Campylobacter bilis, the second novel Campylobacter species isolated from chickens with Spotty Liver Disease, can cause the disease

Spotty Liver Disease (SLD) is a significant disease of commercial layer hens. It can cause up to 10 % flock mortalities and reduce egg production by 25 %. Campylobacter hepaticus has been identified as the main cause of the disease, although it also appears that predisposing factors, such as some form of stress, may increase the likelihood of clinical disease occurring. Recently, a newly identified species, Campylobacter bilis, was isolated from bile samples of clinical SLD affected chickens. To investigate the pathogenic potential of C. bilis two independent isolates were used in infection trials of layer hens. Within 6 days of oral challenge birds developed typical SLD liver lesions, demonstrating that both strains induced SLD. C. bilis could be recovered from all the challenged birds that developed SLD. Thus, each of the steps in Koch's postulates have been fulfilled, confirming that C. bilis is an additional cause of SLD. A PCR method was developed which can specifically detect C. bilis from samples with complex microbiota. The identification of this newly discovered Campylobacter species as a second cause of SLD and the provision of a rapid method to detect the SLD causing bacterium will help with SLD vaccine development and epidemiology, thus assisting in the control of this important disease of poultry.