Fas2-ELISA in the detection of human infection byFasciola hepatica

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.

Immunodiagnosis of cattle fascioliasis using a 27 kDa Fasciola gigantica antigen

Background and Aim:

Diagnosis of fascioliasis depends on clinical symptoms and routine laboratory tests. Recently, antibodies and circulating antigens of Fasciola were used for detecting active infections. Therefore, this study aimed to identify Fasciola gigantica antigens in the sera of infected cattle using Western blotting and enzyme-linked immunosorbent assay (ELISA) for an accurate diagnosis of cattle infected with F. gigantica.

Materials and Methods:

Serum samples were obtained from 108, 23, and 19 cattle infected with Fasciola gigantica, Paramphistomum cervi, and Strongylids, respectively, including 57 non-infected cattle that were used as healthy cattle for the study. Western blotting and ELISA were then used to detect circulating Fasciola antigens at 27 kDa.

Results:

The target epitope was detected in an F. gigantica adult-worm antigen preparation, excretory/secretory products, and serum from cattle infected with F. gigantica. However, it was absent in sera from P. cervi, Strongylids, and healthy cattle. The purified 27 kDa F. gigantica (FPA-27) antigen was also detected in cattle serum using ELISA with high degrees of sensitivity and specificity (94% and 82%, respectively), and the area under the receiver operating characteristic curve was 0.89 with a highly significant correlation of p<0.0001.

Conclusion:

The FPA-27 is proposed to be a promising candidate for the serodiagnosis of fascioliasis in cattle.

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.

Human fascioliasis presenting as liver abscess: clinical characteristics and management

BACKGROUND

Human fascioliasis, caused by the liver flukes F. hepatica, and F. gigantica, is a neglected tropical disease that causes health problems in many regions of the world. This disease can be classified as either acute or chronic based depending on the clinical manifestations and laboratory findings.

METHODS

We retrospectively reviewed the demographic data, clinical features, radiologic manifestations, and the response to specific treatment of patients diagnosed with hepatic fascioliasis as well as fasciola liver abscess in Thailand.

RESULTS

A total of 175 patients were included in the study, 126 patients were females (72%), while the mean age was 47.8 years (16-84 years). The most common symptoms were abdominal pain (74.9%), weight loss (29.1%) and fever (28%). Peripheral eosinophilia was observed in 92% of patients. The typical radiologic findings discovered conglomerated hypodensity which are rim-enhancing lesions located in the subcapsular and peripheral region of the liver. Most of patients were improved after a single dose of triclabendazole treatment. Adding antibiotic had no statistical impact on treatment outcome (p = 0.78).

CONCLUSIONS

Human fascioliasis presents with a wide clinical spectrum; therefore, a high index of suspicion is required to establish a correct diagnosis. Clinicians need to be aware of hepatic fascioliasis when patients in such endemic areas present as hypereosinophilia and typical liver imaging. Prompt specific treatments will contribute towards a satisfactory outcome in patients.

Design and expression of polytopic construct of cathepsin-L1, SAP-2 and FhTP16.5 proteins of Fasciola hepatica

The enzyme-linked immunosorbent assay (ELISA) technique can play an important role in the early detection of fascioliasis. However, they have some diagnostic limitations, including cross-reaction with other helminths. It seems that the combination of recombinant parasite proteins as antigen can reduce these problems. Hence, the present study was aimed to design and confirm the antigenic recombinant multi-epitope (rMEP) construct of three protein epitopes (linear and conformational B-cell epitopes) of the parasite using immunoinformatic tools. For this purpose, the tertiary structures of Fasciola hepatica cathepsin-L1, saposin-like protein 2 and 16.5-kDa tegument-associated protein were predicted using the I-TASSER server. Validation of the modelled structures was performed by Ramachandran plots. The antigenic epitopes of the proteins were achieved by analysing the features of the IEDB server. The synthesized gene was cloned into the pET-22b (+) expression vector and transformed into the Escherichia coli BL21. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was used to verify and analyse the expression of the rMEP protein. Western blotting was utilized to confirm rMEP protein immunogenicity in two forms, one using an anti-His tag antibody and the other with human pooled sera samples (fascioliasis, non-fascioliasis and negative control sera). Our results demonstrated that the rMEP designed for the three proteins of F. hepatica was highly antigenic, and immune-detection techniques confirmed the antigen specificity. In conclusion, the presented antigenic multi-epitope may be very helpful to develop serodiagnostic kits such as indirect ELISA to evaluate the proper diagnosis of fascioliasis in humans and ruminants.

Negative serology of Fasciola hepatica infection in patients with liver cancer in Peru: a preliminary report

INTRODUCTION

The etiology of several hepatocellular carcinoma (HCC) cases remains largely unknown. Although Fasciola hepatica has been associated with liver fibrosis in Latin America, it has not yet been associated with HCC. This study aimed to determine the existence of specific IgG antibodies against F. hepatica in the serum samples of HCC patients.

METHODS

In total, 13 serum samples from 13 HCC patients were screened using Fas2-ELISA.

RESULTS

Fas2-ELISA demonstrated negative results in all HCC patients included in this study.

CONCLUSIONS

The pre-existence of F. hepatica infection in HCC patients needs to be further investigated in epidemiological and experimental studies.

Production of Monoclonal Antibody Against Excretory-Secretory Antigen of Fasciola hepatica and Evaluation of Its Efficacy in the Diagnosis of Fascioliasis

Parasitological methods are not helpful for the diagnosis of fascioliasis in acute and invasive periods of the disease. Detection of coproantigens seems to be a suitable alternative approach in the diagnosis of fascioliasis. The present study aimed to develop a reliable antigen detection system, using monoclonal antibodies raised against excretory-secretory (ES) antigen of Fasciola hepatica, for the diagnosis of fascioliasis. Fasciola adult worms were collected from the bile ducts of infected animals. Species of the fluke was determined by polymerase chain reaction-restriction fragment length polymorphism (RFLP-PCR). ES antigen of F. hepatica was prepared. For production of monoclonal antibodies, mice were immunized with ES antigens of F. hepatica. Spleen cells from the immunized mice were fused with NS-1 myeloma cells, using polyethylene glycol. Hybridoma cells secreting specific antibody were expanded and cloned by limiting dilution. Moreover, polyclonal antibody was produced against F. hepatica ES antigen in rabbits. A capture enzyme-linked immunosorbent assay (ELISA) system, using produced monoclonal antibody, was designed and stool samples of infected animals along with control samples were tested by the system. The capture ELISA detected the coproantigen in 27 of 30 (90%) parasitologically confirmed fascioliasis cases, while 4 of 39 (10.25%) samples infected with other parasitic infections showed a positive reaction in this system. No positive reactivity was found with healthy control samples. Accordingly, sensitivity of 90% and specificity of 94.2% were obtained for the capture ELISA system. The results were compared with those obtained with commercial BIO-X ELISA, and a very good (kappa = 0.9) agreement was found between the commercial kit and the developed capture ELISA. Findings of this study showed that the produced monoclonal antibody has appropriate performance for the detection of Fasciola coproantigen in stool samples and can be appropriately used for the diagnosis of fascioliasis.

Ectopic Human Fasciola hepatica Infection by an Adult Worm in the Mesocolon

We report here an ectopic case of Fasciola hepatica infection confirmed by recovery of an adult worm in the mesocolon. A 56-year-old female was admitted to our hospital with discomfort and pain in the left lower quadrant of the abdomen. Abdominal CT showed 3 abscesses in the left upper quadrant, mesentery, and pelvic cavity. On surgical exploration, abscess pockets were found in the mesocolon of the sigmoid colon and transverse colon. A leaf-like worm found in the abscess pocket of the mesocolon of the left colon was diagnosed as an adult fluke of F. hepatica. Histologically, numerous eggs of F. hepatica were noted with acute and chronic granulomatous inflammations in the subserosa and pericolic adipose tissues. Conclusively, a rare case of ectopic fascioliasis has been confirmed in this study by the adult worm recovery of F. hepatica in the mesocolon.

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.

Immunodetection of Fasciola gigantica circulating antigen in sera of infected individuals for laboratory diagnosis of human fascioliasis

Currently, the laboratory diagnosis of human fascioliasis is based on the parasitological examination of parasite eggs in stool specimens and serological detection of specific antibodies in serum samples, which are often unreliable diagnostic approaches. Ideally, a sensitive and specific diagnostic test for Fasciola infection should be based on the detection of circulating Fasciola antigen, which implies active infection. Here, a 27-kDa-molecular-mass antigen was identified in a Fasciola gigantica adult worm antigen preparation, excretory-secretory products, and sera from F. gigantica-infected individuals, and it was not detected in antigenic extracts of other parasites and sera from noninfected individuals. The target antigen was isolated and partially characterized as a protein. Immunoperoxidase staining located the target epitope within teguments and guts of F. gigantica adult worms. The performance characteristics of a newly developed enzyme-linked immunosorbent assay (ELISA) based on F. gigantica circulating antigen detection in serum (FgCA-27 ELISA) were investigated using sera of 120 parasitologically diagnosed F. gigantica-infected individuals and 80 noninfected individuals. The area under the receiving operating characteristic (ROC) curve (AUC) for ELISA was significantly high (AUC = 0.961, P < 0.0001) for discriminating Fasciola-infected and noninfected individuals. The developed assay showed high degrees of sensitivity, specificity, and efficiency (>93%), and a significant correlation (r = 0.715, P < 0.0001) between antigen level and parasite egg count was shown. In conclusion, a 27-kDa Fasciola antigen was identified in sera of F. gigantica-infected individuals. A highly sensitive and specific Fasciola antigen detection assay, FgCA-27 ELISA, was developed for laboratory diagnosis of human fascioliasis.

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.

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.

Update on hepatobiliary flukes: fascioliasis, opisthorchiasis and clonorchiasis

PURPOSE OF REVIEW

Hepatobiliary flukes--Fasciola, Opisthorchis, Clonorchis- are a major public health problem in east Asia, east Europe, Africa and Latin America. The present review focuses on current knowledge of clinical, diagnostic and treatment aspects caused by hepatobiliary flukes that can be applied to current protocols in endemic areas.

RECENT FINDINGS

Specific risk factors and geographic areas for these flukes have been heavily reported recently, with millions of people infected worldwide. Human cases in nonendemic areas, related to immigration and the international food trade (i.e. raw vegetables and fish), have also been reported. Diagnostic imaging changes include track-like lesions that are a characteristic feature of acute fascioliasis on computed tomography scanning of the liver. Newly available diagnostic serological tests may detect early infection and, therefore, help reduce severe clinical complications such as recurrent cholangitis, cholecystitis, hepatic tumours, cysts, calcification, cholelithiasis, pancreatitis, most importantly, cholangiocarcinoma related to Opisthorchis viverrini and possibly Clonorchis sinensis, and liver fibrosis associated with Fasciola hepatica infections. Highly effective antiparasitic treatment is available for all flukes.

SUMMARY

There is a better understanding of risk factors, clinical manifestations and complications, novel diagnosis tests and effective treatment, which together should help reduce the morbidity and mortality of these infections.

Detection of antibodies against Fasciola hepatica in cirrhotic patients from Peru

The prevalence of Fasciola hepatica infection, in endemic countries, in patients with established cirrhosis is unknown. We hypothesized that, in endemic countries, the presence of fascioliasis may be detected in a serum pool of cirrhotic patients. Forty-four previously stored serum samples of patients with established liver cirrhosis, in the Hospital Nacional Cayetano Heredia in Lima, Peru, were collected from 1998 to 2003 and assessed for hepatitis B, C and fascioliasis antibodies (Fas2 ELISA). Hepatitis B surface antigen (HBsAg) was positive in 8.8% (n = 34), hepatitis B core antibody (anti-HBc) in 32.5% (n = 34), hepatitis C antibodies (anti-HCV) in 9.1% (n = 33), and 9.1% (n = 44) were Fas2 ELISA positive. This disease is an example of an emerging tropical infection which can be present in chronic liver diseases, requiring greater clinician awareness especially in endemic rural areas. Further clinical studies are warranted.

Fasciola hepatica in a New Zealander traveler

Fascioliasis is a reemerging zoonosis endemic in many parts of the world. Reports of imported fascioliasis by migrants into nonendemic countries are common, but tourists and business travelers are rarely afflicted. Here, we report a case of a New Zealander traveler who acquired the infection on a business trip.

Human fascioliasis: a case of hyperinfection and an update for clinicians

Fascioliasis is a foodborne trematode infection that affects patients worldwide causing both liver inflammation and biliary obstruction. In developed countries, the disease is rare but a number of focal outbreaks have been reported. Here, we report a case of human fascioliasis in which acute and chronic manifestations coexisted and discuss the newest evidence regarding pathogenesis, diagnostic approach, and treatment, with emphasis on strategies to control the incidence of this emergent disease.

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.

Preliminary antigenic characterisation of an adult worm vomit preparation of Fasciola hepatica by infected human sera

Fascioliasis is an emerging/re-emerging vector-borne disease with the widest known distribution. Approximately 17 million people are infected around the world, being the Andean region the most affected area. There is an important necessity to develop sensitive and specific diagnostic tools to treat patients early and to avoid complications. In this paper we evaluated the immune response of infected humans against two antigenic preparations: the total soluble extract (FhTSE) and the adult worm vomit (FhAWV) in order to identify antigenic fractions specific for Fasciola hepatica. Both preparations were processed by SDS-PAGE and Western blot with human sera with fascioliasis (F), other parasitosis and healthy individuals. In the immunoblot of FhTSE, sera F recognised 16 bands with MW between eight and 110 kDa, from which those of 8, 9, 10, 38, 45 and 57 kDa were specific. In the preparation FhAWV, sera F recognised nine bands with MW from eight to 85 kDa, from which those of 8, 12, 15 and 24 kDa were specific. Some bands of cross-reaction were evident with sera from patients with other parasitoses, more frequent with the FhTSE. Bands within the MW mentioned, particularly that of eight kDa, have been shown to be specific by others, and deserve additional characterisation for their potential use in immunodiagnosis.

THE USE OF MM3 MONOCLONAL ANTIBODIES FOR THE EARLY IMMUNODIAGNOSIS OF OVINE FASCIOLIASIS

This study reports a new capture ELISA (MM3-SERO) for the serodiagnosis of sheep fascioliasis, based on the use of the monoclonal antibody (mAb) MM3. Like our previously reported indirect ELISA method, based on the use of a FPLC-purified fraction (fraction IV) of the Fasciola hepatica excretion/secretion antigens (ESAs), this new test was able to detect animals infected with very small numbers of metacercariae (5-40) and showed no cross-reaction with sera from sheep infected with other parasites, i.e., Moniezia spp., Cysticercus tenuicollis, and Dicrocoelium dendriticum. In contrast with these 2 methods, some sera (mainly those obtained from animals infected with D. dendriticum) showed high reactivities in indirect ELISA with whole F. hepatica ESAs used as control. Interestingly, the MM3-SERO ELISA has a better signal-to-noise ratio than the fraction-IV ELISA, thus allowing detection of seroconversion in infected sheep on average 1 wk earlier (3.2 +/- 0.4 wk postinfection [PI] for MM3-SERO ELISA vs. 4.2 +/- 0.9 wk PI for fraction IV ELISA). Moreover, the antibody response detected with MM3-SERO ELISA was more uniform, with seroconversion always occurring at 4 wk PI in sheep with 1-2 flukes and at 3 wk PI in sheep with more than 2 flukes. The MM3-SERO ELISA was also used to evaluate the kinetics of antibody response against MM3-recognized antigens in sera from sheep experimentally infected with F. hepatica and then treated with triclabendazole. Our results showed that antibody levels dropped by about 25% during the 4-wk observation period following the flukicide treatment, whereas they remained invariably high in all sheep left untreated. We conclude that the MM3-SERO ELISA is a 100% sensitive and 100% specific test for the early serodiagnosis of sheep fascioliasis. Preliminary studies in our laboratory seem to indicate that this method may also be useful for the determination of anti-F. hepatica antibodies in serum and milk of other ruminants. A commercial version of MM3-SERO is currently available from BIO X Diagnostics (La Jemelle, Belgium).