Occurrence: Mainly southern US states and in third world countries (multi-age farms). Species affected: Chickens in cages.
Age affected: 5-30 weeks.
Causes: Gram negative, non-motile bacterium- Hemophilus gallinarum.
Effects: The organism gives off a strong odour of rotten eggs. Symptoms include watery eyes, facial oedema, diarrhoea, anorexia, and there may be a high cull rate (20%). Nasal discharge, swollen infraorbital sinus, laboured breathing, drop in egg production and poor shell quality can also occur.
Special note: It is found more commonly in developing countries on multi-age farms)and backyard flocks. Several serotypes (A-C) make successful vaccination difficult.
Infectious coryza is more common in tropical humid areas and where multi-age pullet farms are kept. Coryza means head cold. The causative agent, Hemophilus gallinarum is a gram-negative, polar-staining, non- motile bacterium, and appears as short rods or coccobacilli.
Mode of transmission
Strong odour (rotten eggs) given off by the organism. Watery eyes, facial oedema, diarrhoea, anorexia, and high cull rate (20%) may be evident. Nasal discharge, swollen infraorbital sinus, laboured breathing, drop in egg production and shell quality can occur.
Oral or tracheal lesions, catarrhal inflammation of nasal passages and sinuses may be seen. Congested lungs, facial swelling, swollen wattles, pneumonia, air sacculitis and conjunctivitis may be evident.
Respiratory signs, odour and isolation of organisms are important. The organism is a polar-staining, facultative anaerobic gram-negative rod. Brain heart infusion and NAD-yields tiny dew- drop colonies. Serologic tests include agar gel precipitin and haemagglutination-inhibition. It simulates many respiratory problems, fowl pox (FP), vitamin A deficiency, fowl cholera (FC), and mycoplasma infections.
Treatment & control
Both live and killed vaccines are often given to pullet flocks. Antibiotics in the feed or water.