Newcastle disease

Effects

Members of this virus family have a single stranded, linear, RNA. Severity of the disease is extremely variable from subclinical until high mortality depending on the strain of virus, species and age of bird, concurrent disease, and pre-existing immunity. Virulent strain of the Newcastle disease virus cause severe disease of the digestive, respiratory and/or nervous systems in particular in susceptible domestic poultry.

Transmission

In cage and aviary birds, and wild birds the outcome of the disease depends much more on the type of bird. A death rate of almost 100 percent can occur in unvaccinated poultry flocks. The disease is transmitted through infected birds' droppings and secretions from the nose, mouth, and eyes or indirect by exposure to materials contaminated with these secretions. The incubation period of the disease in poultry flocks ranges from 2 to 15 days.