Mycoplasma gallisepticum (MG) is a bacterium belonging to the class Mollicutes

Mollicutes

The Mollicutes are a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin mollis , and cutis . They are parasites of various animals and plants, living on or in the host's cells. Individuals are very small, typically only 0.2–0.3 μm in size...

 and the family Mycoplasmataceae

Mycoplasmataceae

The Mycoplasmataceae is a family of bacteria in the order Mycoplasmatales. This family comprises the species Mycoplasma and Ureaplasma.In 1967 the Order Mycoplasmatales was incorporated into the class Mollicutes....

. It 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.

Transmission

MG is transmitted through the eggs of carrier hens. Most commercial flocks are MG free, however, and the disease is most frequently introduced from carrier birds being brought into the flock. Stress is thought to lower the poults resistance to the disease, like in CRD.

Clinical signs

Clinical signs of infectious sinusitis for turkeys include watery eyes and nostrils and the area under the eye may be swollen. One may find airsacculitis with yellow exudates in the air sacs.
Chickens may have no outward symptoms or there may be a sticky nasal discharge, airsacculitis, coughing, difficult breathing, swelling of the face, sneezing, a foamy secretion in the eyes, and a drop in food consumption. Egg production may be far below normal and there may be a drop in body weight as well.

In CRD of young poultry, symptoms include rattling, sniffling, and sneezing. In older birds, conditions may go unnoticed. Worse conditions may exhibit nasal discharge or foamy secretion from the eyes. Lack of appetite, trouble breathing and a drop in egg production are also symptoms.The birds will also be stunned and unthrifty.

Treatment

There is no known full treatment/cure for infectious sinusitis but several antibiotics may help. These include macrolide

Macrolide

The macrolides are a group of drugs whose activity stems from the presence of a macrolide ring, a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered...

 antibiotics azithromycin, erythromycin and tylosin, and synthetic quinolone

Quinolone

The quinolones are a family of synthetic broad-spectrum antibiotics. The term quinolone refers to potent synthetic chemotherapeutic antibacterials....

antibiotics enrofloxacin and norfloxacin. These are given through food, water or injections. Especially tylosin gives good results in the feed.