Lethal Fascioliasis in Capybaras ( Hydrochoerus hydrochaeris) in Brazil.

The liver fluke Fasciola hepatica (Trematoda: Fasciolidae) causes fascioliasis, which affects mostly domestic ruminants and humans worldwide. This parasite has an Old World origin and was introduced into the New World by European colonizers. Capybara ( Hydrochoerus hydrochaeris) is the largest living rodent species, with adults weighing over 60 kg. We report a fascioliasis outbreak caused by F. hepatica that reduced a capybara group from 21 to 2 animals within a 9-mo period. Animal infection and associated lesions were confirmed by postmortem examinations that revealed extensive liver damage associated with the presence of large number of adult and immature forms of F. hepatica. Both macroscopic and microscopic alterations in the liver were compatible with acute fascioliasis, which is characterized by a large parasite burden in the liver. Taxonomic identification of flukes collected from capybara livers were confirmed by molecular methods, which generated a mitochondrial NADH dehydrogenase I (NDI) gene partial sequence that was 100% identical to a F. hepatica NDI sequence from the United Kingdom. This is the first report of deleterious effects caused by F. hepatica in capybaras, highlighting the potential harm caused by this exotic parasite in the capybara.

The Battle of Worldviews: A Case Study of Liver Fluke Infection in Khon Kaen, Thailand.

Control efforts to reduce infection from the parasitic flatworm Opisthorchis viverrini have progressed through understanding the epidemiology of Opisthorchis viverrini, antiparasitic drug developments, technological innovations, health education promoting cooking of fish, and improved hygienic defecation. Yet the problem persists. The case study method was used to examine the fundamental cause of the liver fluke infection problem. Evidence shows that the liver fluke-infected population does not care about living a long life. For them, suffering and death are simply a part of life, and expected. Thus, the cause(s) leading to death is not important. They believe morally bad actions, and predetermined fate associated with kamma in Buddhism, play a big role whether or not one is infected with the liver fluke. Health interventions may be made more effective if they take into account the liver fluke-infected population's worldviews about ethics, morality, life, and death. We researchers should not feel concerned only about medically determined causes of death.

Adjuvant-enhanced antibody and cellular responses to inclusion bodies expressing FhSAP2 correlates with protection of mice to Fasciola hepatica.

Fasciola hepatica saposin-like protein-2 (FhSAP2) is a protein differentially expressed in various developmental stages of F. hepatica. Recombinant FhSAP2 has demonstrated the induction of partial protection in mice and rabbits when it is administered subcutaneously (SC) in Freund's adjuvant. Because FhSAP2 is overexpressed in bacteria in the form of inclusion bodies (IBs), we isolated IBs expressing FhSAP2 and tested their immunogenicity when administered SC in mice emulsified in two different adjuvants: QS-21 and Montanide TM ISA720. Animals received three injections containing 20 µg of protein two weeks apart and 4 weeks after the third injection, mice were infected with 10 F. hepatica metacercariae by oral route. The percentages of protection induced by FhSAP2-IBs were estimated to be between 60.0 and 62.5% when compared with adjuvant-vaccinated, infected controls. By determining the levels of IgG1 and IgG2a antibodies and IL-4 and IFNγ cytokines in the serum of experimental animals, it was found that both Th1 and Th2 immune responses were significantly increased in the FhSAP2-IBs vaccinated groups compared with the adjuvant-vaccinated, infected control groups. The adjuvant-vaccinated groups had significantly lower IgG1 to IgG2a ratios and lower IL-4 to IFNγ ratios than the FhSAP2-IBs vaccinated animals, which is indicative of higher levels of Th2 immune responses. Irrespective to the adjuvant used, animals vaccinated with FhSAP2-IBs exhibited significantly higher survival percentage and less liver damage than the adjuvant-control groups. This study suggests that FhSAP2 has potential as vaccine against F. hepatica and that the protection elicited by this molecule could be linked to a mechanism driven by the CD4-Th1 cells.

In vitro and in vivo studies for assessing the immune response and protection-inducing ability conferred by Fasciola hepatica-derived synthetic peptides containing B- and T-cell epitopes.

Fasciolosis is considered the most widespread trematode disease affecting grazing animals around the world; it is currently recognised by the World Health Organisation as an emergent human pathogen. Triclabendazole is still the most effective drug against this disease; however, resistant strains have appeared and developing an effective vaccine against this disease has increasingly become a priority. Several bioinformatics tools were here used for predicting B- and T-cell epitopes according to the available data for Fasciola hepatica protein amino acid sequences. BALB/c mice were immunised with the synthetic peptides by using the ADAD vaccination system and several immune response parameters were measured (antibody titres, cytokine levels, T-cell populations) to evaluate their ability to elicit an immune response. Based on the immunogenicity results so obtained, seven peptides were selected to assess their protection-inducing ability against experimental infection with F. hepatica metacercariae. Twenty-four B- or T-epitope-containing peptides were predicted and chemically synthesised. Immunisation of mice with peptides so-called B1, B2, B5, B6, T14, T15 and T16 induced high levels of total IgG, IgG1 and IgG2a (p<0.05) and a mixed Th1/Th2/Th17/Treg immune response, according to IFN-γ, IL-4, IL-17 and IL-10 levels, accompanied by increased CD62L+ T-cell populations. A high level of protection was obtained in mice vaccinated with peptides B2, B5, B6 and T15 formulated in the ADAD vaccination system with the AA0029 immunomodulator. The bioinformatics approach used in the present study led to the identification of seven peptides as vaccine candidates against the infection caused by Fasciola hepatica (a liver-fluke trematode). However, vaccine efficacy must be evaluated in other host species, including those having veterinary importance.

Livestock disease threats associated with intensification of pastoral dairy farming.

This paper provides an overview of the changes in the pasture-based dairy systems of New Zealand and Australia that may influence the health of cattle. There are relatively few available data that can be used to quantify the effects of increased intensification of milk production on the health of cattle. There is evidence that increased production increases the risk of mastitis and culling for udder health. Increased risks of mastitis with treatment with somatotropin support these findings; however, the risk of mastitis may decrease with increased milking frequency. Larger herds with greater stocking density should increase the risk for infectious disease, but evidence to support this contention is sparse. Very intensive grazing patterns associated with higher grass yields achieved using better cultivars and greater use of fertilisers favour nematode parasites. There is some evidence of anthelmintic resistance in both nematodes and liver fluke. Veterinarians will need to be aware of the potential for these to reduce the productivity of cattle. There have been benefits of improved nutrition on the efficiency of energy use for dairy production. Diseases such as bloat and ketosis appear to be of lower prevalence. It also appears that mineral nutrition of pasture-fed cattle is being better addressed, with gains in the control of milk fever, hypomagnesaemia and trace-element deficiencies. However, acidosis is a condition with a high point prevalence in pasture-based dairy systems where cows are fed supplements; one study in Australia found a point prevalence of approximately 11% of cows with acidosis. There is evidence from this study that the neutral detergent fibre (NDF) in pasture-based diets may need to be higher than 30% of the diet to maintain rumen stability. Laminitis and acidosis are different conditions with a similar pathogenesis, specifically highly fermentable diets. The prevalence of lameness was 28% in herds in Australia, suggesting that this condition must be a focus for preventive medical approaches, including the design of laneways, feed pads and dairies.

Oxidative-antioxidant status of Fasciola hepatica-infected rats supplemented with zinc. A mathematical model for zinc bioaccumulation and host growth.

The oxidative-antioxidant status of male Wistar rats infected or uninfected with Fasciola hepatica (Trematoda) and supplemented or unsupplemented with 2Gly.ZnCl(2).2H(2)O was tested through liver biomarkers. The oxidative marker was malondialdehyde concentration. The antioxidant markers were glutathione peroxidase activity and concentrations of zinc, selenium, vitamin A, vitamin C, and vitamin E. The animals were allocated into four groups. The experiment covered 8 weeks post infection. The gain in the host body weight and rats' mortality were also studied. A mathematical model was elaborated to describe the kinetics of concentrations of liver zinc. The kinetic parameters calculated reflect the peculiarities in zinc absorption in different conditions. Also, a model was proposed for the time course of host body weight. The model solutions were in good agreement with the experimental data. The supplementation of the rats with dietary Zn improved their antioxidant status. Increases by 9% in GPX activity, 6% in Vitamin A concentration, 3% in Vitamin C concentration, 35% in Vitamin E concentration, 17% in liver Zn concentration, and 11% in liver Se concentration, respectively, and a decrease by 30% in liver MDA concentration were recorded in the infected and supplemented towards infected and unsupplemented rats. Also, an increase by 6% in body weight in supplemented animals was established.

MUC1 and MUC5AC mucin expression in liver fluke-associated intrahepatic cholangiocarcinoma.

AIM: To investigate the expressions of MUC1 and MUC5AC in intrahepatic cholangiocarcinoma (ICC). Association of expressions of mucins MUC1 and MUC5AC with clinical findings, metastasis, and survival of the liver fluke-associated ICC patients was determined. METHODS: The expressions of MUC1 and MUC5AC mucins were examined by immunohistochemical staining in 87 cases of histologically-proven ICC. The expressions of mucins in relationship between clinicopathological significance and prognosis of the patients were evaluated. RESULTS: Fifty-two patients (60%) exhibited both MUC1 and MUC5AC expressions, whereas 31% expressed either MUC1 or MUC5AC, and 9% expressed neither. High MUC1 immunoreactivity displayed a significant correlation with tumor progression as reflected by vascular invasion (P<0.001), whereas high expression of MUC5AC significantly correlated with neural invasion (P = 0.022) and advanced ICC stage (P = 0.008). Patients with high expression of MUC1 had a significantly shorter survival (P = 0.0002). According to multivariate analyses, MUC1 reactivity (P = 0.026), histological grading and stage of tumor represented the least probability of survival. CONCLUSION: MUC1 is overexpressed in liver fluke-associated cholangiocarcinoma and relates to vascular invasion and poor prognosis, whereas MUC5AC mucin is neoexpressed and relates to neural invasion and advanced ICC stage. High MUC1 expression in tumor may be useful for predicting the poor outcome of ICC patients.

A first infection of Galba truncatula with Fasciola hepatica modifies the prevalence of a subsequent infection and cercarial production in the F1 generation.

Snails from two populations highly susceptible to Fasciola hepatica and their F1 generations were subjected to individual bimiracidial exposures to determine if changes noted in infection parameters were due to an effect imposed on the snail by the parasite, or to some other effect such as the food used for the snails. Apart from the higher survival of unexposed parents at day 30 post exposure (p.e.) and their higher shell heights at day 45 p.e., the differences between the survival rates of exposed parents, prevalences of infections, and shell sizes were not significant. In the F1 snails born to previously infected parents, the prevalences of F. hepatica infection and cercarial production were significantly lower than those noted for the F1 born to unexposed parents. The survival of these snails and their shell growth did not show any significant variation. The F1 snails born to previously exposed snails would have developed a partial resistance against F. hepatica and this process would probably be maximal in the first 2 weeks of larval development inside the snail.

Fasciola hepatica: the characteristics of experimental infections in Lymnaea truncatula subjected to miracidia differing in their mammalian origin.

Experimental infections of Lymaea truncatula, using two susceptible snail populations (Berneuil, or Migné, central France) and four isolates of Fasciola hepatica miracidia differing in their mammalian host of origin (cattle, nutrias, rabbits, or sheep), were performed under laboratory conditions to determine whether the host of origin had an effect on the daily production of cercariae. Snails were each subjected to bimiracidial exposures and were then reared under semi-natural conditions (a constant temperature of 20 degrees C and natural photoperiod). Significantly lower values were noted in the rabbit groups for survival rates at day 30 post-exposure, as well as for prevalences of infection, snail growth. duration of shedding period, and the total numbers of cercariae these snails shed. The total number of cercariae shed by both nutria groups was significantly higher than those recorded in the six other infected groups. In the cattle, rabbit, and sheep (Berneuil only) groups, the peaks in the daily distribution of cercariae occurred between day 2 and day 4 after the first shedding, and the number of cercaria-shedding snails decreased with increasing number of shedding waves. In contrast, in the three other groups, the peaks were only observed between days 20 and 45. Snails shedding their cercariae during nine or more waves were numerous in these last groups. No infradian-type rhythm in the daily distribution of cercarial numbers over the shedding period was noted for any snail group. The highest production of F. hepatica cercariae in both nutria groups would be a consequence of a higher success rate of miracidia when they infected an allopatric population of snails. The absence of an infradian-type rhythm in the distribution of daily cercarial numbers in the eight groups suggests that this rhythm, if it occurs, would only be influenced by temperature and thus be limited to periods with optimal conditions for cercarial shedding.

Fasciola hepatica: characteristics of infection in Lymnaea truncatula in relation to the number of miracidia at exposure.

Experimental infections of Lymnaea truncatula by Fasciola hepatica were carried out in three snail populations to determine whether the number of miracidia used for each snail at exposure (1, 2, 5, 10, or 20 per snail) had any influence on the characteristics of Fasciola infection and metacercarial production. The number of miracidia had a significant influence on snail survival at day 30 postexposure and the frequency of infected L. truncatula that died without shedding (NCS snails). The frequency of NCS snails, the growth of cercaria-shedding snails throughout the experiment, the time between exposure and the first cercarial shedding, the duration of shedding, and the number of metacercariae were independent of the number of miracidia used for each snail. The highest metacercaria productivity for each miracidium was found in single-miracidium infections. Single-miracidium infections were the most effective, as the mean number of cercariae was the same as in other groups, whereas their survival rate was much higher.

Fasciola gigantica and F hepatica: a comparative study of some characteristics of Fasciola infection in Lymnaea truncatula infected by either of the two trematodes.

Experimental infections were carried out using three Lymnaea truncatula populations and two Fasciola species in order to determine the trematode influence on six parameters of snail infection by either of the two trematodes. All experiments were performed using snails 4 mm long, two miracidia for each L truncatula, and a constant temperature of 20 degrees C. No significant influence of trematode species was detected in the following parameters: snail survival at day 30, the life span of infected snails (from miracidial exposure to snail death), the increase in shell length throughout the experiment, the duration of the patent period and the number of cercariae shed by infected snails. The frequency of cercaria-shedding snails was closely correlated with the particular L truncatula population and trematode species. A similar finding in two populations was also noted for the frequencies found in the infected snails who died without emission. The prepatent period had a longer duration in the Fasciola gigantica-infected groups. The percentages of floating cysts were greater in the Fasciola gigantica groups than in the Fasciola hepatica groups.

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.

Financial losses caused by ovine fasciolosis in the Ethiopian highlands.

An estimate of the economic loss due to ovine fasciolosis in the Ethiopian highlands was made based on available data on mortality, weight loss, reduced reproductive efficiency and liver condemnation at slaughter. The economic effects of fasciolosis were identified and models for estimating the financial loss presented. Ovine fasciolosis losses were estimated at 48.4 million Ethiopian Birr per year of which 46.5, 48.8 and 4.7% were due to mortality, productivity (weight loss and reproductive wastage) and liver condemnation, respectively. These losses can be reduced substantially by fasciolosis control programmes that may include the use of anthelmintics, grazing management and nutritional supplementation.

Causes of mortality in impala (Aepyceros melampus) on 20 game farms in Zimbabwe.

The most common cause of death in impala (Aepyceros melampus) herds on 20 game farms in Zimbabwe was stress or physical injury during capture. Acute fascioliasis due to Fasciola gigantica was identified as the main disease problem associated with smaller game farms and where impala had been recently introduced. Losses associated with ticks and tick-borne diseases were rare. Impala in Zimbabwe are maintained in a healthy condition on game farms where they are given supplementary feed during the dry winter.

Infectivity and pathogenicity of Fasciola gigantica in West African dwarf sheep and goats.

The infectivity and pathogenicity of Fasciola gigantica for sheep and goats were investigated in animals infected with single doses of between 200 and 2,000 metacercariae. Acute fascioliasis occurred in sheep infected with 1,000 to 2,000 cysts in which 10 to 17% of the cysts became established. The infected animals died 80 to 90 days after infection. In goats given the same infective doses death from acute fascioliasis occurred earlier (70 to 83 days after infection) and 12 to 38% of cysts became established. Subacute fascioliasis could occur in both hosts with an infective dose of 200 cysts, the animals surviving for more than 100 days. It therefore appears that F. gigantica is more infective for goats and that the disease was more severe in this host than in sheep.

Density-dependent mechanisms in the regulation of Fasciola hepatica populations in sheep.

Populations of Fasciola hepatica infecting sheep are regulated by at least 3 density-dependent processes. Parasite deaths due to parasite-induced primary host mortality, fluke fecundity and asexual multiplication in the intermediate snail host, Lymnaea truncatula, vary according to the intensity of infection. Empirical and theoretical evidence is used to assess the extent to which each of these processes in turn affects parasite population numbers.