Infectious coryza is a bacterial disease that affects the respiratory system of chickens. It is characterized by inflammation of the area below the eye, nasal discharge, sneezing, and facial swelling. The disease can cause decreased activity in chickens and can affect egg production.

The disease is caused by the bacterium Avibacterium paragallinarum, which can be spread from bird to bird through direct contact, airborne droplets, and contaminated feed or drinking water. The incubation period is one to three days, and the disease can last for two to three weeks.

Diagnosis of infectious coryza is by isolation of bacteria from chickens suspected to have a history of coryza and clinical findings from infected chickens. Polymerase chain reaction testing is a reliable means of diagnosis of the disease. Differential diagnoses for an acute upper respiratory infection of chickens include fowl cholera, mycoplasmosis, ornithobacteriosis, swollen head syndrome, and avitaminosis A.

Treatment of infectious coryza consists of using antibiotics such as erythromycin, dihydrostreptomycin, streptomycin, sulfonamides, tylosin, and fluoroquinolones. Prevention is through the use of stock coryza-free birds, all-in/all-out flow of animals as part of sound farm management and biosecurity practices, and vaccination of chicks in areas with high disease occurrence.