A Survery On The Epidemiology Of DVH And Application Of Prevention And Control In Weifang Shandong Province

Forty-two virus strains were isolated from affected ducks in Changyi,Shouguang,Changle,Linqu,Anqiu,Weicheng,Hanting,Kuiwen,Qingzhou,Gaomi,Zhuchengof Weifang using specific pathogen free(SPF) chick embryos. Thirty-nine virus strains ofthem were characterized as Duck Hepatitis Virus(DHV) by chick embryos neutralizationtest and serum protection test of young duck. ELD₅₀of these viruses is from 10^-5.9 to 10^-5.3and the average is 10^-5.6. 1-day-old unimmuized ducks were inoculated with these isolates ofDHV. As a result,all the tested ducks showed a 100ï¼…(10/10)incidence and a 70ï¼…-100ï¼…(7/10-10/10)mortality respectively.The epidemiological results showed that DVH often outbreaks in Changyi,Shouguang,Changle,Linqu,Anqiu,Weicheng,Hanting,Kuiwen,Qingzhou,Gaomi,Zhucheng of Weifang. DVH could infect different ages duck in all seasons, but it mostpopular in spring or winter and in 4-21 days old ducks. The younger the ducks were,theincidence and the mortality were; the mortality of 4-7 days old ducks was 75ï¼…(15450/20600), the incidence of 4-7 days old ducks was 74.6ï¼…(20600/27600).The causes of DVH outbreaking in some areas of Weifang in Shangdong provincewere anaiysed and a rule of biosecurity against it were made, for example rebuilding the oldfield and strengthening management of sanitation and ameliorating the project of immunity.The rule was applied in 20 farms where DVH have been found before.The results indicatedthat the rule was applicable and the reduction was 73.3ï¼…(22/30), The death rate reduced,The medicine cost reduced. Therefore,the synthetic rule of biosecurity has application value.