Estimation of Newcastle Disease Prevalence in Scale Farms in 6 Cities of Anhui Province and Analysis on Relevant Risk Factors
In order to identify the infection status of Newcastle disease virus(NDV)and risk factors leading to the disease in Anhui Province,an cross-sectional study was carried out in the scale farms with an inventory of 3 000 to 10 000 chickens in six cities in combination with centralized surveillance and sampling in the fall of 2019. A total of 5 369 throat/cloacal swabs were randomly collected from 153 farms by two-stage sampling method. Meanwhile,a questionnaire investigation was conducted to analyze relevant risk factors. The results showed that the apparent prevalence and true prevalence were 11.1% and 11.7% respectively at the farm level. It was shown that,by monofactor analysis,the potential risk factors included“only cleaning feces once a month,sharing equipment and vehicles within the farms”,which was of statistical significance(P<0.05);and the risk of infection could be reduced by disinfecting vehicles and personnel when they were entering or leaving farms,separating clean channels from the dirty ones,disinfecting empty pens and cleaning the premises prior to disinfecting. It was shown by Logistic regression analysis that,the risk factors included“failure to separate clean and dirty channels and to disinfect vehicles and personnel in or out of farms”. As a conclusion,NDV was still prevalent in some farms in Anhui Province,and some suggestions were put forward,such as strengthening bio-security management in the farms,reasonably designing their layout,building a disinfection pool at the entrance,separating clean channels from the dirty ones,strictly disinfecting vehicles and personnel when they were entering or leaving farms,and developing detailed disinfection plan to practically improve the environment of the farms.