Experimental cross infections of Fasciola hepatica in lambs and calves.

The effects of experimental infections with Fasciola hepatica of ovine and bovine origin in homologous and heterologous hosts and in uninfected controls were compared; groups comprised 5 animals each. The effects of the infections were monitored by biweekly determinations of packed cell volumes (PCV), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), gamma glutamyl transpeptidase (GGT), serum iron, bilirubin levels, alkaline phosphatase (AlP) and total serum protein levels. Infected animals showed changes in SGOT, SGPT and GGT activity levels, and GGT activity levels, and infected lambs showed changes in PCV and AlP. However, no no significant differences in these serum levels between infected host groups were attributable to fluke strain. At necropsy, calves infected with ovine and bovine strains on an average had about the same number of flukes, but lambs infected with a high dose of the bovine strain on the average had nearly twice the number of flukes as those infected with ovine strain. Weight gains did not differ within host groups; liver damage was extensive in all infected animals. On the basis of these experiments, the pathogenicity of the ovine and the bovine strains of F. hepatica appears to be the same.