Infectious Coryza (Avibacterium paragallinarum): Facial Swelling Guide
Veterinary reference covering Avibacterium paragallinarum Serogroups A, B, C, foul facial catarrh, egg drops, and bacterin prophylaxis.
Scientific Overview
Infectious Coryza is an acute bacterial respiratory disease of chickens caused by Avibacterium paragallinarum. It is characterized by marked facial swelling (infraorbital sinusitis), purulent conjunctivitis, foul-smelling catarrhal nasal discharge, and severe egg production drops (10% to 40%) in commercial laying hens.
Etiology & Serogrouping (A, B, C)
Infectious Coryza is defined as an acute bacterial upper respiratory infection of chickens caused by Avibacterium paragallinarum (formerly Haemophilus paragallinarum), a Gram-negative fastidious bacterium requiring V-factor (NADH) for growth.
Isolates are classified into Page Serogroups A, B, and C. Cross-protection between serogroups is absent, requiring trivalent bacterin vaccines for complete protection.
Clinical Signs & Pathognomonic Lesions
Clinical presentation in affected layer flocks:
- Facial Edema: Acute swelling of the periocular tissues, wattles, and infraorbital sinuses, often closing one or both eyes.
- Foul Nasal Discharge: Thick, purulent, foul-smelling catarrhal nasal discharge that dries into crusts around nostrils.
- Production Loss: Laying flocks experience a sharp 10–40% drop in egg yield. Track lay rates in our Hen-Day Production Calculator.
Antibiotic Therapy & Trivalent Bacterin Vaccination
Water-soluble Erythromycin, Sulfamethoxazole-Trimethoprim, or Oxytetracycline reduces clinical severity, but treated birds remain chronic asymptomatic carriers. Prevention relies on administering trivalent inactivated Coryza bacterins (Serogroups A, B, C) twice during pullet rearing (at 10 and 16 weeks of age).