Avian Viral diseases 1-Avian Paramyxoviruses Newcastle Disease (ND) It is acute viral disease of chickens, turkeys, pigeons, doves, pheasants and psittacines. Etiology: avian paramyxovirus-1, isolates vary greatly in pathogenicity to chickens Lentogenic: mild or inapparent (asymptomatic) infection in chickens Mesogenic: cause disease and mortality in young chickens Velogenic (viscerotropic and neurotropic): lethal for all ages chickens Clinical signs -Vary with strain, respiratory, digestive, ocular, neurological, sudden death -In mature chickens, egg production and quality problems (mesogenic strain)
Lesions In chickens: The disease has 3 forms: 1-Respiratory Form: it characterized by -Catarrhal tracheitis, pneumonia and conjunctivitis. -Petechial hemorrhages on the heart and abdominal fat.