Concurrent infection of Avibacterium paragalinarum and Escherichia coli in layers with Swollen Head Syndrom (SHS) in Isfahan province

To investigating the role of Avibacterium paragalinarum (AP) in the development of Swollen head syndrome (SHS) in commercial and traditional layers in Isfahan province, 23 laying hen farms with signs of head swelling and mortality were sampled from the suborbital sinus. In addition, swabs were prepared from 20 traditional and commercial laying hen farms with respiratory symptoms and SHS. Samples were cultured on specific media for isolation Escherichia coli (E. coli) and AP and approved by biochemical examination. After genome extraction, AP was detected with specific primers. Microbiological results showed that out of 23 samples, 14 samples (60.86%) were infected with AP and 21 samples (91.3%) were infected with E. coli. The results of direct detection of AP in suborbital sinus swabs that prepared from 23 dead laying hens with coryza symptoms showed the amplification of 500 bp fragment in 19 samples of suborbital sinus swabs (82.6%). Also, the rate of infection in live birds was less than the dead hens. It seems that the sampling site can play role in the rate of infection and possibly the occurrence of false negatives. Therefore, due to the high frequency of AP infection in hens with SHS, it seems that a regular and public vaccination program should be applied to control Avibacterium paragalinarum in laying hens.