Comparative Pathological Studies on Infected And Vaccinated Chickens With Infectious Laryngotracheitis

This study was done to evaluate IL T infection among different breed in Sharkia, Dakahlia and Gharbia governorates during the period from December 2001 to February 2005 beside studying pathogenicity of field isolate in Native breed (Saso). The majority ofinvestigated outbreaks characterized by mild to severe typical signs and lesions, represented by coughing, sneezing, gasping, rales, dyspnea, extension of head and neck in addition to blood expectoration of tracheal origin with mucus and conjunctivitis. Tform of mucoid exudate to blood clot. Microscopically, histopathological changes obtained were consider diagnostic to ILTV consisting of syncytial giant cells containing eosinophilic intranuclear inclusion (1Nl) bodies in the epithelial lining of tracheashemorrhage and round cells infiltrations. The course of the disease was 7-13 days. All outbreaks were confirmed by isolation of the virus on chorioallantoi c membrane (CAMs) of 10-11 day old embryonated