MM3-ELISA Detection of Fasciola hepatica Coproantigens in Preserved Human Stool Samples

Abstract

In this study, we evaluate the MM3-COPRO method for detection of Fasciola coproantigens in human fecal samples, and the usefulness of a new preservative/diluent, CoproGuard, developed for preservation of Fasciola coproantigens. The MM3-COPRO assay was evaluated with 213 samples from healthy patients, 30 Fasciola positive fecal samples (according to the Kato-Katz method), and 83 samples from patients with other parasitic infections. All Fasciola positive specimens were detected with the MM3-COPRO assay (100% sensitivity) and there was no cross-reactivity with other common parasites present in the clinical specimens analyzed (100% specificity). The use of CoproGuard enhanced coproantigen extraction without affecting the detection limit of the assay, and the antigenicity of Fasciola coproantigens in fecal samples stored at 37 degrees C was retained throughout the entire observation period (120 days). We concluded that the MM3-COPRO ELISA combined with the use of CoproGuard may be a very useful tool for the diagnosis of human fascioliasis.

Immunodetection of Fasciola gigantica Circulating Antigen in Sera of Infected Individuals for Laboratory Diagnosis of Human Fascioliasis

“…Significant correlations of Fasciola antigens with parasite burden in animals (23,56) and also with egg counts in human fascioliasis (25,51) have been demonstrated. In contrast, Ubeira et al (24) reported that there was no correlation between egg counts and antigens levels in stool as measured by ELISA, as the egg excretion is probably more erratic in patients with chronic infections. However, the presence of a highly significant correlation between circulating Fasciola antigen levels and parasite egg count which is presumably dependent on the number of flukes in the host is of crucial importance to the use of the developed assay to monitor the efficiency of flukicide treatment in Fasciola-infected individuals and to assess potential new vaccine efficacy.…”

“…Of note, all serologic tests based on the 27-kDa antigen were developed and optimized with an emphasis on the detection of antibodies to F. hepatica (12,13,44,45). However, the direct detection of Fasciola antigens secreted by the living flukes has apparent advantages over antibody detection tests, in that antigenemia implies active infection, and this approach has the ability to assess efficacy of chemotherapy and determine the effectiveness of future vaccines (24,(46)(47)(48).…”

“…In that sense, the direct detection of parasite antigens in stool (coproantigens) or serum (circulating antigens) of Fasciola-infected animals or humans has been reported as a new alternative approach with greater diagnostic accuracy (22)(23)(24)(25)(26). In our previous study, we identified a 26-to 28-kDa circulating antigen in sera of cattle infected with F. gigantica by using specific rabbit IgG antiserum (22).…”

Neurological and Ocular Fascioliasis in Humans

“…At present, coproantigen tests have proved to be very useful for human diagnosis of infection by both F. hepatica and F. gigantica (Ubeira et al, 2009;Valero et al, 2009b). Moreover, a coproantigen test, when positive, assures the presence of the flukes in the liver, that is, when negative only ectopic forms may be responsible for positivity of the specific serological tests.…”

“…Additionally, a new preservative/diluent, CoproGuard, developed for preservation of Fasciola coproantigens, has demonstrated to enhance coproantigen extraction without affecting the detection limit of the assay, the antigenicity of Fasciola coproantigens in faecal samples being retained throughout long periods. Thus, the combination of CoproGuard with a coproantigen test becomes a very useful tool for the diagnosis of human fascioliasis (Ubeira et al, 2009). …”