Abstract

Infectious Laryngotracheitis (ILT) is a viral respiratory disease of poultry caused by Gallid herpesvirus 1 leading to severe economic losses. The aim of the current study was to isolate and identify ILT virus in suspected outbreaks of one broiler flock (farm 1) and three layer flocks (farms 2,3 and 4) located in Tripoli. Samples of trachea were collected and preserved in transport media for viral isolation and some were preserved in 10% neutral formalin for histopathology. Broiler and Layer flocks were serologically monitored and tested for the presence of antibodies by ELISA against ILTV at first days old and later at slaughter age for broilers and before the onset of production for layers in which total of 290 blood samples were collected from six poultry farms (3 broiler flocks and 3 layer flocks). Following isolation of the virus in fertile eggs, chorio-allantoic membrane (CAM) samples were confirmed by PCR and histopathology. The lesions seen on the CAMs were congestion, hemorrhages and pocks after 5 days post inoculation. Samples from farm 1 and 3 were positive whereas other farms were negative. Histopathology of CAMs revealed edema, congestion, haemorrhages, infiltration of heterophils and mononuclear cells, and presence of syncytial cells containing intranuclear inclusion bodies. The trachea revealed severe destruction and sloughing of the mucosa due to necrosis. The results of this study confirmed the circulation of ILTV in commercial poultry flocks and highlighted the need for more epidemiologic investigation of the disease in the whole country. The next step will be the phylogenetic analysis of the viral genome by sequencing

Keywords: ILT; Broilers; Layer; PCR; Virus isolation; Histopathology; ELISA