Mycoplasma gallisepticum (MG) is the causative agent of chronic respiratory disease (CRD) in chickens, and infectious sinusitis in turkeys, chickens, game birds, pigeons, and passerine birds of all ages. MG is transmitted through the eggs of carrier hens. Even if most commercial flocks are MG-free, MG is the most economically significant Mycoplasma pathogen of poultry. MG-infected flocks show reduced feed efficiency, and decreased growth.
Mycoplasma synoviae (MS) causes respiratory tract disease and synovitis in chicken and turkeys. While many bird species may be affected by the disease, chickens are most susceptible. Infection occurs worldwide. MS infection leads to economic losses in commercial poultry flocks, reducing production, raising food conversion rates, and downgrading the quality of poultry carcasses. MS infection may also lead to reduced egg production and a lowered rate of viable hatching chicks.