snail host and, consequently, its growth, as well as the species of Fasciola, had a significant influence on the morphometric characters of the redial stage.

We described the transmission dynamics of Fasciola hepatica at its southern distribution range. Studies of prevalence and egg output in cattle and population dynamics and infection in snails were performed in a farm in the Andean Patagonian valleys, Argentina, between December 1998 and February 2002. Snail surveys were conducted from spring to autumn. Infection was diagnosed coprologically in the whole herd at the beginning and end of the study, and in a cohort of heifers at the beginning and end of 2001. A twice-a-year anthelmintic treatment was implemented in 1999. The relationship of the variables mentioned above with temperature and rainfall was determined. Lymnaea viatrix showed a life-span of about 15 months and an annual pattern of population dynamics. Specimens were frequently found in temporary environments and lagoons, and rarely in streams. Snail abundance and soil-water availability were directly related in temporary environments and inversely related in lagoons. Overall prevalence in L. viatrix was 0.67% (range: 0.9–14%) and infection was detected in summer and autumn. At the beginning of the study, calves were the least infected age group (15%). Prevalences and median egg counts in grazing animals were similar at the beginning (heifers: 81%, 3.3 epg; cows: 60%, 1.3 epg) and end of the study (heifers and cows: around 51%, 1 epg). Likewise, the prevalence in the cohort of heifers remained similar (around 40%) between surveys. Transmission to cattle was highly effective despite of the short activity period and the low infection rate of snails, and the regular anthelminthic treatment. There would be two seasonal transmission peaks, one in summer–autumn, when infected snails were present, and the other in early spring due to overwintering metacercariae. Some recommendations based on the climatic conditions of the region are provided to minimize snail infection and ultimately to reduce the incidence of fasciolosis in cattle.

Fasciolosis caused by Fasciola spp. (Platyhelminthes: Trematoda: Digenea) is considered the most important helminth infection of ruminants in tropical countries, causing considerable socioeconomic problems. In the present study, samples identified morphologically as Fasciola hepatica from sheep and cattle from different geographical locations of Tunisia and Algeria were genetically characterised by sequences of the first (ITS-1), the 5.8S and second (ITS-2) Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA (rDNA) and mitochondrial Cytochrome c Oxidase subunit I (COI) gene. Comparison of the ITS and COI sequences of the North African samples with sequences of Fasciola spp. from GenBank confirmed that all samples from Tunisia and Algeria samples belong to a single species, namely F. hepatica. Several specimens from Tunisia and Algeria showed a substitution C/T in position 859 in the ITS-2 sequences, previously reported from Spain, suggesting that the above mentioned variant may have a common origin and spread recently throughout the three countries because of movement of infected animals. This is the first molecular characterization of F. hepatica in North Africa which provides a foundation for further studies on Fasciola spp. in Tunisia and Algeria.

To investigate the seroprevalence of fasciolosis and the possible causes of differences between rural and city center. We undertook a multi-stage sampling analysis of data from Isparta, Turkey, between March and June 2004. Four hundred and fifteen individuals participants from Isparta center and 171 from Asagi Gokdere village were included in the study. Fasciola hepatica (F. hepatica) specific antibodies were analyzed using excretory-secretory (ES)-enzyme-linked immunosorbent assay (ELISA) method. Fasciola hepatica antibodies were detected as positive in 10 (2.4%) of 415 people whose sera were collected from the city center and 16 (9.3%) of 171 people from Asagi Gokdere village. The positivity rates between village and city center were found statistically significant. A statistical difference was noted for fasciolosis positivity between individuals who have ingested water cress and who have not. Fasciolosis was not detected in the individuals who used to wash vegetables with water c...

The control of fasciolosis, as that of other vectorborne diseases, must be related to the control of the lymnaeid
snails, the intermediate hosts of the parasite. Thus, an accurate
epidemiological surveillance of the transmission foci where
the infected mollusks occur is essential. For this purpose,
immunoassays could be a useful tool. However, information
regarding specific proteins of intramolluscan larvae and previous studies concerning monoclonal antibody generation
against asexual stages of trematodes are scarce. Therefore,
we explored the antigenic features of intramolluscan rediae
of Fasciola hepatica to evaluate three antigenic preparations
in order to use the most promising one for developing specific
monoclonal antibodies. Mouse antiserum was generated
against each antigen for assessing the polyclonal antibody
response against the crude extract of rediae and the crossreactivity against lymnaeids. The specific C-terminal of
F. hepatica cytochrome c oxidase subunit I (first antigen),
selected by in silico analyses, might not be the appropriate
target for immunoassay detection of infected snails, due to its
low representation in the total extract of rediae. The majoritarian mixture of low-molecular-weight proteins (<30 kDa) from the rediae homogenate (second antigen) revealed a significant cross-reactivity with lymnaeids. Evidence of the existence of mimetic immunogenic epitopes in this fraction of
F. hepatica rediae was achieved. High immunogenicity of the
crude extract of rediae (third antigen), mainly related to parasite’s specific epitopes, was regarded. Therefore, the rediae
homogenate is stated as the most promising antigen from
those evaluated, for monoclonal antibody development with
potentialities for detecting F. hepatica-infected snails.

We report the first finding of Lymnaea cousini naturally infected with Fasciola hepatica in Ecuador. A sample of 70 snails was collected in April 2005 from a wetland located in a valley at approximately 3000 m a.s.l., near the locality of Machachi, Pichincha Province. The prevalence of natural infection in L. cousini was 31.43%, which is the highest value ever recorded for naturally infected lymnaeid species.