The bacterium causing this disease is Hemophilus paragallinarum
The disease spreads from bird to bird and flock to flock by contact and airborne-infected dust particles and also via the drinking water. Spread by equipment and personnel has also been reported. The incubation period varies from 1 to 3 days
Chickens appear to be the only natural hosts of H. paragallinarum
The main signs of the disease are inflammation of eyes and nose with foul-smelling discharges, conjunctivitis, sneezing and facial swellings. Feed and water intake is reduced, leading to loss of weight. Egg production in laying birds drops significantly.
Mortality varies with the virulence of the infection but it is generally low.
A field infection produces similar symptoms as Chronic Respiratory Disease (CRD), and diagnosis is difficult to establish. The most certain diagnosis may be obtained by the isolation of the organism from the sinus or airsac exudates from affected birds. This procedure must be carried out in the laboratory
Treatment and control
Treatment with antibiotics can be given to subdue clinical infection. Eradication and prevention are the most desirable means of control of Coryza. Vaccines have been developed, but are only used in areas where the disease is endemic and cannot be eradicated.