Studies On Epidemiology And Characteristics Of The Pathogen Of "New Duck Plague

New Duck Plague was an acutely and septicemicly infectious disease with the similar symptoms and changes of pathology to Duck Plague. But there had no preventive effect when vaccinated with vaccine of DPV, and no therapy with anti-serum of DPV after infected the disease. Both morbidity and mortality were so high that it did harm to duck industry seriously. In order to control the disease and promote the development of duck industry, isolation and identification and some characteristics were carried on, further more, an investigation of epidemiology and clinical pathology was also studied. The study was compose of two sections: Part Ⅰ: Investigation on epidemiology and studies on pathology of "New Duck Plague" In order to acquire some basic prevailing characteristics of the disease, a systematic investigation on epidemiology and raiser's consultation was processed , including the variety , age , morbility , mortality and management ,etc. .We found that meat ducks were infected easily, especially cherry-valley ducks, the infected age was less one month old. Morbility and mortality could be up to 70%～100% and 50%～60%. We also found that the clinical symptom and changes of necropsy were similar to Duck Plague, it showed that all organs had extensive bleeding. Further more, through the examination of histopathology of the natural ill ducks after 24h' fix with Formalin, in the surfaces of liver and spleen, necrosis was found seriously, and the epithelia of renal tubules were degenerative and swelling,and the structure of small intestinal membrane disappeared and intestinal villus were exfoliate and some seriously lymphoid infiltrition . The lung and the pancreas had bleeding and necosises in different degree too. Part Ⅱ: Isolation and identification of pathogen of "New Duck Plague" A isolation viral particle with 80～200nm in diameter was gained from the typical dead ducks . The results of series of tests showed that the virus was sensitive to acid (PH 3.0),alkali (PH 11),heat(56℃), chloroform and aether .Many spherical particles with envelope and 80～200nm in diameter were scanned by electron microscope. Medicine restraining test(5- Bromo－Deoxy Uridine Bud R) showed that its nucleic acid is DNA. The mortalities of emthryonated poultry eggs including Cherry-valley duck embryo,Muscovy duck embryo,Shanma duck embryo ,Peking duck embryo and SPF chicken embryo inoculated with it were 100%,80%,14%,20% and 0%, respectively . It had no hemagglutination activity and no serological correlations with Duck Hepatitis virus typeⅠ,muscovy duckling parvovirus and gosling poorvovirus , while it had part correlation with Duck Plague Virus . It was categorized into herpesciridae and named tentatively as "New Duck Plague"Virus because of no treatment effect with vaccine and anti－serum of DPV..