Abstract
Single experimental infections of 8 to 12 week old calves with 200 to 15,000 metacercariae are described. It is shown that as the level of metacercariae infection rises the numbers of fluke reaching and persisting in the bile ducts fall. In the higher infections the majority of the flukes are trapped and eliminated in the parenchyma and clinical disease does not develop. In lower infection levels the majority of the flukes reach the bile ducts and clinical disease develops.