Newcastle disease

Newcastle disease

an infectious, highly contagious disease of chickens, turkeys and many wild birds, occasionally infecting humans, caused by avian paramyxovirus-1, in the genus Avulavirus. The disease causes very heavy losses in birds of all ages and frequently occurs as massive outbreaks. There are a number of clinical forms of the disease, including a nervous form characterized by tremor, opisthotonos and paralysis, and a mortality rate of 90%, an acute respiratory form with high mortality, up to 90% in chickens, an acute respiratory form without significant death losses, and a clinically inapparent form. The disease is also classified, on epidemiological grounds, into velogenic (peracute), mesogenic (acute) and lentogenic (subacute) forms, which are caused by viruses with a corresponding variation in virulence. Called also avian pneumoencephalitis.