Epidemiological Investigation Of Newcastle Disease In XinYang

Newcastle disease (ND) is regarded worldwide as one of the most devastating diseases of poultry. Its causative agent, Newcastle disease virus(NDV), is classified as a member of the order Mononegavirales family,Paramyxovirinae subfamily, Paramyxovirinae genus rubulavirus. Because of the severe nature of the disease and the associated consequences, ND is included as an Office International des Epizooties (OIE) list A disease. In the past two decades, an intensive vaccination program against ND has been practiced in both large-scale poultry operations and village poultry farming. Disease outbreaks occur infrequently in some vaccinated flocks, however, infections of atypical Newcastle disease in the chicken flocks have been more and more frequently reported since the late 1990s.Even some chicken flocks with high antibody level can also suffer ND. Some scholar think that the emergence of new genotypes or sub genotypes could be responsible for ND outbreak in vaccinated flocks. Especially when the emergence of variant NDV of goose origin was found, people are more and more interest in mechanism of the atypical Newcastle disease caused by virulent strain. To investigate the prevalence station, its distribution, occurrence,spread approach in Xinyang, to further research its variation laws. this thesis provide an consult thereunder to effectively establish a prevention program on this disease.One pair of primers were designed according to F gene sequences of NDV published in GenBank. a 712 bp was amplified to establish a RT-PCR assay, were used to detect NDV, IBDV, IBV and negative control. The results showed that except for NDV,other detect results are negative; RNA was extracted from 250μL NDV chicken embryo virus, be diluted 10-1-10-8, a visible objective strip can be amplified still; The same result can be gained in numeral repeated tests.This indicated that the established nested PCR assay has the virtues of stronger speciation, higher sensitivity and well stability. The suspected samples were tested useing this methods in all 10 regions. The results showed that the positive rate is 27.9%..The results showed that the newcastle disease is universal existence in Xinyang. the highest positive rate was 36.0% in Pingqiao,the lowest positive rate was 15.7% in Shangcheng. The highest infection rate was 42.3% of new roman, the lowest infection rate was 13.3% of gu-shi chickens. The highest infection rate were the chicks. The highest infection season was autumn and the lowest infection season was winter.The positive rate in the regions with many and small-scale pig farms was relative high.The NDV antibody was unqualified in most pathogenesis chicken farms.In summary, in this experiment, a RT-PCR detection method was established and clinicaled application. This study provided an consult thereunder to effectively establish a prevention program on laws, paved the way of the healthy development of swine industry in this in area.