Bacterial infections of upper respiratory tract and its effect on mucosal immunity in chickens

In the present work, 400 swabs (200 nasal and 200 tracheal swabs)of 20 flkocks chickens with respiratory manifestations collected from EI-Sharkia and El-Dakahlia Governorates from different breeds withdifferent ages all over the year seasons. The specimens were examinedphenotypically and genotypic ally for the detection of the most importantvirulence genes of MG and E. coli ORT and Haemophilusparagallinarum.Concerning to the prevalence of single and mixed infection withMG, E. coli, ORT and Haemophilus paragallinarum in respiratorymanifested birds , the recorded results revealed that E. coli was highlydetected with a percentage of 19/20 flocks followed by ORT 6/20 thenMG 4/20 and Haemophilus paragallinarum 3/20 and discuss the mixedinfection between different microorganisms as Flock No. 6, 8, 15,20 aremixed between E. coli and MG also Flock No 4, 10,12,18,20 mixedbetween E. coli and ORT but Flock No 7, 17 are mixed between E. coliand Haemophilus paragallinarum, Flock No 13 are mixed infectionbetween ORT and Haemophilus paragallinarum flock No 20 the flock ismixed infection between E. coli, MG and ORT.In our study, none the flocks had single infection by either ORT orHaemophilus paragallinarum. The two microorganisms were persistenteither mixed with E. coli infection or mixed with each other (flock No13). E. coli infection is a predisposing factor playing an important role inthe severity and spread ofORT infection.