Extracted From: A Pocket Guide to Poultry Health and Disease By Paul McMullin © 2004 Click Here to Order Your Copy

Introduction

A disease of turkeys characterised by respiratory and skeletal problems caused by Mycoplasma meleagridis. The organism has also been isolated from raptors, it occurs in most turkey-producing countries but is now much rarer in commercial stock. In adult birds though infection rates are high, morbidity may be minimal. Pathogenicity is quite variable. Mortality is low, though up to 25% of infected birds show lesions at slaughter.

Infection is via the conjunctiva or upper respiratory tract with an incubation period of 6-10 days. Transmission is venereal in breeders, with transovarian and then lateral spread in meat animals. Infected eggs result in widespread distribution of infection and increased risk of further vertical transmission. The infective agent does not survive well outside the bird. Predisposing factors include stress and viral respiratory infections.

Signs

• Reduced hatchability.
• Slow growth.
• Leg problems.
• Stunting.
• Mild respiratory problems.
• Crooked necks.
• Infected parents may be asymptomatic.

Post-mortem lesions

• Airsacculitis in infected pipped embryos and poults.
• Airsacculitis (rarely) seen in adult birds.

Diagnosis

Lesions, serology, isolation and identification of organism, demonstration of specific DNA (commercial kit available). Culture requires inoculation in mycoplasma-free embryos or, more commonly in Mycoplasma Broth followed by plating out on Mycoplasma Agar. Suspect colonies may be identified by immuno-fluorescence.

Serology: SAG used routinely - culture used to confirm. Differentiate from Mycoplasma gallisepticum, Mycoplasma synoviae, other respiratory viruses.

Treatment

Tylosin, spiramycin, tetracyclines, fluoroquinolones. Effort should be made to reduce dust and secondary infections.

Prevention

Eradication of this infection is also possible using similar techniques as for Mycoplasma gallisepticum. These are based on purchase of uninfected poults, all-in/all-out production, and biosecurity. Infected males are particularly prone to transmit infection and may warrant special attention. In some circumstances preventative medication of known infected flocks may be of benefit.

Vaccines are not normally used. Infected birds do develop some immunity. Birds infected from their parents seem to be immuno-tolerant and particularly prone themselves to transmit.