Exotic Newcastle Disease Signs and Symptoms
A list of clinical signs the animal may or may not display.
Exotic Newcastle disease (END) is a contagious and fatal viral disease affecting all species of birds. Previously known as velogenic viscerotropic Newcastle disease (VVND), END is probably one of the most infectious diseases of poultry in the world. END is so virulent that many birds die without showing any clinical signs. A death rate of almost 100 percent can occur in unvaccinated poultry flocks. END can infect and cause death even in vaccinated poultry.
END 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:
- Respiratory: sneezing, gasping for air, nasal discharge, coughing. Straw colored exudate may flow from the mouth or nasal openings. Respiratory distress may vary from mild to severe.
- Digestive: greenish, watery diarrhea
- Nervous: depression, muscular tremors, drooping wings, twisting of head and neck, circling, complete paralysis
- Reduction in or complete loss of egg production
- Swelling of the tissues around the eyes, especially of the lower eyelid
- Swelling in the neck
- Sudden death
There may be considerable variation in the severity of clinical signs, depending on species, age, vaccination, and natural resistance of the birds, as well as the virulence of the END strain. Most species demonstrate a period of depression, diarrhea, and loss of appetite. Clinical signs are more pronounced in susceptible chickens.
Clinical signs in turkeys and pet birds are usually mild. Torticollis, paralyzed wings and/or legs are commonly seen 10-20 days following onset of clinical signs.
Hemorrhage may be seen throughout the G.I. tract. These hemorrhagic areas tend to ulcerate and then became areas of necrosis as the disease progresses. These areas are most commonly seen at the junction of the esophagus and proventriculus, Peyer's patches, and cecal tonsils. The tracheal lesions are usually hemorrhagic without free blood in the lumen of the trachea.
Postmortem examinations of the pet birds many times fail to exhibit any of these lesions or are not as pronounced as those seen in chickens.