INFLUENCE OF METHOD OF INFECTION ON PATHOGENESIS OF INFECTIOUS LARYNGOTRACHEITIS

The distribution of ILT virus in 12 to 18 week old, minimal disease chickens was described following administration of the same virus strain by aerosol, the intranasal drop and the intratracheal swab methods respectively. Virus distribution was also determined in the birds infected by contact with chickens infected by an aerosol. The birds infected by the aerosol method developed a severe form of the disease, suffered a high mortality rate and there were extensive lesions throughout the respiratory tract. Virus was present throughout the respiratory tract and in some other organs. The birds infected by the intranasal route failed to show clinical symptoms, and virus and lesions were mainly confined to the nasal cavity. The birds infected by the intratracheal swab method developed mild respiratory symptoms and there was no mortality. Virus and lesions were mainly confined to the trachea and there was little involvement of the lungs and air sacs. The disease in the incontact infected birds resembled that in the birds infected by the intratracheal swab method. There was no mortality. © 1969.