Avian mycoplasmosis

Diseases caused by mycoplasmas—organisms intermediate between viruses and bacteria—common worldwide especially in large flocks; in chickens they cause chronic respiratory disease; in turkeys chiefly sinusitis and airsacculitis; some species cause arthritic lesions in chicks and poults, head swelling, conjunctival and infraorbital sinus inflammation; prevention relies on general biosecurity and establishing mycoplasma‑free flocks.