Epidemiological Investigation Of Duck Tembusu Disease In Shandong Area

Since April 2010,a new disease which can cause the decline of duck egg production and the intake of food has occurred in China.Later,it was determined that the disease was caused by duck Tanbusu virus(DTMUV).The disease spread rapidly and broke out in a wide range.The disease was firstly found in Zhejiang,and then quickly spread to Fujian,Guangdong,Guangxi,Anhui,Jiangxi,Jiangsu,Henan,Hebei,Shandong and Beijing.The disease is mainly infected with ducks,and the goose is also reported to have infection.The spread of this disease in Shandong province is very fast.According to our laboratory records of the earliest cases from the Yucheng,pingyuan,and other places in Dezhou,and then all kinds of ducks in Jining,Tai'an,Heze,Binzhou and other places have been ill.At present,the disease is still widely prevalent,it is a serious threat to the duck industry in our country and bringing great economic loss,so the domestic scholars and producers are still very concerned about this disease.Therefore,to understand the epidemic situation of DTMUV in Shandong and the variation of virus gene,to grasp the regularity,to observe clinical symptoms and pathological changes of the infected ducks,have important theoretical significance and practical application value for the diagnosis and control of the disease and the in-depth study of the DTMUV.3865 blood samples were collected from the duck group of different varieties with injecting DTMUV vaccine,and the antibody of duck Tanbusu virus was detected by blocking ELISA.According to that,we can know Since Septembe 2016,commercial duck,reserve duck and commodity duck group in different regions had been infected by DTMUV.The highest rate of infection the laying duck group,the positive rate is 55.5%,followed by the positive rate of duck group is 19.5%,the lowest positive rate is the reserve duck group,the positive rate is 15.5%.The RT-PCR rapid detection method of duck Tanbusu virus(RT-PCR)was used in the laboratory to detect 270 samples of clinically suspected cases from all parts of Shandong.The results showed that 36 samples were positive for DTMUV,and the positive rate was 13.3%.The characteristics of the current clinical cases are intracardiac and epicardialhemorrhage,splenic mottle necrosis,follicular liquefaction and rupture,follicular membrane congestion and bleeding,and gray and white oval swelling in the central mucosa of the central ileum.The pathological features of histopathological diagnosis are viral encephalitis,endocardial hemorrhage,infiltration of lymphocytes,necrosis of spleen lymphocytes in varying degrees,degeneration and necrosis of liver cells and infiltration of lymphocytes.The genetic distance between the strain and the current DTMUV strain is less than 3.5%.,and the genetic distance from Sitiawan virus and Denguevirus-AB214882.1 was far away,and it was in another evolutionary branch.There was no significant regional,temporal and host difference betweenthe tested strains..The homology similarity of E gene between selected positive samples is very high,and the homology similarity with other published DTMUV is also up to 99.5%.