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 newly defined genus Avulavirus in the family of Paramyxoviridae. 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 ...