Abstract:

This study aimed to assess the risk of infection of Newcastle Disease Virus (NDV) infection in domestic poultry through migratory birds and to provide early warning for the occurrence of NDV. A scenario tree model was established in which a wild bird carrying NDV was introduced into a domestic poultry population. We used Anser indicus, Grus vipio and Larus brunnicephalus as the transmission medium. We also applied migratory bird NDV-positive rate, migratory bird survival, migratory bird appearance, migratory birds coming into contact with poultry, migratory birds coming into effective contact with poultry, immunization and vaccine protection efficiency as the main risk nodes. We conducted data collection and evaluation on the key risk nodes in the scenario tree, and conducted a quantitative analysis of the risk of NDV introduction through migratory birds with county-level administrative divisions as spatial units and months as time units. The results showed that in 2017 the main high-risk areas were in the southern coastal areas of China in January, February, November and December. Similar risk patterns were found in March, April, September and October, with the high-risk areas during these months mainly located in central and eastern China. From July to August, the relatively high-risk areas were in eastern China. These results suggest that the risk in the eastern and central regions of China is higher than in that in the western regions. Moreover, sensitivity analysis showed that vaccination was the most important factor for eliminating this NDV introduction risk by migratory birds. This study provides a technical solution for a risk-based disease surveillance and a theoretical basis for the prevention and control of emerging NDV outbreaks.

Key words: risk assessment, Newcastle disease, migratory bird, virus