Quail bronchitis is a contagious, highly fatal disease in young bobwhite quail. The virus causing this disease also infects chickens and turkey. This agent is also known as a CELO (Chick Embryo Lethal Organism) virus. It has been isolated from chicken eggs but does not produce a recognizable disease in chickens or turkeys. This agent may play a part in respiratory diseases and in infertility problems, but its importance must be established by additional research. It is important because it is one of the agents that may be isolated from birds with respiratory symptoms and is difficult to separate from other agents such as infectious bronchitis virus.