Assessing the validity of an ELISA test for the serological diagnosis of human fascioliasis in different epidemiological situations

Abstract

Objectives To improve the diagnosis of human fascioliasis caused by Fasciola hepatica and Fasciola gigantica, we evaluated the diagnostic accuracy of an enzyme‐linked immunosorbent assay (ELISA), with Fasciola antigen from the adult liver fluke, for the detection of IgG against fascioliasis in human sera. Methods The sera of 54 fascioliasis cases, originating from three endemic areas, were used in this evaluation: (i) a hyperendemic F. hepatica area where humans usually shed a great number of parasite eggs in faeces (11 sera); (ii) an epidemic F. hepatica area where humans usually shed small amounts of parasite eggs (24 sera) and (iii) an overlap area of both Fasciola species and where human shedding of parasite eggs in faeces is usually scarce or non‐existent (19 sera). One hundred and sixty‐eight patients with other parasitic infections and 89 healthy controls were also analysed. Results The respective sensitivity and specificity of this assay were 95.3% (95% confidence intervals, 82.9–99.2%) and 95.7% (95% confidence intervals, 92.3–97.5%). No correlation between egg output and the OD450 values of the F. hepatica IgG ELISA test was observed. Conclusions This test could be used both as an individual serodiagnostic test for human fascioliasis when backed up by a compatible clinical history together with a second diagnostic technique for other cross‐reactive helminth infections, and in large‐scale epidemiological studies of human fascioliasis worldwide.

Development and Evaluation of a Single-Step Duplex PCR for Simultaneous Detection of Fasciola hepatica and Fasciola gigantica (Family Fasciolidae, Class Trematoda, Phylum Platyhelminthes)

“…can elicit a specific antibody response which can be detected by Ab-ELISA as early as 1 to 2 weeks after infection (44), while shedding eggs are found in feces 10 to 12 weeks postinfection (30). Antibody detection tests are useful for determining seroprevalence in epidemiological studies but are not necessarily good indicators of active infection (44). A review (11) suggested that the most accurate, sensitive, and specific information could be determined easily and with low costs, making DNA-based tools available to investigate the epidemiology of the liver fluke in a laboratory with limited financial resources (11).…”

“…Fasciola spp. can elicit a specific antibody response which can be detected by Ab-ELISA as early as 1 to 2 weeks after infection (44), while shedding eggs are found in feces 10 to 12 weeks postinfection (30). Antibody detection tests are useful for determining seroprevalence in epidemiological studies but are not necessarily good indicators of active infection (44).…”

“…While often very sensitive, serological methods do not track cure very well and may not provide an accurate indication of active infection: infected individuals can remain seropositive for considerable lengths of time after treatment (44). Molecular methods targeting eggs in stool samples will be useful for this.…”

Development of Two Antibody Detection Enzyme-Linked Immunosorbent Assays for Serodiagnosis of Human Chronic Fascioliasis

“…FhFtn-1 and FhTP16.5 ELISAs were compared with an ELISA (DRG test; DRG Instruments GmbH, Germany) that is based on excretory-secretory products (ESPs) from adult F. hepatica, mainly containing cysteine proteases (27,28). This test was used with a subset of 86 serum samples selected among those that had been used previously to validate the FhFtn-1 and FhTP16.5 ELISAs.…”

“…One of these assays (Ildana Biotech) uses recombinant forms of cathepsin L1 as antigens and has been optimized for detection of antibodies in the serum and milk of cattle (26). Others methods, as the AccuDiag Fasciola IgG ELISA (Diagnostic Automation/Cortez Diagnostic, Inc.), Bio-X, and DRG (DRG Instruments GmbH, Germany) kits, have been optimized for detection of antibodies in the sera of cattle (27) and humans (28). These assays use ESPs as antigens, which could limit their usefulness due to cross-reactions with other parasites (27,28).…”