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Pathogen Page

Mycoplasma gallisepticum

I. General Information

1. NCBI Taxonomy ID:

2096

2. Disease:

Chronic respiratory disease

3. Introduction

Mycoplasma gallisepticum (MG) is a bacterium belonging to the class Mollicutes and the family Mycoplasma. 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. 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. Symptoms 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 (Wiki: Mycoplasma gallisepticum).

4. Microbial Pathogenesis

The epithelium of the upper air passages is most susceptible to infection; however, in severe, acute disease the infection is also found in the lower respiratory tract. There is a marked interaction between respiratory viruses, Escherichia coli , and M. gallisepticum in the pathogenesis of chronic respiratory disease. Once infected, birds remain carriers for life (Merck Vet Manual: M. gallisepticum).

5. Host Ranges and Animal Models

M. gallisepticum infection is commonly designated as chronic respiratory disease in chickens and as infectious sinusitis in turkeys. Infection may also be seen in pheasants, chukar partridges, and peafowl. Infection in pigeons, quail, ducks, geese, and psittacine birds should be considered. Passerine-type birds are quite resistant, although M. gallisepticum is the major cause of natural outbreaks of conjunctivitis in wild house finches (Carpodacus mexicanus) in the eastern USA (Merck Vet Manual: M. gallisepticum).

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