Coryza
Occurrence: Worldwide, but more common in tropical areas of the world and in farms with multiage pullets. Coryza means head cold.
Age of bird: Mostly 15‑30 weeks, but has been seen in broiler age birds.
Species affected: Only chickens.
Cause: Haemophilus paragallinarum is a gram‑negative, polar‑staining, non‑motile bacterium, and appears as short rods or coccobacilli.
Causes
A chronic disease caused by Haemophilus paragallinarum is a gram‑negative, polar‑staining, non‑motile bacterium, and appears as short rods or coccobacilli. Strong odor (rotten eggs) given off by the organism.
Mode of transmission
Clinical signs
Watery eyes, facial edema, diarrhea, lowered weight gain, anorexia, and high cull rate (20%) may be evident. Nasal discharge, swollen infraorbital sinus, labored breathing, drop in egg production and shell quality can occur.
Postmortem lesions
Oral or tracheal lesions, catarrhal inflammation of nasal passages and sinuses may be seen. Congested lungs, facial swelling, swollen wattles, pneumonia, airsacculitis, and conjunctivitis may be evident.
Diagnosis
Respiratory signs, odor and isolation of organisms are important. Serologic tests include agar gel precipitin and hemagglutination‑inhibition. It simulates many respiratory problems, fowl pox (FP), vitamin A deficiency, fowl cholera (FC), and mycoplasma infections.
Prevention
Bacterin (containing serogroups A,B,C) at 10‑12 and 16‑18 weeks and one age per farm can help prevent the disease. Destroy all clinically ill birds to contain spread of the organism.
Treatment
A number of antibiotics can be used in the feed or water.
Coryza insights
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Old bird diseases occur more among free-range hens
Over the last two decades old bird
diseases, such as Coryza, Blackhead and Pasteurelle multocida increasingly reared their ugly heads among
free-range hens. These diseases barely occurred when laying hens were kept in cages.
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