Studies on Epidemiology Of Infectious Laryngeotracheitis In Poultry in Egypt

Testing 1755 serum samples from broiler, layer and breeder flocks reared in 4 provinces in Egypt andscreened by percentage of positive reactors varied from 33.3 to 75for broilers and 44 to 66 for layers. The highest percen- tage of positive reactors 64 percent ) was detected inSharkia, while the least 41 percent was in Alexandria.Trials for ILT virus isolation was successfull in one out of four flocks showing severe respiratory signs.The isolated strain produced small whitish pock lesions on CAMs and characteristic inclusion bodies on histopath- ological examination and was positive when tested in AGPTagainst positive ILT serum.LSL, 4 weeks old chicks were vaccinated by the loca- lly available ILT occular vaccine at different intervalsbefore intratracheal challenge with a virulent strain showed a 57 , 95, 100, 95 percent protection on 2 nd , 4 ~, 7 th and 18 th days postvaccination respectively.Birds vaccinated simultaneously as well as 4 and 7 days postchallenge showed a lower levels of protection 50, 43 and 24 percent respectively.