Study On The Comprehensive Prevention And Control Measures Of Serotype Ⅰ Duck Viral Hepatitis In Shandong Province

Duck viral hepatitis(DVH) is a highly mortal disease and spreads rapidly in six-week-old ducklings.It is caused by duck hepatitis virus type I(DHV-1). The virus mainly infects the ducklings between two-day-old and three-week-old,but the adults have some resistance to the disease.The mortality rate is different from 15%to 95%in different ages.The duckling resisted the disease could not grow up any more.In recent years,the scientists of China have made great successes in the dianosis and prevention of DVH.The inactivated and activated vaccine of DVH have been making successfully and using widely in many areas,which have brought great economical benefits.But DVH often occurs at present and makes great harm to the commercial breedings.To find out the disease's reaction and epidomic feature,the epidemio[ogical investigation was made in 60 commercial farms of different areas in Shandong through clinical checking and laboratory checking. This study was divided into four parts.Partâ… :the epidemiologieal investigation of DHV-1,DPV,RA and E.coli in sick ducks in Shandong province.Tissue samples of 388 ducks suspected to infect DHV-1 were collected from different areas and these samples were detected for DHV-I.Duck plague virus(DPV),Riemerella anatipestifer(RA),Escherichia colibacterer(E.coli). The results indicated that 344 ducks were infected DHV,occupied the total's 88.6%.and only 163 ducks were infected DHV-1 alonely,occupied the total's 42%,the others were dual-infection or multi-infection of DHV,DPV,RA and E.coli,etc.Partâ…¡:Compared the toxic of isolates from different areasFrom the tissues of different areas,six isolates DHV-1 were gained by the neutralization test of duck embryo and the protected test of ducklings.The toxic of different isolates were compared by the 50%Duck Embryo Lethal dose(DELD₅₀),minimum dead time(MDT),intracerebral pathogenicity index (ICPI).The results indicated that the toxic of DHV-LQ was the highest,and the toxic of DHV-BX was the lowest. Partâ…¢:Development of multi-immune yelk antibody against DHVâ… .Six yelk antibody were developed with each isolate of different DHVâ… .By comparing nertralization titers and the protected test,the result showed the effect of the antibody made with the higher toxic isolates DHV-LQ,DHV-XT were better than other lower ones.When the nertualization titer was above 2⁹ the curative effect was good.Partâ…£:Study on the comprehensive prevention and control measures of DHVâ… .According to the results of the epidemiological investigation,the disease's reaction and epidomie feature were found out,the comprehensive prevention and control measures of DHVâ… have been made and gained obvious prevention and control effects.