Pathogenic Studies Of Ducks Infected With Metorchis Taiwanensis

The paper reported the studies on the pathogenicity of ducks experimentally infected with Metorchis taiwanensis metacercariae. 70 one-week-old broiler ducks were divided into three groups at random. Each bird in group I group II was orally inoculated with 800. 300 infective M taiwanensis metacercariae respectively, and group III was used for uninfected control experiment. Clinical symptom, changes of body weight and blood, macroscopical pathology were observed regularly; histopathological changes were carefully examined by light microscope; livers and gallbladders were also observed by transmission electron microscope and scanning electron microscope. In addition, the possibility of cancerogenic change in liver and gallbladder caused by metorchiasis was studied too. As a result, infected groups showed clinic symptoms such as diarrhea on the 3rd day after infection, and some of group I began to die on the 5th day. The clinic symptom of the infected duck was characterized by the white beak, which appeared one week later. Haematologically, erythrocytes and hemoglobin dropped; eosinophils raised; the change of serum turbid demonstrated the hypohepatia. Compared with the control group, the infected groups showed reduced growth and the body weight was different significantly (P<0.01 or 39 P<0.05). Hemorrhage of blood in enlarged liver, thickened bile duct, incrassation of gallbladder wall, concentrated bile and splenomegalia were typical characteristics in systemic necropsy at early stage. The early histopathological changes were mainly cholecystitis, cholangitis, pericholangitis, interstitial hepatitis, focal necrosis of liver, acute splenitis. Cirrhosis, proliferation of bile canaliculi and connective tissue, cholestasis took palce at late stage. Results of scanning showed that mucosal surface of gallbladder was badly damaged, and that the function of the epithilioid cellls was lost; fibroblastic proliferation on the wall of large bile tract was found too. Necrobiosis of hepatocytes was the distinctive ultrastructural pathological change at early stage. The mitochondria swelled with distegration and lyses of the cristaes, and the glycogen dcreased in the liver cell. Enlargement of hepatic sinusoid was obvious 1, which contained eosinophils, and inflammatory cells. At late stage, the karyotheca of liver cell was obscure, and there were lots of bile-salt crystalloids in the nucleolus. The bile canaliculus proliferated in which the bile stagnated, so the bile embolus was common. Hyperplasic fibroblasts and fascicules were seen around the liver cells. Through the examination of the duck liver at tenninal stage, it can be concluded that the disease may conduce to the adenocarcinoma of bile bladder and the primary carcinoma of liver.