Mycoplasma meleagridis (MM) is the cause of egg-transmitted disease of turkeys in which the primary lesion is an airsacculitis in the progeny. Other manifestations include decreased hatchability, skeletal abnormalities and poor growth performance. The organism is a specific pathogen of turkeys. MM is distributed worldwide, and the incidence of MM-associated airsacculitis is very high (20–65%) in naturally infected cull poults.