Newcastle disease has been reported in wild birds in Canada and the USA, and recently has been responsible for Cormorant die-offs. The natural reservoir is wild and domesticated birds. Exotic Newcastle affects the respiratory, nervous, and digestive systems. The incubation period for the disease ranges from 2 to 15 days. Swelling of the tissues around the eyes and in the neck Sudden death Increased death loss in a flock.
Transmission is by inhalation of infectious aerosols.
Intensive conditions favour spread by contact, on inanimate objects and airborne between poultry houses. Human infections occur mainly amongst laboratory workers and those who work with infected chickens or who give live vaccine, especially by aerosol. The exotic Newcastle virus can survive for several weeks in a warm and humid environment on birds' feathers, manure, and other materials. It can survive indefinitely in frozen material. However, the virus is destroyed rapidly by dehydration and by the ultraviolet rays in sunlight.