Abstract: In November 2011, an avian disease was occurred in a local chicken farm in Shandong province characterized by obviously swell in and around the eyelid and the subocular sinus. One bacterial strain was isolated from the infected chickens, and the bacterial strain was initially identified as Haemophilus paragallinarum (Hpg) based on the following methods,clinical symptoms of the infected chicken, isolation and culture of bacterial strain,morphological observation, catalase test, gram stain, animal regression test,vaccination and bacterial challenge experiments and PCR. In addition, the horizontal transmission test of the isolated bacterial strain suggested that the horizontal transmission of Hpg and repeated outbreak of IC in this farm were much related to the stocking density. Finally,the isolated bacterial strain was sent to R&D center of CEVA in Hungary for further identification, and the strain obtained from the chicken farm in Shandong province was serotype A Hpg(Shangdong strain).Besides,through the homologous comparison and analysis with the Genbank published Hpg gene sequence, it indicateed that homology of nucleotide sequence between our isolated strain and the reference strain could reach 99.0%.

Key words: Haemophilus paragallinarum; Shandong strain; isolation; identification