PRELIMINARY EPIDEMIOLOGIC INVESTIGATION AND PATHOLOGICAL OBSERVATION OF A SUSPECTED DUCK VIRAL DISEASE IN SHANDONG PROVICE

Since August 2010,a suspected duck new virus disease has been quickly epidemic in Shandong province,causing enormous losses in duck industry.In order to understand the prevalence of the disease in Shandong,the clinical diagnosis symptom of typical cases and necropsy lesions were studied in detail.In addition,the histopathology of sick duck's tissues and organs were observed.The results showed that the disease all occurred in commercial irou,meat breeders and commercial ducks with 100% incidence rate in some areas.The disease was characterized by wide popularity,fast spreading,acute onset,ineffective medical therapy,longer duration up to 2-3 weeks,and lower mortality with 6%-10%;The clinical lesions were manifested by fever,diarrhea,rapid decline in feed intake,egg production seriously decreasing and neurological symptoms;The main necropsy lesions were characterized by oval swelling in the center of ileal mucosa,focal necrosis in spleen,atrophy in ovarian follicle and oviduct,denaturalization and swelling or bleeding in liver and bleeding on the endocardium and epicardium of the heart;histopathological changes mainly showed acute catarrhal inflammation in digestive tract,significant hyperplasia in local lymphatic tissue,denaturalization necrosis or hemorrhage in heart,liver,kidney and pancreas,necrosis in lymphoid tissue of spleen,infectious bursa and mild viral encephalitis.