Identity

A high-priority bacterial infectious disease caused by wall-less Mollicutes. MG targets the respiratory epithelium causing Chronic Respiratory Disease, while MS targets synovial membranes causing joint swelling. Both severely reduce performance and interact synergistically with viral vaccines to cause high mortality.

Overview

Avian Mycoplasmosis (MG/MS) affects commercial poultry globally. These wall-less bacteria attach to host cells via specific surface adhesins, leading to deciliation and inflammation. MG causes respiratory disease and severe airsacculitis, while MS causes suppurative synovitis. They are transmitted both vertically (via the egg) and horizontally. A critical aspect of mycoplasmosis is its synergistic interaction with live respiratory vaccines (NDV/IBV), which vastly exacerbates mortality. DAHD guidelines require serological monitoring to ensure breeder flocks remain free. Treatment utilizes macrolides (Tylosin) or pleuromutilins (Tiamulin) with strict withdrawal periods.

Structured Facts

Classification

Bacterial > Infectious Pathogen

Epidemiology

• Prevalence in India: High commercial importance; managed via DAHD monitoring
• Severity: High
• Affected Species: Poultry
• Affected Age: All ages; clinical signs pronounced in growing birds and layers
• Transmission: Vertical (through the egg) and Horizontal (airborne dust, aerosols, fomites)
• Mortality: < 5% (uncomplicated); significant when co-infected with viruses
• Morbidity: 90% to 100%
• Economic Importance: High (chronic signs, poor feed efficiency, carcass condemnation)

Clinical Signs

• Early/Intermediate: MG: Tracheal rales, coughing, sneezing, nasal discharge, conjunctivitis, drop in lay. MS: Progressive lameness.
• Advanced: MG: Chronic respiratory disease. MS: Swollen hock joints/footpads, breast blisters. Targets Respiratory and Synovial systems.
• Postmortem Findings: MG: Catarrhal tracheitis, severe airsacculitis (yellow caseous exudate). MS: Cream-colored viscid/caseous exudate in joint cavities/tendon sheaths.

Diagnosis

• Field Diagnosis: Chronic respiratory signs or swollen hocks
• Laboratory Tests: Serology (Serum Plate Agglutination, ELISA, HI test), PCR, Isolation on Frey's medium ("fried-egg" microcolonies)
• Differential Diagnosis: Infectious Bronchitis, Infectious Coryza, Colibacillosis

Treatment

• Immediate Actions: Ensure breeder freedom
• Medicines: Tylosin Phosphate (Macrolide), Tiamulin Hydrogen Fumarate (Pleuromutilin), Tetracyclines (via drinking water/feed per SVTG)
• Withdrawal: Tylosin Phosphate: 5 Days; Tiamulin: 3 Days
• Veterinary Intervention: Guided by SVTG protocols

Prevention

• Vaccination: Not specified for routine control; strict synergy warnings against live viral vaccines
• Biosecurity: Mitigated by standard Biosecurity Protocols
• Farm Management: Maintain Mycoplasma-free breeder flocks via serological monitoring

Quantitative Data

• Morbidity Rate: 90% to 100%
• Mortality Rate: < 5% (Uncomplicated)
• Tylosin Phosphate Withdrawal: 5 Days
• Tiamulin Withdrawal: 3 Days

Relationships

• Vaccines: None specific for MG/MS, but highly synergistic with live NDV/IBV vaccines
• Medicines: Tylosin Phosphate, Tiamulin Hydrogen Fumarate, Tetracyclines
• Biosecurity: Biosecurity Protocols
• Synergistic Relationships: Newcastle Disease Virus, Infectious Bronchitis Virus