Development of host resistance to Fasciola hepatica after the elimination of primary infection with diamphenethide.

We studied the specificity of the individual developmental stages of Fasciola hepatica for evoking immune response of the host to reinfection with this parasite, whereby the primary infection was eliminated by a dose of 150 mg/kg diamphenethide administered in various intervals. In rats we observed a state of hypersensitivity demonstrated by retarded migration and growth of the flukes and the reduction in the number of sexually developed parasites. The changes were most marked, if the elimination of the immunizing infection followed 8-10 weeks after primary infection.