Symptoms
Possible symptoms of Newcastle disease in chickens include general depression, fever, oedema, diarrhea, hemorrhagic lesions in the digestive tract, respiratory problems, egg abnormalities, torticollis, and paralysis. The severity can vary greatly depending on the outbreak and the strain of virus, making diagnosis difficult. In a severe course, nearly all animals may perish. In humans, transient conjunctivitis may develop with eye redness, eye tearing, oedema, lymph node swelling, and bleeding in the eye. There are reports of rare generalized infection with chills, headache, and fever.
Cause
The cause of the symptoms is infection with Newcastle disease virus (NDV) of the paramyxovirus family. It is also known as avian paramyxovirus 1 (APMV-1). The RNA virus is highly contagious, transmitted from bird to bird, via aerosols and objects (e.g., shoes, surfaces), and spreads very rapidly through flocks. Transmission to humans occurs through direct contact with chickens. In addition to domestic chickens, other birds such as pigeons, ducks, geese, parrots, turkeys, guinea fowl, migratory birds, and wild birds can be infected and act as reservoirs or vectors. However, chickens are specifically susceptible. The name of the disease is derived from the outbreak in Newcastle upon Tyne in the United Kingdom in 1926.
Prevention
Vaccines are available for prevention. However, immunoprophylaxis is prohibited in many countries. To prevent transmission to humans, good hygiene, frequent hand washing, eye protection, and appropriate clothing are recommended. Do not rub eyes with your hands.
Treatment
Treatment is usually by culling the herds and hygienic measures. This may involve killing large numbers of animals, depending on the outbreak. For example, an outbreak in Italy between 1999 and 2000 claimed more than 13 million chicken lives.
