Infectious Coryza

Important note: Haemophilus paragallinarum (reclassified as Avibacterium paragallinarum) is a pathogen of poultry, not plants. It is the causative agent of Infectious Coryza, a severe respiratory disease affecting chickens worldwide.

The organism is a fastidious, Gram-negative bacterium. It primarily infects the upper respiratory tract of birds. As it is not an agricultural plant pest, its management is strictly within the domain of veterinary medicine and avian pathology.

The primary species affected is the domestic chicken. The bacteria colonize the nasal passages, infraorbital sinuses, and the conjunctiva. Transmission occurs via direct contact, contaminated water, or airborne droplets within close proximity in a poultry house.

Typical clinical signs and symptoms of the disease include:

• facial swelling and edema of the wattles;
• nasal discharge which may become thick and foul-smelling;
• conjunctivitis and watery eyes;
• respiratory distress, characterized by rales and sneezing;
• significant drop in egg production and weight loss.

Control strategies involve strict biosecurity protocols, including the depopulation of infected flocks, thorough cleaning, and disinfection of facilities. Vaccination is the most effective preventative measure. Antibiotic therapy may be used during an outbreak to reduce mortality, but vaccination remains the gold standard for maintaining flock health and preventing the recurrence of the disease.