The Pathogenic Studies Of Riemerella Anatipestifer

The number of breeding duck has been dramatically increased around Weifang in recent years.The incidence of infections disease is also going up,especially RiemereUa anatipestifer infection characterized by cellulose pericardistis glissonitis pneumalocelatis,tryomatosis salpingitis and meningoen cephlitis.Riemerella anatipestifer infection is a contagious disease of domestic ducks,geese,turkeys and various other domestic and wild birds.It is a major disease confronting the duck industry all over the world,and it usually brings lots of economic losses to the duck industry because of high mortality and loss of weight.In this research,8 strains of RA were isolated from sick young ducks in Weifang.The 8 strains of RA were identified by bacteria isolation, biochemistry test,pathogenicity test,PCR and so on.So the 8 strains of RA were named CY1,SG2,QZ3,SG4,HT5,WC6,LQ7,FZ8 and by drug sensitive test WC6 was identified that it had the highist pathogenic.Rabbit was immunized by WC6 several times and the positive serotype was prepared. 4 strains of bacteria were identified as the 3 serotype as Riemerella anatipestifer by slide agglutination test by use of the positive serotype。And then,291samples of duck serotype were collected from several places in Weifang,the positive rate was 24.4 percent by side agglutination test by use of WC6 agglutination antifen.It was said that the 3 serotype was widely distributed in Weifang.Then WC6 was made bacteria liquid including 3×10~9CFU/ml bacteria and young ducks of ten days were immunized 0.2ml bacteria liquid by injcting web-footed.After that observing clinical symptoms and pathological changes, collecting thymus,bursal and spleen,measuring the index of immune organs and making the pathelodical section.It is showed that the index of spleen was higer than the control group and the difference was significant.The indexs of bursal and thymus had insignificant difference.The bursals and spleens had obvious Pathological changes,and the thymus had light Pathological changes.WC6 were cultivated and made to HCHO inactivated vaccines and aluminum hydroxide vaccines.The-5-day-old ducks were separated into 4 groups and the 3 groups as experimental groups were immunized with these two vaccines.After 4,7,14,21,28,35days of the first immunization,the groups were immunized once again with the same RA strain.The protection rates were 40%and80%on 4th day,and reach a peak of 100%on 14th day till 21th day,then all droped to 60%and 80%on 35th day.On 7th day of the second vaccination with HCHO inactivated vaccines the protection rate reached 100%till the 21th then droped to 80%the last.