A Survery Of The Epidemiology And Prevention Of Chicken ND In Shangdong Province

Thirty-eight virus strains were isolated from affected chicks in Weifang, Qingdao, Yantai, Binzhou, Zibo, Dezhou, Heze, Linyi of Shangdong province using specific pathogen free (SPF) chick embryos These isolates are able to agglutinate chick red blood cell. Thirty-two virus strains of them were characterized as Newcastle disease virus (NDV) by hemagglutination (HA) /hemagglutination-inhibition (HI) test. The biological characteristics of these viruses were determined by measuring the mean death time of chick embryos (MDT) , the intracerebral pathogenicity index in day-old chicks (ICPI) and the intravenous pathgenicity index in 6-week-old chickens (IVPI) at the virulence of NDV. The results indicated that these isolates of Newcastle disease virus were high virulent Newcastle disease virus. 30-day-old unimmunized chicks were inoculated with these isolates of Newcastle disease virus . As a result, all the tested chick showed a 100% morbidity and a 70%~ 100% mortality respectively.The epidemiological results showed that Newcastle disease outbroks in Weifang, Qingdao, Yantai, Binzhou, Zibo, Dezhou, Heze, Linyi of Shangdong province. Newcastle disease could infect different ages and species chick in all seasons, but it was most popular in winter and in 20-40 or 180-260 days old chicks, the younger the chicks were, the higher mortality rates was; the rates to produce eggs of the chicks usually redudcd as 20%~50% , the mortality rates of adult chicks was0.1%-5%.The causes of Newcastle disease outbreaking in some areas of Shangdong province were analysed and a rule of biosecurity against it were made. The rule was applied in 20 farms where Newcastle disease have been found before. The results indicated that the rule was applicable. The reduction rates was 81.8%.