Prevalence of natural ovine fasciolosis shown by demonstrating the presence of serum circulating antigens.

The prevalence of fasciolosis in sheep (Galicia, Northwest Spain) kept under field conditions was determined by using a sandwich-enzyme-linked immunosorbent assay (sELISA). Serum Fasciola hepatica circulating antigens were captured by means of a rabbit polyclonal IgG antibody to F. hepatica excretory/secretory products. Results were compared to those obtained by faecal sedimentation and an indirect ELISA (iELISA) and excretory/secretory antigens. Prevalences were 39.1% by sELISA, 30.4% by faecal sedimentation and 56% by iELISA; 83.3% of the sheep were positive to any one of the three tests. We observed that 59.5% of the sheep examined had active fasciolosis, 29.1% (117) had antigenaemia, 20.4% (82) passed eggs, and 40 (10%) were positive to both probes. We conclude that there is a high prevalence of fasciolosis in sheep from the studied region, and that the combination of sELISA and coprological sedimentation is extremely helpful for demonstrating current fasciolosis, so its application can be strongly recommended for epidemiological surveys.