Development and application of a fecal antigen diagnostic sandwich ELISA for estimating prevalence of Fasciola gigantica in cattle in central Java, Indonesia.

The purpose of this study was to compare the sensitivity and specificity of an ELISA test to detect Fasciola gigantica antigens (coproantigens) in bovine feces, with fecal egg counting and an ELISA for detecting anti-F. gigantica antibodies in serum. Monoclonal antibodies to cathepsin L were generated and used to capture this antigen in feces of infected cattle. Blood, feces, and livers were collected from 150 cattle at an abattoir in Jakarta, Indonesia, for anti-Fasciola antibodies, coproantigen detection, and F. gigantica egg and worm counts. Fluke recovery varied from 1 to 426 per host, with a mean of 32 flukes. The results showed that the sensitivity and specificity of coproantigen detecting ELISA (95 and 91%, respectively) was better than the anti-F. gigantica antibody ELISA (91 and 88%, respectively) and to fecal egg counting (87 and 100%, respectively). The coproantigen ELISA was able to detect 100% of the cattle with >15 flukes. A survey of 305 cattle in central Java over a 10-mo period validated this test in the field, demonstrating a high prevalence of fascioliasis and establishing the test as a useful diagnostic method to determine patent F. gigantica infections in cattle.

Detection of coproantigens by sandwich ELISA in sheep experimentally infected with Fasciola gigantica.

Two monoclonal antibodies to Fasciola gigantica excretory/secretory (ES) antigens were used in a sandwich ELISA for the detection of Fasciola antigens in faeces of 9 sheep experimentally infected with 300 metacercariae of F. gigantica. The detection of coproantigens was found in four of the seven sheep within 5 weeks of infection, and within 7 weeks of infection coproantigens were detected in all seven of the sheep. This technique was compared to an indirect ELISA for the detection of anti-Fasciola ES antigen specific antibodies in serum. The anti-F. gigantica antibodies were detected within 3 weeks of infection in all of the infected sheep, suggesting a greater sensitivity to detect early infections. However, following anthelmintic treatment and removal of parasites, the anti-Fasciola antibody levels still remained high for at least 6 weeks when the study was terminated. In contrast, the levels of coproantigens were no longer detected in the faeces within 2 weeks of anthelmintic treatment. This study demonstrates that our sandwich ELISA for the detection of Fasciola coproantigens is able to detect immature fluke infections and more importantly, was able to detect patent infection of fasciolosis.