Detection of circulating Fasciola gigantica antigen in experimental and natural infections of sheep with fasciolosis.

Detection of circulating Fasciola gigantica antigen was performed in sera of sheep with experimental and natural F. gigantica infections using the direct enzyme-linked immunosorbent assay method. Sera from sheep with monoinfections of Schistosoma bovis, Dicrocoelium hospes and Paramphistomum microbothrium were included in the assay to ascertain specificity. Circulating F. gigantica antigen (CFA) was detected as early as 1 week after infection in the experimentally infected sheep. No detectable CFA was observed 2 weeks after chemotherapy. Positivity rates of 82.5%, 12.5%, 10% and 10% were found in sera with monospecific infections of F. gigantica, P. microbrothrium, D. hospes and S. bovis, respectively. Acid treatment of the sera did not enhance the sensitivity of the assay.