Comparative pathological study of hepatic changes induced by Fasciola gigantica and Gigantocotyle explanatum in Javanese thin-tailed sheep.

Pathological changes in the liver induced by Fasciola gigantica and Gigantocotyle explanatum were readily distinguishable from each other. Lesions associated with the migration of immature flukes through the parenchyma were a prominent feature of infection with Fasciola gigantica, whereas lesions induced by Gigantocotyle explanatum were confined to the large bile ducts. The size of the hepatic lesions increased during the course of infection with Fasciola gigantica and was associated with the formation of progressively larger areas of scar tissue in the parenchymal migration tracts as the flukes grew. This was also as a result of the progressively increasing cellular infiltration, proliferation of bile ductules and fibrosis which occurred in adjacent portal triads and interlobular septa. The absence of signs of migration through the hepatic parenchyma by Gigantocotyle explanatum, was regarded as evidence that these flukes gain entry to the bile ducts from the intestine via the common bile duct. In bile ducts infected with Fasciola gigantica there was more extensive desquamation of the epithelium, more intense mucosal infiltration with lymphoid cells and fewer eosinophils, less severe glandular hyperplasia, more free blood in the lumen and a thicker duct wall than in bile ducts infected with Gigantocotyle explanatum.