Newcastle Disease in Turkeys

Newcastle disease (ND), caused by avian paramyxovirus serotype 1 (APMV-1), is a viral disease of many poultry species characterized by respiratory manifestations followed by/or accompanied by nervous manifestations. ND is ranked as the major virus disease of poultry in many countries worldwide, and it is challenging to assess the prevalence of ND worldwide. It is a worldwide enzootic disease. Based on its pathogenicity, NDV is classified into five pathotypes: apathogenic, lentogenic, mesogenic, viscerotropic velogenic, and neurotropic velogenic. The velogenic strains are the most virulent and can cause 100% mortality in susceptible birds. Based on the complete genomic analysis, they are grouped into classes (Class I and II); the latter class is subdivided into at least 21 distinct genotypes. The presumptive diagnosis of NDV is based on the clinical signs and postmortem lesions and confirmed by isolation and identification. Isolation can be done by inoculating the suspected samples into the allantoic cavity of 9- to 11-day-old embryonated specific pathogen-free chicken eggs. The virus can be identified using the hemagglutination test, PCR, and the hemagglutination inhibition test using PMV-1-specific serum. The pathogenicity can be identified using the intracerebral pathogenicity index (ICPI), mean death time, intravenous pathogenicity index (IVPI), and sequence analysis of the cleavage site of F-protein. ND is a notifiable disease in several countries. The prevention of ND is based on good biosecurity and vaccination. Several vaccines are available, including live, inactivated, and recombinant vaccines.