Occurrence: Worldwide.   Species affected: All.   Age affected: All.

Causes: Mycoplasma gallisepticum, M. gallinarum, M. synoviae, M. meleagridis, M. iowae and/or TRT. Spread through egg and contact with infected litter, feed or water. Aerosol spread also occurs.

Effects: Signs include foaming of the eye, conjunctivitis, coughing, tail bobbing when breathing, emaciation, rales, nasal discharge, sneezes, open mouthed breathing, poor growth, decreased feed consumption, lowered egg production and poor shell quality.

All species of bird of all ages are susceptible to chronic Mycoplasma infection. A number of different agents are involved in the aetiology of this disease. These include M. synoviae (MS) or M. gallisepticum (MG) in chickens, M. meleagridis (MM) and M. iowae (MI) in turkeys. M. synoviae (MS) is usually less pathogenic. Synergistic effects with E. coli and/or NDV and/or IBV vaccine viruses may occur. ILT can also be involved.

It is spread through eggs and contact with infected litter, feed or water. It is also transmitted by people, vehicles etc. E. coli is a secondary invader of mycoplasma-infected birds.

Aerosol spread occurs. Severe ND, IBV or ILT reactions may occur after vaccination, especially if given by spray to chicks previously infected with mycoplasma or E. coli.

E. coli is a normal contaminant of the intestine, but is a primary pathogen in the respiratory tract. Birds compromised by immunosuppression due to an early infection with IBD commonly develop CRD. It is a major cause of condemnation in the processing plant.

Signs include coughing, tail bobbing when breathing, emaciation, rales sneezing, open mouth breathing, poor growth, decreased feed consumption, lowered egg production and shell quality.

Yellow fibrin on the heart, liver and viscera organs, caseous air sacs, muscus in trachea and green livers can be seen.

Laboratory isolation and identification of E. coli or mycoplasma from lesions. Detection of mycoplasma colonies using fluorescent antibody test, recombinant probe and hybridisation or antigen capture ELISA.

Serology includes ELISA, plate agglutination and Haemagglutination-inhibition, (HI) testing of sera for antibodies against mycoplasma.

A cheesy exudate in the air sacs is a presumptive diagnosis.

Hatch stock free of mycoplasma infection. Use pelleted feed to kill E. coli. Vaccinate breeders against E. coli, MG, MS, NDV, IBV, ILT and infectious bursal disease (IBD) to prevent the disease.

Vaccinate progeny against ND, IB, ILT and IBD, hatch and place mycoplasma infected stock separate from mycoplasma negative stock to reduce the spread of the organism. Treat all mycoplasma positive flocks with antibiotics to reduce spread into eggs.

Medicate all mycoplasma-positive broilers for the first 7-10 days in the feed or water.

Effective drugs include tylosin, LS 50® and quinolones.

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