Identity

An acute, highly contagious viral disease caused by a single-stranded RNA Gammacoronavirus. It targets the respiratory, renal, and reproductive systems, causing severe respiratory disease, renal pathology (urolithiasis), watery egg whites, and a permanent drop in egg production.

Overview

Infectious Bronchitis (IBV) is a high-priority viral pathogen globally distributed and paramount to broiler and layer industries. The virus replicates in ciliated epithelial cells of the trachea causing deciliation, while variant strains are highly nephrotropic or target the oviduct. It causes watery egg whites and significant drops in egg production (up to 50%). Prevention relies on managing optimal air exchange to reduce environmental ammonia (which exacerbates ciliary damage) and administering specific live attenuated or inactivated vaccines (e.g., Mass-type H120, ND+IB+EDS Killed). IBV mucosal damage strongly predisposes flocks to secondary colisepticemia (APEC).

Structured Facts

Classification

Viral > Infectious Pathogen

Epidemiology

• Severity: High
• Affected Species: Poultry (Layers and young chicks highly impacted)
• Affected Age: All age classes; chicks < 3 weeks at highest risk of mortality and permanent damage
• Transmission: Extremely rapid horizontal spread via airborne aerosols, direct contact, and mechanical transmission
• Mortality: < 5% (uncomplicated), up to 30% (nephrotropic strains in young chicks)
• Morbidity: Approaches 100% in naive populations
• Economic Importance: High

Clinical Signs

• Early/Intermediate: Tracheal rales, coughing, sneezing, nasal discharge, wet eyes, severe depression. Nephrotropic: severe dehydration, increased water consumption (polydipsia)
• Advanced: Drop in egg production (up to 50%); thin-shelled, misshapen, or shell-less eggs with watery, thin albumen. Targets respiratory, renal, and urogenital systems.
• Postmortem Findings: Catarrhal tracheitis, lung congestion, serous/caseous exudate in air sacs. Nephrotropic: swollen pale kidneys with urate deposits. Layers: cystic right oviduct.

Diagnosis

• Field Diagnosis: Respiratory signs paired with specific eggshell/albumen defects and polydipsia.
• Laboratory Tests: RT-PCR targeting S1 gene, sequencing for serotype, virus isolation in embryonated eggs (embryo dwarfing/curling), ELISA
• Differential Diagnosis: Newcastle Disease, Infectious Laryngotracheitis, Mycoplasmosis

Treatment

• Medicines: None exist

Prevention

• Vaccination: IB H120 (Spray / Intraocular drop) at day-old; ND+IB+EDS Killed (Subcutaneous / Intramuscular injection)
• Biosecurity: Standard biosecurity protocols
• Farm Management: Maintain optimal air exchange to reduce environmental ammonia levels

Quantitative Data

• Morbidity Rate: ~100%
• Mortality Rate: < 5% (uncomplicated); up to 30% (nephrotropic)
• Egg Production Drop: Up to 50%

Relationships

• Vaccines: IB H120, ND+IB+EDS Killed
• Medicines: None
• Synergistic/Predisposing Factors: Ammonia Toxicity (exacerbates ciliary damage), Escherichia coli (Colibacillosis)