| This paper reports the morphology, life cycle, biology, pathogenicity and molecular geneticsof Amphimerus anatis.1. Life cycleAt water temperature of 17 -23 , eggs exposured to the snail host, Bithynia fuchsianus, the miracidia of A. anatis hatched from eggs and developed into mature sporocyts in 40 days. It was found that the redia matured and mature cercaria emerged from its snail host in 60 days after eggs eaten by snails. Pseudorasbora parua, Carassius auratus, Cyprinus carpio, Rhodeus sinensis, Oryzias latipes, Ctenogobius giurinus, Monopterus albus, Misgurnus anguillicandatus and Rana japonica japonica, Rana guy Ho, Bufo bufo gargurizans,vere proved to be the second intermediate hosts with infection experinment. Cysts did not possess the power of infectivity until they developed in the fish for 30 days. When they were fed to ducklings, they developed to adults in the bile duct in 20 days.2. Biology of CercariaCercaria of Amphimerus anatis begin to emerge from snail host when water temperature up to 20 , and stop coming out from water snail while water temperature drop to 15 .Most of cercariae emerged at 7-19 0 clock in a day. It was proved that the main factors affected on emerging of cercaria was temperature. The survival of cercaria has close relation to temperature and water Ph.3.Studies on redia, cercaria, young and adult of Amphimerus anatis by SEMThe tegumental surface of redia was spongelike projection. There were lamellae, small holes and spines on the dorsal side of cercaria. Spines were also found on the oral sucker and ventral sucker of ceraria. In 7d, 14d, 21d, 28d and 36d of Amphimerus anatis, their tegumental surface were nest and spongelike structure and free of spine. Numerous small holes could be seen on their tegumental surface. Papillae were only found around the ventral sucker.4. Pathogenicity on duck.Each one - week-old broiler ducks was orally inoculated with 20 infective Amphimerus anatis metacercariae. 1-2 weeks later, infected duck showed clinic symptoms such as diarrhea. Haematologically, erythrocytes and hemoglobin dropped, eosinophils raised. Compared with the uninfected control experinment, the infected group showed reduced growth and body weight. Hemorrhage of blood in enlarged liver, histopathological changes were interstitial hepatitis and focal necrosis of liver. The mitochondria swelled with distegration and lyses of the cristaes, and the glycogen decreased in the liver cell. Hyperplasic fibroblasts and fascicules were seen around the liver cells.5. Analyze on Amphimerus anatis and Metorchis taxwanensis by RAPD2 species of trematodes in Opishorchiidae (Metorchis taiwanensis and Amphimerus anatis) were analyzed using random amplified polymorphic DNA technique (RAPD). 17 primers were screened from 40 random 10-mer primers,and a total of 152 DNA bands were amplified ,134 of which (about 88.16%) were polymophic bands with a mean 6.7 bands perprimer. The number of amplified bands by each primer ranged from 5 to 16 with size from 335 to 2460bp.Primer S465 amplified the greatest number of bands (16 bands), primer S477 amplified the least number of bands (5 bands). Similarity coefficient between Amphimerus anatis and Metorchis taiwanensi was 0.2188.6. Expelling Amphimerus anatis from duck by Praziquantel and Fenbendazole70 one-week-old ducklings were orally inoculated with 30 infective Amphimerus anatis metacercariae, 21 days later they were divided into 7 groups at random. Group I , group II and groupIII are given praziquantel at the dose of 10mg/kg. b. d, 20tng/kg. b. d, 30mg/kg. b. d respectively;while gronpIV, gronp V and gronpVI are given Fenbendazile at the dose of 10mg/kg . b. d 3, 20mg/kg. b. d 3, 30mg/kg. b. d 3. The result is that Amphimerus anatis can be expelled fully by praziqcmtes at the dose of 20mg/kg. w. b. d and 30mg /kg . w, b.d.
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