Infectious coryza, caused by the bacterium Avibacterium
paragallinarum (previously Haemophilus paragallinarum) , is a
disease of poultry with the first serious outbreak in South
Africa in 1968. Soon afterwards the disease spread to most large
poultry production sites and established itself as the most
common bacterial infection in layers. One of the main reasons
for the very successful spread of A. paragallinarum is the fact
that the chickens that recover from the infection become
carriers and these chickens are often sold at point-of-lay, thus
introducing the infection to new, clean sites. This disease
causes severe reduction in egg production and is thus of
significant financial importance to the poultry industry.
Infectious coryza causes an upper respiratory tract infection in
poultry. This disease usually only shows mild clinical symptoms,
but causes marked economic losses in many countries where egg
production of between 10-40% may occur. The most prominent
features of the disease include nasal discharge