Infectious Coryza and Related Bacterial Infections

Infectious coryza is an acute respiratory disease of chickens caused by the bacterium known as Avibacterium paragallinarum, once known as Haemophilus paragallinarum and Haemophilus gallinarum. The greatest economic losses associated with infectious coryza result from poor growth performance in growing birds and marked reduction in egg production in layers. It is generally accepted that Av. paragallinarum is a primary pathogen while the other genus members are either opportunistic pathogens (Av. endocarditidis, Av. gallinarum) or not recognized as pathogens (Av. avium, Av. volantium). Infectious coryza occurs wherever chickens are raised and is a common problem in the intensive chicken industry. The disease also has been reported in other, less intensive situations. The chicken is the natural host for Av. paragallinarum. There are reports that the village chickens of Africa sand Asia are as susceptible to infectious coryza as normal commercial breeds.