Exotic Newcastle Disease (END) is a highly contagious avian disease, that is caused by a virus and characterized by rapid spread and high mortality rates. END is so virulent that many birds die without showing any clinical signs. A death rate of almost 100 percent can occur among unvaccinated flocks. Even vaccinated birds are susceptible. The mortality rate in vaccinated commercial layer flocks may double or triple the normal death rate.
The disease does not pose any significant risk to human health. Poultry and egg products are safe to consume. In rare cases, humans have contracted END from infected birds, typically resulting in conjunctivitis with a rapid recovery. When infection is seen in humans, it is most common in laboratory workers, vaccinating crews, and rarely, in poultry handlers.
Exotic Newcastle affects the respiratory, nervous, and digestive systems. The incubation period for the disease ranges from 2 to 15 days. An infected bird may exhibit the following signs:
END is spread primarily through direct contact with the bodily fluids of infected birds, including the droppings and secretions from the nose, mouth, and eyes. The virus spreads rapidly among birds kept in confinement.
The disease is spread easily by mechanical means; the virus can be picked up on shoes and clothing and carried from an infected flock to a healthy one. The disease is often spread by vaccination and debeaking crews, manure haulers, rendering-truck drivers, feed delivery personnel, poultry buyers, egg service people, and poultry farm owners and employees.
The END 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.
The only way to eradicate exotic Newcastle from commercial poultry is by rapidly destroying infected flocks, conducting surveillance, and imposing strict quarantine. Poultry producers of all size and scale should practice biosecurity in order to prevent the introduction of the disease to their flocks.