Mycoplasma respiratory infection is a chronic and often persistent respiratory disease in birds caused by various species of Mycoplasma, which are the smallest self-replicating bacteria known. These unique organisms lack a cell wall, which distinguishes them from typical bacteria and has implications for both their biology and treatment. Mycoplasma infections of the respiratory tract can affect both the upper and lower respiratory system, causing sinusitis, tracheitis, pneumonia, and air sacculitis. The infection is common in domestic poultry, game birds, and various pet bird species, though certain Mycoplasma species show preferences for particular host groups. Mycoplasmosis represents an important cause of chronic respiratory disease in avian populations and can be challenging to fully eradicate once established.
The Mycoplasma organisms that affect birds include several species with different host ranges and clinical presentations. Mycoplasma gallisepticum is one of the most important avian pathogens, primarily affecting chickens and turkeys but also causing disease in pet birds, particularly finches where it causes a distinctive conjunctivitis. Mycoplasma synoviae affects poultry and can spread to other species. Various Mycoplasma species have been isolated from psittacine birds with respiratory disease, though their role as primary pathogens versus secondary invaders is sometimes debated. Transmission occurs through direct contact with infected birds, aerosol transmission of respiratory secretions, and vertical transmission from infected parents to offspring through eggs.
The impact of mycoplasma respiratory infection on bird health varies from subclinical carrier states to significant chronic disease. Birds may carry Mycoplasma organisms without showing obvious signs, shedding bacteria and infecting other birds while appearing healthy. When clinical disease develops, it typically manifests as chronic respiratory signs including nasal discharge, sneezing, and respiratory sounds that may persist for weeks to months. The infection often causes swelling of sinuses, which is particularly visible around the eyes and infraorbital area. Secondary bacterial infections frequently complicate mycoplasma infection, worsening clinical signs. The chronic nature of the disease can lead to reduced quality of life, poor growth in young birds, and decreased production in breeding situations.
Mycoplasma respiratory infection is treatable with appropriate antibiotics, though treatment can be challenging and recurrence is common. Because Mycoplasma organisms lack a cell wall, antibiotics that target cell wall synthesis such as penicillins are ineffective. Effective antibiotics include tetracyclines, fluoroquinolones, and macrolides. Treatment must be continued for extended periods to suppress infection, and complete elimination of the organism may not be achieved. Prevention through biosecurity measures and testing is important for protecting collections and breeding programs. Any bird with chronic respiratory disease, particularly those with sinus involvement, should be evaluated for Mycoplasma infection as part of a comprehensive diagnostic workup.
