THE EFFECTS OF SUBCLINICAL FASCIOLIASIS ON HEPATIC SECRETORY FUNCTIONIN SHEEP

The effects of subclinical fasciolosis at various stages of its develo pment on bile flow and bile acid secretion and on the hepatobiliary tr ansport of bilirubin were investigated in experimentally infected shee p. Bile flow was significantly reduced by weeks 6-14 postinfection. Th is was accompanied by a decrease in bile acid secretion by weeks 6-8. Serum AST and GLDH activities and serum bile acid concentration were s ignificantly elevated from weeks 6 to 14. Total serum bilirubin was ma ximally increased at 6 weeks postinfection and remained elevated at we eks 8 and 14. Increases corresponded to both unconjugated and conjugat ed fractions, although the conjugated/total bilirubin ratio was enhanc ed in all infected animals. Biliary bilirubin secretion declined from weeks 6 to 14. No alteration was detected in either uridine diphosphat e (UDP)-glucuronosyltransferase activity, cytochrome P-450 concentrati on, or hematological markers of hemolysis. This study shows that the m igration of immature flukes in the course of ovine fasciolosis causes a cholestatic phenomenon responsible for changes in serum and biliary bilirubin levels.