Designing and Developing Serological Test for the Diagnosis of Human Fascioliasis Using a New Recombinant Multi-epitope

PURPOSE

Fascioliasis is a common parasitic disease in humans and herbivores which is caused by Fasciola hepatica and Fasciola gigantica and has a worldwide distribution. Serological tests such as the enzyme-linked immunosorbent assay (ELISA) technique play a prominent role in the fast diagnosis of the disease. However, there are diagnostic limitations, including cross-reactivity with other worms, which decline the specificity of the results. This study aimed to evaluate the structure of a recombinant multi-epitope antigen produced from linear and conformational B-cell epitopes of three parasitic proteins with sera of individuals with fasciolosis, healthy controls, and those with other diseases to gain accurate sensitivity and specificity.

METHODS

After designing the multi-epitope structure of cathepsin L1, FhTP16.5, and SAP-2 antigens and then synthesizing, cloning, and expressing, the extracted purified protein was evaluated by indirect ELISA to detect IgG antibodies against Fasciola hepatica parasite among the sera of 39 serum samples of Fasciola hepatica, 35 healthy individual samples, and 20 samples of other types of parasitic diseases. The synthesized multi-epitope produced from cathepsin L1, FhTP16.5, and SAP-2 antigens was evaluated using the indirect ELISA.

RESULTS

The analysis of the samples mentioned for IgG antibody diagnosis against Fasciola hepatica showed 97.43% (95% confidence interval, 94.23-100%) sensitivity and 100% (95% confidence interval, 97-100%) specificity.

CONCLUSION

The recombinant B-cell multi-epitope with high antigenic potency may increase the specificity of epitopic peptides and ultimately help improve and develop indirect ELISA commercial kits for the diagnosis of fascioliasis in humans.

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.

Recent advances in the diagnosis, impact on production and prediction of Fasciola hepatica in cattle

Fasciola hepatica is a pathogenic trematode parasite of ruminants with a global distribution. Here, we briefly review the current epidemiology of bovine fasciolosis in Europe and discuss the progress made over the last decade in the diagnosis, impact on production and prediction of F. hepatica in cattle. Advances in diagnosis have led to significantly improved coprological and serological methods to detect presence of infection. Diagnostic test results have been correlated with intensity of infection and associated production losses, unravelling the impact on carcass weight and milk yield in modern cattle production systems. The economic impact of fasciolosis may, however, go beyond the direct impacts on production as evidence shows that F. hepatica can modulate the immune response to some co-infections. Control of bovine fasciolosis remains hampered by the limitations of the currently available flukicidal drugs: few drugs are available to treat dairy cows, many have low efficacies against juvenile stages of F. hepatica and there is evidence for the development of drug resistance. This makes research into the prediction of risk periods, and thus the optimum application of available drugs more pertinent. In this field, the recent research focus has been on understanding spatial risk and delivering region-specific spatial distribution maps. Further advances in epidemiological and economic research on bovine fasciolosis are expected to deliver farm-specific economic assessments of disease impact, to leverage non-chemotherapeutic management options and to enhance a more targeted use of anthelmintics.

The global burden of fasciolosis in domestic animals with an outlook on the contribution of new approaches for diagnosis and control

Fasciolosis is an economically important disease for livestock, as well as being zoonotic. Recent figures on the prevalence of this disease have caused alarm concerning its potential for an increased prevalence in the future. The prevalence of fascioliosis has been documented from different regions of the world, helping us identify areas where future research needs to be focused. This manuscript is a review of the current status of the disease, the pathogenic species involved, diagnostic techniques (with new modifications and comparative specificity, sensitivity, and rapidity of these tests), chemotherapy, and vaccination. This also encompasses inaccurate reports on vaccination and drug development as well as the latest technologies to find promising candidates for drugs and vaccines. Drugs with lower efficacy have been used on some farms which lead to exacerbation of the clinical disease, presumably due to the development of drug resistance. Future studies should be focused on (1) the use of the most reliable diagnostic tests for periodic monitoring of the disease, (2) insights of the ecobiology and transmission dynamics of the snail intermediate host and the best possible methods of their control, (3) in vitro and in vivo testing of chemotherapeutic compounds using sensitive methods, and (4) the identification of novel drug and vaccine candidates using modern molecular markers. This approach may help increase the reliability of chemotherapeutic agents and control nuisance, ultimately reducing the economic losses attributable to the livestock industry around the world.