IgG response in natural and experimental infections of cattle with Fasciola gigantica.

A specific IgG response was detectable in serum and bile of cattle infected with Fasciola gigantica. Although there was an increase in both specific and total IgG concentration in the sera of fluke-infected cattle, there was no significant correlation between IgG1 concentration and the worm burden (r = 0.17; P greater than 0.05) in chronic fascioliasis. However, there was a highly significant correlation between the levels of IgG1 in the serum and bile of infected cattle (r = 0.87; P less than 0.01), indicating that the presence of IgG1 in the bile may be due to a leakage of serum antibody into the bile duct.