Immunodiagnosis of human fascioliasis by an enzyme-linked immunosorbent assay (ELISA) and a micro-ELISA

Serological diagnosis of fasciolosis (Fasciola hepatica) in humans, cattle, and sheep: a meta-analysis

Fasciola hepatica can cause problems in both animals and humans. Fasciolosis can be diagnosed through the indirect ELISA immunodiagnostic test. Serological diagnosis of Fasciola is based on recombinant antigens secreted by this worm. We used PubMed and Google Scholar databases to review the published literature on 'antigens with immunogenic potential' used in serological tests to identify antibodies against F. hepatica in humans, cattle, and sheep. Studies that investigated diagnostic tests with common reference standards were included in the sensitivity and/or specificity bivariate meta-analysis. In the quality and susceptibility to bias analysis of the 33 included studies, 26 fulfilled at least six (75%) of the eight QUADAS criteria and were considered good-quality papers. We found that most of the studies used native excretory-secretory antigens and recombinant cathepsin in ELISA tests for serological diagnosis of fascioliasis in humans, cattle, and sheep. The meta-analysis revealed that all antigens demonstrated good accuracy. The best results in terms of sensitivity [0.931-2.5% confidence interval (CI) and 0.985-97.5% CI] and specificity (0.959-2.5% CI and 0.997-97.5% CI) were found in human FhES. FhrCL-1, FhES, and FhrSAP-2 antigens gave the best results for the serum diagnosis of human and animal fasciolosis.

Hepatic mass caused by Fasciola hepatica: A case report

Introduction

Fascioliasis is a zoonotic infestation which presents with a wide spectrum of clinical pictures. However, it may often be overlooked, especially in the acute phase, because of uncertain symptoms. Fasciola hepatica can have an initial presentation similar to malignant liver mass or complex hepatic cyst. Here, we report a case of a hepatic mass caused by fasciola hepatica.

Case presentation

A 48-year-old woman came with chief complaints of epigastric and right hypochondrial discomfort associated with nausea and vomiting. Ultrasonography (USG) showed a heterochronic lesion in the segment VIII of the liver with few cystic lesions. CECT abdomen and pelvic gave impression of ill-defined irregular hypodense lesions in the right lobe of the liver with progressive enhancing peripheral and central cystic areas suggestive parasitic liver infestation likely echinococcus alveolaris. Right hepatectomy was done and the patient was discharged without any complications.

Discussion

Fascioliasis is uncommon in developed countries but more commonly seen in developing countries. The identification of fasciola hepatica eggs in the stool is a standard method for the diagnosis of fascioliasis. Fascioliasis may cause a wide variety of clinical signs ranging from asymptomatic infection to severe liver cirrhosis. Surgery for complex hydatid cysts of the liver is potentially burdened by serious complications. Technique of choice for surgical management remains inconclusive.

Conclusion

Fasciola hepatica infection can mimic a malignant liver mass or a complex hepatic cyst because of its uncertain presentation. The disease can be prevented with public education and environmental precautions.

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Fascioliasis is a zoonotic infestation which presents with a wide spectrum of clinical pictures

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Fasciola hepatica infection can mimic a malignant liver mass or a complex hepatic cyst

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The disease can be prevented with public education and environmental precautions.

Construction of a multiepitope vaccine candidate against Fasciola hepatica: an in silico design using various immunogenic excretory/secretory antigens

BACKGROUND

Fasciola hepatica is an important pathogen that causes liver fluke disease in definitive hosts such as livestock animals and humans. Various excretory/secretory products have been used in serological diagnosis and vaccination studies targeting fasciolosis. There are no commercial vaccines against fasciolosis yet. Bioinformatic analysis based on computational methods have lower cost and provide faster output compared to conventional vaccine antigen discovery techniques. The aim of this study was to predict B- and T-cell specific epitopes of four excretory/secretory antigens (Kunitz-type serine protease inhibitor, cathepsin L1, helminth defense molecule, and glutathione S-transferase) of Fasciola hepatica and to construct a multiepitope vaccine candidate against fasciolosis.

METHODS AND RESULTS

Initially, nonallergic and the highest antigenic B- and T- cell epitopes were selected and then, physico-chemical parameters, secondary and tertiary structures of designed multiepitope vaccine candidate were predicted. Tertiary structure was refined and validated using online bioinformatic tools. Linear and discontinuous B-cell epitopes and disulfide bonds were determined. Finally, molecular docking analysis for MHC-I and MHC-II receptors was performed.

CONCLUSION

This multi-epitope vaccine candidate antigen, with high immunological properties, can be considered as a promising vaccine candidate for animal experiments and wet lab studies.

Use of the PCR in a Combined Methodological Approach for the Study of Human Fascioliasis in an Endemic Area

PURPOSE

Fascioliasis is a worldwide distributed trematodiasis considered a neglected disease. Diagnosis in humans has been traditionally based on parasitological and immunological techniques. Recently we reported the use of the PCR in stool samples for the individual diagnosis. The purpose of this study was to evaluate human fascioliasis by a combination of diagnostic methods in an area where the disease is highly endemic in animals.

METHODS

We studied all the inhabitants (N = 240) of Tatón village, Argentina, by Fasciola hepatica rproCL1-ELISA. Among them, we continued the study with 13 cases that had at least two positive serological tests, who performed a questionnaire, physical examination, abdominal ultrasonography, and collection of blood and faeces. Blood/serum samples were used for Fh rproCL1-ELISA and liver function tests. Faeces were used for parasitological analysis and PCR of a repetitive fragment of Fasciola sp.

RESULTS

Among the 13 patients, 9 presented symptoms of biliary colic. All patients repeated positive serology. F. hepatica eggs were not detected. PCR was positive in 11 cases.

CONCLUSION

This is the first report employing an approach based on the combination of methods for the evaluation of human fascioliasis in an endemic area, which includes molecular tools with a high value in detecting low infections.

Recent Developments in Recombinant Proteins for Diagnosis of Human Fascioliasis

Fascioliasis is an important neglected tropical disease that causes severe injury to the bile ducts and liver. Therefore, a rapid and accurate method for detection of Fasciola hepatica infection plays a vital role in early treatment. Currently, the diagnosis of fascioliasis is mainly conducted via serological tests using the excretory/secretory (E/S) products, which might cross-react with antigens from other helminth parasitic diseases. Hence, the development of serodiagnosis test using recombinant antigens may contribute to differentiate fascioliasis from other helminth infections. In the past 20 years, many attempts have been made to exert different F. hepatica recombinant antigens to obtain a well-established standard assay with high accuracy. In this review, we address recent studies that refer to the development of serodiagnosis tests for diagnosis of human fascioliasis based on the candidate recombinant antigens produced by different approaches. Meanwhile, in the present review, some main factors have been highlighted to improve the accuracy of diagnostic tests such as the effect of refolding methods to recover antigens' tertiary structure as well as applying a mixture of recombinant antigens with the highest sensitivity and specificity to improve the accuracy of diagnostic tests.

Development and evaluation of a colloidal gold immunochromatographic assay based on recombinant protein CatL1D for serodiagnosis of sheep fasciolosis

Fasciolosis is a zoonotic parasitic disease that seriously endangers the development of animal husbandry and human health. In order to develop a rapid serological diagnostic method for fasciolosis in ruminants, the CatL1D and CatB4 genes of Fasciola hepatica were amplified by reverse transcription polymerase chain reaction (PCR) and cloned, respectively, and then the CatL-B fusion gene (MeCatL-B) was constructed by gene splicing by overlap extension PCR technique. The recombinant rCatL1D, rCatB4 and rMeCatL-B proteins were then prepared by prokaryotic expression, respectively, and the recombinant protein with high specificity and sensitivity was screened via indirect enzyme-linked immunosorbent assay. Using the selected recombinant protein rCatL1D as a diagnostic antigen, we developed a colloidal gold immunochromatographic assay (CGIA) for detecting F. hepatica-specific antibodies, and 426 serum samples of slaughtered sheep were used to evaluate the sensitivity and specificity of F. hepatica CGIA assay. The results showed that the sensitivity and specificity of rCatL1D protein (100%, 96.67%) were higher than those of rCatB4 (94.29%, 80%) and rMeCatL-B (91.43%, 90%). Compared with the gold standard post-mortem inspection, the specificity and sensitivity of the CGIA method was 100% and 97%, respectively, and the consistency rate between these two methods was 99.3%. These results confirmed that the CGIA method based on rCatL1D protein could be a promising approach for rapid diagnosis of sheep fasciolosis because of its high sensitivity and specificity.

Assessment of Fasciola hepatica glutathione S-transferase as an antigen for serodiagnosis of human chronic fascioliasis

Due to the unsatisfactory performance of parasitological diagnosis of human fascioliasis; the use of immunodiagnosis based on the detection of anti-Fasciola antibodies is traditionally used as a diagnostic alternative using total or purified parasite excretory-secretory products (ESPs). Glutathione S-transferase (GST) protein, one of the F. hepatica ESP components, possesses well-known roles in the detoxification of xenobiotic and endogenously derived toxins within the host bile environment. GST has shown to be a good target for vaccine or drug development against fascioliasis. The current study aimed to evaluate the potential of GST protein purified from a soluble crude extract of adult flukes as an antigen for serodiagnosis of chronic human fascioliasis by indirect ELISA. The study included a panel of 116 serum samples collected from individuals with confirmed fascioliasis, individuals carrying heterologous parasitic infections and healthy subjects. The parasitological examination was used as gold standard and a previously optimized ESP-ELISA was used to compare the performance of the GST-ELISA method. Results demonstrated that GST-ELISA is 94.3% sensitive, 80.2% specific and exhibits a moderate positive correlation (r = 0.555) and substantial agreement (k = 0.786) with the results obtained with the ESP-ELISA method. Moreover, because no sera from patients with early F. hepatica infection were available, GST-ELISA was then tested with sera from rabbits experimentally infected with F. hepatica metacercariae. The assay was able to detect anti-Fasciola antibodies as early as the 3^rd week of infection (p < 0.0001) with peaks at 4^th and 10^th week post-infection.

Comparison of recombinant cathepsins L1, L2, and L5 as ELISA targets for serodiagnosis of bovine and ovine fascioliasis

Infections caused by Fasciola hepatica are of great importance in the veterinary field, as they cause important economic losses to livestock producers. Serodiagnostic methods, typically ELISA (with either native or recombinant antigens), are often used for early diagnosis. The use of native antigens, as in the MM3-SERO ELISA (commercialized as BIO K 211, BIO-X Diagnostics), continues to be beneficial in terms of sensitivity and specificity; however, there is interest in developing ELISA tests based on recombinant antigens to avoid the need to culture parasites. Of the antigens secreted by adult flukes, recombinant procathepsin L1 (rFhpCL1) is the most commonly tested in ELISA to date. However, although adult flukes produce three different clades of CLs (FhCL1, FhCL2, and FhCL5), to our knowledge, the diagnostic value of recombinant FhCL2 and FhCL5 has not yet been investigated. In the present study, we developed and tested three indirect ELISAs using rFhpCL1, rFhpCL2, and rFhpCL5 and evaluated their recognition by sera from sheep and cattle naturally infected with F. hepatica. Although the overall antibody response to these three rFhpCLs was similar, some animals displayed preferential recognition for particular rFhpCLs. Moreover, for cattle sera, the highest sensitivity was obtained using rFhpCL2 (97%), being equal for both rFhpCL1 and rFhpCL5 (87.9%), after adjusting cut-offs for maximum specificity. By contrast, for sheep sera, the sensitivity was 100% for the three rFhpCLs. Finally, the presence of truncated and/or partially unfolded molecules in antigen preparations is postulated as a possible source of cross-reactivity.

Fasciola hepatica ESPs Could Indistinctly Activate or Block Multiple Toll-Like Receptors in a Human Monocyte Cell Line

Fasciola hepatica is a parasitic helminth that induces Th2/Treg responses in its mammalian host. Some reports have suggested that ESPs achieve these polarized immune responses by delaying the activation of dendritic cells and macrophages during the early stages of innate immunity, a process that is mediated by TLR4. The present study aimed to investigate whether TLRs other than TLR4 could also be targeted by F. hepatica ESPs. To achieve this aim a screening system was optimized using THP1-Blue CD14 cells. ESPs were first separated based on their molecular weight and according their net charge by ion exchange chromatography (IEC). Results demonstrated that F. hepatica ESPs mainly cathepsin, serpin and endopin are capable of activating TLR2, TLR4, TLR8 and likely also TLR5 and TLR6. In contrast, fatty acid binding protein strongly suppressed the stimulation induced by various TLR-ligands. Further studies are needed to understand how these apparent contradictory effects of molecules of the same protein mix complement each other in the context of an active infection resulting in the polarized Th2-immune response that characterize F. hepatica infections.

Evaluation of anti-Cathepsin L1: a more reliable method for serodiagnosis of human fasciolosis

BACKGROUND

Coprological examinations are commonly used for diagnosis of fasciolosis. However, these methods are not useful during the acute phase of the infection and also show poor sensitivity during its chronic phase. In this study we compared the immunoreactivity of the native and recombinant forms of Fasciola hepatica excretory/secretory antigens and determined the most appropriate one for development of F. hepatica-specific immunoassays.

METHODS

The coding sequences of previously-determined immunogenic proteins including cathepsin L1 (CL1), fatty acid binding protein (FABP) and glutathione-S-transferase (GST) were cloned and expressed in E. coli BL-21 cells. Native forms of FABP and GST were also purified. We evaluated the immunoreactivity of the native and recombinant proteins by ELISA using sera from 40 healthy individuals, 15 fasciolosis patients, and 57 patients with other infectious diseases.

RESULTS

All of the studied proteins showed high sensitivity and specificity for F. hepatica serodiagnosis. However, CL1 was more sensitive and specific (100%) than the others for the detection of F. hepatica-specific antibodies. Notably, both FABP and GST showed significant cross-reactivity with hydatidosis patients' sera while CL1 did not.

CONCLUSIONS

Cathepsin L1 has acceptable sensitivity and specificity for serodiagnosis of F. hepatica and its application could be advantageous in immunoassay development.

Therapeutic Endoscopic Retrograde Cholangiopancreatography for the Treatment of Fasciola hepatica Presenting as Biliary Obstruction

Human infection with the Fasciola hepatica liver fluke is a rare cause of biliary obstruction, especially within the United States. Humans can become accidental hosts of this parasite by ingesting contaminated drinking water or plants. Symptoms during the acute phase include fever, right upper quadrant pain, eosinophilia, and hepatomegaly. During the chronic stage of infection, the parasite may remain asymptomatic for many years. This article presents a case of biliary obstruction due to Fasciola hepatica that was diagnosed and treated successfully with endoscopic retrograde cholangiopancreatography.

Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transmission pattern

BACKGROUND

In South America, fascioliasis stands out due to the human endemic areas in many countries. In Argentina, human endemic areas have recently been detected. Lymnaeid vectors were studied in two human endemic localities of Catamarca province: Locality A beside Taton and Rio Grande villages; Locality B close to Recreo town.

METHODS

Lymnaeids were characterised by the complete sequences of rDNA ITS-2 and ITS-1 and fragments of the mtDNA 16S and cox1. Shell morphometry was studied with the aid of a computer image analysis system. Climate analyses were made by nearest neighbour interpolation from FAO data. Koeppen & Budyko climate classifications were used. De Martonne aridity index and Gorczynski continentality index were obtained. Lymnaeid distribution was assessed in environmental studies.

RESULTS

DNA sequences demonstrated the presence of Lymnaea neotropica and L. viator in Locality A and of L. neotropica in Locality B. Two and four new haplotypes were found in L. neotropica and L. viator, respectively. For interspecific differentiation, ITS-1 and 16S showed the highest and lowest resolution, respectively. For intraspecific analyses, cox1 was the best marker and ITS-1 the worst. Shell intraspecific variability overlapped in both species, except maximum length which was greater in L. viator. The desertic-arid conditions surrounding Locality A, the semiaridity-aridity surrounding Locality B, and the very low yearly precipitation in both localities, are very different from the typical fascioliasis transmission foci. Lymnaeids are confined to lateral river side floodings and small man-made irrigation systems. Water availability only depends on the rivers flowing from neighbouring mountains. All disease transmission factors are concentrated in small areas where humans and animals go for water supply, vegetable cultures and livestock farming.

CONCLUSIONS

The unusually high number of DNA haplotypes and the extreme climate unsuitable for F. hepatica and lymnaeid development, demonstrate that the transmission foci are isolated. Seasonal transmission may depend on the timely overlap of appropriate temperature and river water availability. Lymnaeids and F. hepatica have probably reached these localities by livestock introduction. DNA differences regarding other populations of L. neotropica and L. viator in Argentina suggest an introduction independent from the spreading movements which allowed these two lymnaeids to expand throughout the country.

Techniques for the diagnosis of Fasciola infections in animals: room for improvement

The common liver fluke, Fasciola hepatica, causes fascioliasis, a significant disease in mammals, including livestock, wildlife and humans, with a major socioeconomic impact worldwide. In spite of its impact, and some advances towards the development of vaccines and new therapeutic agents, limited attention has been paid to the need for practical and reliable methods for the diagnosis of infection or disease. Accurate diagnosis is central to effective control, particularly given an emerging problem with drug resistance in F. hepatica. Traditional coprological techniques have been widely used, but are often unreliable. Although there have been some advances in establishing immunologic techniques, these tools can suffer from a lack of diagnostic specificity and/or sensitivity. Nonetheless, antigen detection tests seem to have considerable potential, but have not yet been adequately evaluated in the field. Moreover, advanced nucleic acid-based methods appear to offer the most promise for the diagnosis of current infection. This chapter (i) provides a brief account of the biology and significance of F. hepatica/fascioliasis, (ii) describes key techniques currently in use, (iii) compares their advantages/disadvantages and (iv) reviews polymerase chain reaction-based methods for specific diagnosis and/or the genetic characterization of Fasciola species.

Diagnosis of human fascioliasis by stool and blood techniques: update for the present global scenario

Before the 1990s, human fascioliasis diagnosis focused on individual patients in hospitals or health centres. Case reports were mainly from developed countries and usually concerned isolated human infection in animal endemic areas. From the mid-1990s onwards, due to the progressive description of human endemic areas and human infection reports in developing countries, but also new knowledge on clinical manifestations and pathology, new situations, hitherto neglected, entered in the global scenario. Human fascioliasis has proved to be pronouncedly more heterogeneous than previously thought, including different transmission patterns and epidemiological situations. Stool and blood techniques, the main tools for diagnosis in humans, have been improved for both patient and survey diagnosis. Present availabilities for human diagnosis are reviewed focusing on advantages and weaknesses, sample management, egg differentiation, qualitative and quantitative diagnosis, antibody and antigen detection, post-treatment monitoring and post-control surveillance. Main conclusions refer to the pronounced difficulties of diagnosing fascioliasis in humans given the different infection phases and parasite migration capacities, clinical heterogeneity, immunological complexity, different epidemiological situations and transmission patterns, the lack of a diagnostic technique covering all needs and situations, and the advisability for a combined use of different techniques, at least including a stool technique and a blood technique.

Development of two antibody detection enzyme-linked immunosorbent assays for serodiagnosis of human chronic fascioliasis

Coprological examination based on egg detection in stool samples is currently used as the gold standard for the diagnosis of human fascioliasis. However, this method is not effective during the acute phase of the disease and has poor sensitivity during the chronic phase. Serodiagnosis has become an excellent alternative to coprological examination in efforts to combat the effects of fascioliasis on human and animal health. Two novel recombinant Fasciola hepatica proteins, i.e., a ferritin (FhFtn-1) and a tegument-associated protein (FhTP16.5), were used as antigens to develop in-house enzyme-linked immunosorbent assay (ELISA) methods. The assays were optimized and validated using 152 serum samples from humans with a known infection status, including healthy subjects, patients with chronic fascioliasis, and patients with other parasitic diseases. The FhFtn-1 ELISA was shown to be 96.6% sensitive and 95.7% specific; the respective parameters for the FhTP16.5 ELISA were 91.4% and 92.4%. The performances of the FhFtn-1 and FhTP16.5 ELISAs were compared with that of an available commercial test (the DRG test) using a subset of serum samples. Our in-house tests were slightly more sensitive than the DRG test in detecting antibodies against F. hepatica, but the differences were not statistically significant. In conclusion, the present study provides evidence for the potential of the FhFtn-1 and FhTP16.5 ELISAs as diagnostic tools for human fascioliasis, as might be implemented in conjunction with standard assays for large-scale screenings in areas where the disease is endemic and for the detection of occasional cases in clinical laboratories.

Hepatic mass caused by Fasciola hepatica: a tricky differential diagnosis

Fascioliasis is a zoonotic infestation caused by the trematode fasciola hepatica. It presents a wide spectrum of clinical pictures ranging from fever and eosinophilia to ambiguous gastrointestinal symptoms in the acute phase. However, it may often be overlooked, especially in the acute phase, because of uncertain symptoms. Fasciola hepatica can have an initial presentation similar to the presentation of malignancy. Here, we report a case of a hepatic mass caused by fasciola hepatica.

Eosinophilic granulomatous gastrointestinal and hepatic abscesses attributable to basidiobolomycosis and fasciolias: a simultaneous emergence in Iraqi Kurdistan

Background

Deep eosinophilic granulomatous abscesses, as distinguished from eosinophilic subcutaneous abscesses, are rare. Most reports are from the Far-East and India where the most commonly attributed cause is Toxocara. Sulaimaniyah in Northeastern Iraq has experienced an outbreak of eosinophilic granulomatous liver and gastrointestinal (GI) abscesses beginning in 2009. The purpose of this study was to determine the etiology and guide treatment.

Methods

The study was an ongoing investigation of patients having a histopathologic diagnosis of eosinophilic granulomatous abdominal abscesses in Sulaimaniyah hospitals from May 2009 to August 2012. Tissues were examined for organisms, and Enzyme Linked Immunoabsorbent Assays (ELISA) were performed for serum antibodies to Fasciola hepatica, Toxocara, and Echinococcus granulosus.

Results

Fourteen patients had granulomatous inflammation surrounding a central necrotizing eosinophilic exudate identified in surgical pathology specimens from abdominal surgeries. Two children and four adults had abscesses that formed GI masses. These patients included a 39 year old male with oropharyngeal and transverse colon disease, and a 48 year old male with liver and GI abscesses. All sites demonstrated a Zygomycete fungus surrounded by eosinophilic Splendori-Hoeppli material consistent with basidiobolomycosis. Five of the six patients with fungal disease were treated by surgery and 4 to 7 months of itraconozol. One child died of intestinal perforation while receiving IV amphotericin B; two adults required additional surgery for recurrent GI obstruction. Eight patients had isolated liver abscesses with no organisms identified by histopathology: ELISA results for F. hepatica were positive for five, borderline for one, and negative for two patients. These eight patients were treated for fascioliasis by surgical resection of localized abscesses and albendazol. One patient serologically positive for F. Hepatica was found to have a common duct fluke two years after initial diagnosis. Serological testing for Toxocara and Echinococcus granulosus was negative in all 14 patients.

Conclusions

Basidiobolomycosis and F. hepatica are implicated as the cause of abdominal eosinophilic granulomatous abscesses in 12 of 14 patients identified over a period of 40 months in northern Iraq. Treatment was complicated by chronic biliary tract disease in fascioliasis and perforation and recurrent intestinal obstruction with basidiobolomycosis.

Direct, immunological and molecular techniques for a fasciolosis survey in a rural area of San Luis, Argentina

Fasciolosis is a zoonosis caused by the trematode Fasciola hepatica, prevalent in cattle, that is actually emerging as a cause of disease in humans. The goal of this work was to describe the characteristics of fasciolosis in arroyo El Juncal region, La Toma, San Luis province, Argentina. In order to get this objective, a transversal, quantitative study was carried out by a fieldwork that allowed the collection of data, human, animal, and environmental samples. The materials were processed by direct, immunological and/or molecular diagnostic techniques. According to the geographical characteristics and in presence of all the definitive and intermediate hosts, reservoirs, and sources of infection, it was possible to describe the persistence of fasciolosis in the area. The prevalence was 11.90 % in humans (by serology), 5.26 % in cattle (by coprological analysis) and 61.76 % in snails (by PCR). The situation that was found for this area indicates that any measure of intervention for the control of this zoonosis should be adopted by multidisciplinary teams.

Evaluation and characterization of Fasciola hepatica tegument protein extract for serodiagnosis of human fascioliasis

Tegument protein extract from Fasciola hepatica adult flukes (FhTA) was obtained and assessed for its potential as a diagnostic agent for the serological detection of human fascioliasis using an indirect enzyme-linked immunosorbent assay (ELISA). In an analysis of sera from 45 patients infected with F. hepatica, sera from 41 patients with other parasitic infections, and sera from 33 healthy controls, the FhTA-ELISA showed sensitivity, specificity, and accuracy of 91.1%, 97.3%, and 95%, respectively. Specific IgG1 and IgG4 were the antibody isotypes mainly detected in sera from patients with fascioliasis. Polypeptides of 52, 38, 24 to 26, and 12 to 14 kDa were identified by Western blotting as the most immunoreactive components of the FhTA. A proteomic approach led us to identify enolase, aldolase, glutathione S-transferase, and fatty acid binding protein as the major immunoreactive components of the FhTA.

Diagnostic potential ofFasciola gigantica-derived 14.5 kDa fatty acid binding protein in the immunodiagnosis of bubaline fascioliasis

The 14.5 kDa fatty acid binding protein (FABP) was isolated from the crude extract of adultFasciola giganticaworms. Polyclonal anti-FABP IgG was generated in rabbits immunized with prepared FABP antigen. Sandwich enzyme-linked immunosorbent assay (ELISA) was applied to detect coproantigen in stools and circulatingFasciolaantigen (CA) in sera of 126 water buffaloes by using purified and horseradish peroxidase (HRP)-conjugated anti-FABP IgG. Sandwich ELISA sensitivity was 96.97% and 94.95%; while specificity was 94.12% and 82.35% for coproantigen and CA detection, respectively. However, sensitivity and specificity of the Kato–Katz technique was 73.74% and 100%, respectively. The diagnostic efficacy of sandwich ELISA was 96.55% and 93.1% for coproantigen and CA detection, respectively. In contrast, the diagnostic efficacy of the Kato–Katz technique was 77.59%. In conclusion, these results demonstrate that the purified 14.5 kDa FABP provides a more suitable antigen for immunodiagnosis of early and current bubaline fascioliasis by using sandwich ELISA.

Biochemical characterization and differential expression of a 16.5-kilodalton tegument-associated antigen from the liver fluke Fasciola hepatica

A cDNA encoding a 16.5-kDa protein termed FhTP16.5 was identified by immunoscreening of a cDNA library from Fasciola hepatica adult flukes using pooled sera from rabbits infected with F. hepatica for 4 weeks. Quantitative reverse transcriptase PCR (qPCR) analysis revealed that FhTP16.5 is not expressed in unembryonated eggs. It is poorly expressed in miracidia and highly expressed at the juvenile and adult stages; however, significant differences were found between the expression levels of FhTP16.5 in juveniles versus adult flukes. Recombinant FhTP16.5 was expressed at high levels in Escherichia coli, purified by affinity chromatography, and used to raise anti-FhTP16.5 polyclonal antibodies in rabbits. Immunoblot analysis using the anti-FhTP16.5 IgG antibody identified FhTP16.5 in crude and tegumental extracts and in excretory-secretory products of F. hepatica. The protein was not detected in crude extracts of Schistosoma mansoni or Schistosoma japonicum. Antibodies to FhTP16.5 were detected in the sera of rabbits at 3 to 12 weeks of F. hepatica infection as well as in the sera of humans with chronic fascioliasis; these findings suggest that FhTP16.5 could be a good antigen for serodiagnosis of fascioliasis. Immunohistochemistry demonstrated that FhTP16.5 localizes to the surface of the tegument of various developmental stages and in parenchymal tissues of the adult fluke. Such specific localization makes FhTP16.5 an attractive target for immunoprophylaxis or chemotherapy.

Development and evaluation of a new lateral flow immunoassay for serodiagnosis of human fasciolosis

BACKGROUND

Human fasciolosis is a re-emerging disease worldwide and is caused by species of the genus Fasciola (F. hepatica and F. gigantica). Human fasciolosis can be diagnosed by classical coprological techniques, such as the Kato-Katz test, to reveal parasite eggs in faeces. However, although 100% specific, these methods are generally not adequate for detection of acute infections, ectopic infections, or infections with low number of parasites. In such cases immunological methods may be a good alternative and are recommended for use in major hospitals where trained personnel are available, although they are not usually implemented for individual testing.

METHODOLOGY/PRINCIPAL FINDINGS

We have developed a new lateral flow test (SeroFluke) for the serodiagnosis of human fasciolosis. The new test was constructed with a recombinant cathepsin L1 from F. hepatica, and uses protein A and mAb MM3 as detector reagents in the test and control lines, respectively. In comparison with an ELISA test (MM3-SERO) the SeroFluke test showed maximal specificity and sensitivity and can be used with serum or whole blood samples.

CONCLUSIONS/SIGNIFICANCE

The new test can be used in major hospitals in hypoendemic countries as well as in endemic/hyperendemic regions where point-of-care testing is required.

Fasciola hepatica saposin-like protein-2-based ELISA for the serodiagnosis of chronic human fascioliasis

An indirect enzyme-linked immunosorbent assay (ELISA) was developed and evaluated for its diagnostic ability to detect human IgG antibodies against Fasciola hepatica saposin-like protein-2. The assay was compared with an indirect ELISA with excretory-secretory products (FhES) from adult F. hepatica. In an analysis of the sera of 37 patients infected with F. hepatica, 40 patients with other parasitic infections, and 50 healthy controls, the sensitivity of both ELISA assays was 100%. However, the FhSAP2-based ELISA was more specific (95.6%) than the FhES-ELISA (91.9%). These results demonstrated that FhSAP2 can be used in the serodiagnosis of chronic human fascioliasis with the additional advantage of being relatively cheap and easy to produce. Studies are in progress to evaluate this FhSAP2-ELISA assay in a large-scale prevalence surveys in endemic areas.

Human fascioliasis in Argentina: retrospective overview, critical analysis and baseline for future research

In Argentina, human fascioliasis has never been adequately analysed, although having a physiography, climate, animal prevalences and lymnaeids similar to those of countries where the disease is endemic such as Bolivia, Peru and Chile. We performed a literature search identifying 58 reports accounting for 619 cases, involving 13 provinces, their majority (97.7%) from high altitudes, in central mountainous areas and Andean valleys, concentrated in Cordoba (430 cases), Catamarca (73), San Luis (29) and Mendoza (28), the remaining provinces being rarely affected. This distribution does not fit that of animal fascioliasis. Certain aspects (higher prevalence in females in a local survey, although a trend non-significant throughout Argentina) but not others (patient's age 3-95 years, mean 37.1 years) resemble human endemics in Andean countries, although the lack of intensity studies and surveys in rural areas does not allow for an adequate evaluation. Human infection occurs mainly in January-April, when higher precipitation and temperatures interact with field activities during summer holidays. A second June peak may be related to Easter holidays. The main risk factor appears to be wild watercress ingestion (214) during recreational, weekend outings or holiday activities, explaining numerous family outbreaks involving 63 people and infection far away from their homes. Diagnosis mainly relied on egg finding (288), followed by serology (82), intradermal reaction (63), surgery (43), and erratic fluke observation (6). The number of fascioliasis-hydatidosis co-infected patients (14) is outstanding. Emetine appears as the drug most used (186), replaced by triclabendazole in recent years (21). Surgery reports are numerous (27.0%). A long delay in diagnosis (average almost 3.5 years) and high lithiasis proportion suggest that many patients are frequently overlooked and pose a question mark about fascioliasis detection in the country. High seroprevalences found in recent random surveys suggest human endemic situations. This analysis highlights that human fascioliasis may have been overlooked in the past and its real epidemiological situation in high risk rural, mainly altitudinal areas, may currently be underestimated. Results provide a valuable baseline on which to design appropriate multidisciplinary studies on humans, animals and lymnaeids to assess up to which level and in which areas, human fascioliasis may represent a health problem in Argentina.

Fasciola hepatica and Schistosoma mansoni: identification of common proteins by comparative proteomic analysis

It is not unusual to find common molecules among parasites of different species, genera, or phyla. When those molecules are antigenic, they may be used for developing drugs or vaccines that simultaneously target different species or genera of parasite. In the present study, we used a proteomic-based approach to identify proteins that are common to adult Fasciola hepatica and Schistosoma mansoni. Whole-worm extracts from each parasite were separated by 2-dimensional electrophoresis (2-DE), and digital images of both proteomes were superimposed using imaging software to identify proteins with identical isoelectric points and molecular weights. Protein identities were determined by mass spectrometry. Imaging and immunoblot analyses identified 28 immunoreactive proteins that are common to both parasites. Among these molecules are antioxidant proteins (thioredoxin and glutathione-S-transferase), glycolytic enzymes (glyceraldehyde 6-phosphate dehydrogenase and enolase), proteolytic enzymes (cathepsin-L and -D), inhibitors (Kunitz-type, Stefin-1), proteins with chaperone activity (heat shock protein 70 and fatty acid-binding protein), and structural proteins (calcium-binding protein, actin, and myosin). Some of the identified proteins could be used to develop drugs and vaccines against fascioliasis and schistosomiasis.

Leucine aminopeptidase is an immunodominant antigen of Fasciola hepatica excretory and secretory products in human infections

The liver fluke Fasciola hepatica parasitizes humans and ruminant livestock worldwide, and it is now being considered a reemerging zoonotic disease, especially in areas in which it is endemic, such as South America. This study investigates the immune response to excretory and secretory products produced by F. hepatica in a group of patients from the Peruvian Altiplano, where the disease is highly endemic. Using a proteomic approach and immunoblotting techniques, we have identified the enzymes leucine aminopeptidase (LAP) and phosphoenolpyruvate carboxykinase as immunodominant antigens recognized by sera from fasciolosis patients. An indirect enzyme-linked immunosorbent assay using recombinant LAP as the antigen was developed to check sera from individuals of this region. Our results demonstrate that LAP produces a specific and strong reaction, suggesting its potential use in the serologic diagnosis of F. hepatica infections in humans.

Fasciola hepatica case with hemobilia

Fasciola hepatica (FH) can lead to important hepatobiliary diseases. Here we present a case of hemobilia associated with biliary FH, which is quite a rare case. The 41-year-old patient, who underwent common bile duct exploration due to hemobilia, was found to have arterial bleeding associated with ulcer caused by a dead parasite in the common bile duct. Hemobilia is a very rare complication associated with FH. When searching for the cause of hemobilia, FH should be considered.

Does Fasciola hepatica infection modify the response of acute hepatitis C virus infection to IFN-alpha treatment?

Immunologic response to acute hepatitis C is mainly a Th1 response, whereas fasciolopsiasis is associated with a diverse T-cell response. Interferon-alpha has immunomodulatory effects and enhances Th1 immune response. Fasciola infection could theoretically interfere with the Th1 immune response, even when acquired after an initial response to interferon-alpha treatment for acute hepatitis C virus (HCV) infection. We report here the case of a male patient who acquired Fasciola hepatica infection after an initial response to IFN-alpha therapy with a favorable outcome.

Asymptomatic fascioliasis

A 72-year-old Japanese man displayed asymptomatic eosinophilia for 4 months. Computed tomography showed multiple space-occupying lesions in the liver. Zoonotic liver flukes were suspected based on occupational exposure to cattle, serological and radiological findings. Immunological examination was helpful in diagnosing the disease and laparoscopy was crucial in confirming Fasciola hepatica and excluding the possibility of malignant hepatic tumors. Human fascioliasis was finally diagnosed and praziquantel administered. Blood eosinophilia resolved within 4 months and liver tumors almost disappeared within 12 months. From our experience, laparoscopy with liver biopsy is very important for diagnosing human fascioliasis, particularly for asymptomatic fascioliasis.

Liver, spleen, pancreas and kidney involvement by human fascioliasis: imaging findings

Background

Fasciola hepatica primarily involves the liver, however in some exceptional situations other organs have been reported to be involved. The ectopic involvement is either a result of Parasite migration or perhaps eosinophilic reaction.

Case presentation

Here we report a known case of multiple myeloma who was under treatment with prednisolone and melphalan. He was infected by Fasciola hepatica, which involved many organs and the lesions were mistaken with metastatic ones.

Discussion

Presented here is a very unusual case of the disease, likely the first case involving the pancreas, spleen, and kidney, as well as the liver.

OPTIMIZED SERODIAGNOSIS OF SHEEP FASCIOLIASIS BY FAST-D PROTEIN LIQUID CHROMATOGRAPHY FRACTIONATION OF FASCIOLA HEPATICA EXCRETORY–SECRETORY ANTIGENS

Current methods for the serodiagnosis of sheep fascioliasis show suboptimal sensitivity, specificity, or both. With the aim of developing an improved method, we fractionated native Fasciola hepatica excretory-secretory antigens (ESAs) by size-exclusion FPLC (fast protein liquid chromatography) on a Superdex 75 HR 10/30 column and then tested the serodiagnostic value of the antigens contained in each one of the 4 peaks obtained (peaks I-IV). Serodiagnostic value was assessed using sera from sheep naturally infected with F. hepatica (group A); sera from the individuals of a fluke-free herd (most of which also had other intestinal nematodes, lung nematodes, Moniezia spp., and/or Cysticercus tenuicollis) sera from a fluke-free herd (group B); sera from lambs experimentally infected with 10-40 F. hepatica metacercariae (group C); and sera from uninfected control lambs (group D). Enzyme-linked immunosorbent assay (ELISA) with peak I or II as target antigens (and to a lesser extent with peak III as target) showed reactivity with negative sera, so that it was not possible to establish cutoff values discriminating infected and uninfected animals. In contrast, when peak IV was used as target, a low cutoff value of 0.235 optical density units (mean + 4 SD) discriminated infected and uninfected animals, with 100% sensitivity and 100% specificity. ELISA with peak IV as a target identified infected animals (even animals that had received only 10 metacercariae) within 3-5 wk of infection and subsequently throughout the rest of the 14-wk monitoring period. In Western blotting analysis, again only the antigens contained in peak IV (range 7-40 kDa, under reducing conditions) were specific for diagnosis of infected animals. These results indicate that molecular sieving of F. hepatica ESAs by this procedure is a fast, simple, reproducible way of obtaining antigens useful for serodiagnosis of sheep fascioliasis.

Diagnostic imaging in sheep hepatic fascioliasis: ultrasound, computer tomography and magnetic resonance findings

Radiological features and biochemical changes were investigated during the parenchymal and ductal phases of chronic Fasciola hepatica infection in sheep. The activities of plasma aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and gamma-glutamyl transpeptidase (GGT), plasma levels of IgG anti- F. hepatica and serial ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) findings were studied in eight sheep infected with 150 F. hepatica metacercariae. Experimental fluke infection provoked an increase in plasma level of IgG directed against F. hepatica and in plasma LDH and AST activities from 4 weeks after infection. Enzyme activities did not significantly differ from the baseline after 15 and 12 weeks for LDH and AST, respectively. GGT activity increased from 9 weeks postinfection and still remained significantly elevated at 18 weeks. In the parenchymal phase, both CT and MRI showed nodular lesions in five animals and MRI could also detect early tracks in the subcapsular area in three sheep. Ultrasound findings were nonspecific in this phase. Ductal dilatation was shown by ultrasound, CT and MRI in almost all animals, although MRI was inferior to CT in depicting a mild ductal dilatation. Moving echogenic forms in the dilated bile ducts were observed by ultrasound from 9 weeks postinfection in seven of the eight sheep. Moving worms were only demonstrated in four sheep at CT and in a single sheep at MRI. This study shows that radiological findings may be useful in studies of fluke-induced liver damage.

Immunodiagnosis of fasciolosis using recombinant procathepsin L cystein proteinase

Cathepsin L1, a cysteine protease secreted by the gastrodermis of juvenile and adult Fasciola hepatica, was expressed in Escherichia coli as a fusion protein containing the proregion, supplied with six histidyl residues at the N-terminal end (rproCL1). In this study we tested its potential as antigen for the serologic diagnosis of F. hepatica infections by enzyme-linked immunosorbent assay (ELISA). The analyzed human sera included 16 positive samples, 99 negative controls and 111 from individuals affected by other parasitic and non parasitic diseases. The sensitivity and specificity of the rproCL1-ELISA were 100%. We also assessed the ability to detect antibodies in sera from 10 experimentally infected sheep, obtaining preliminary results that shown a response since the third week post infection in all the studied animals. Therefore, the recombinant rproCL1-based ELISA could be a standardized test for the accurate diagnosis of fasciolosis.