The bacteria M. synoviae is a member of the mycoplasma genus. It causes disease in the joints, bones and respiratory system of birds. It is found throughout the world and infection may be referred to as Infectious Synovitis, Avian Mycoplasmosis, Infectious Sinusitis and Mycoplasma Arthritis. It is of economic importance because infection can cause a drop in egg production. The disease is most commonly seen in chickens, and transmission occurs both vertically and horizontally.