Infectious coryza is a specific bacterial infection caused by Avibacterium paragallinarum that affects poultry, including chickens. It is characterized by respiratory symptoms such as nasal discharge, sneezing, and swelling around the eyes and face. The disease can cause poor growth in young birds and a significant decrease in egg-laying in mature birds.
It is commonly observed during a flock’s peak egg-laying phase and can occur following stressful events like relocation. The bacteria that cause infectious coryza is prevalent in certain regions of the country but can appear in any area where poultry is raised.
Infectious Coryza Management in Chicken
Causes of Infectious Coryza Disease
Infectious coryza is caused by Avibacterium paragallinarum (formerly Haemophilus paragallinarum). The disease is more severe in older birds and can be transmitted through contaminated drinking water or airborne means over a short distance. Direct contact can also lead to lateral transmission of the disease.
Intercurrent infections with microorganisms such as infectious bronchitis virus, Mycoplasma gallisepticum, Escherichia coli, or Pasteurella spp., as well as unfavorable environmental conditions, act as the primary source of the disease in clinically affected and carrier birds. These factors can aggravate and prolong chronic respiratory disease.
Disease Cycle of Infectious Coryza
The disease cycle of infectious coryza involves carriers or chronically ill birds serving as the reservoir of infection for the causative bacteria, Avibacterium paragallinarum. Chickens of all ages are susceptible, with older birds being more susceptible. The incubation period is typically 1-3 days, and the disease duration is 2-3 weeks, which may be longer in the presence of concurrent diseases such as mycoplasmosis. This disease’s transmission occurs through direct contact, airborne droplets, and contamination of drinking water. Eggs do not transmit the disease.
Symptoms of Infectious Coryza Disease
- Infectious coryza is characterized by rapid spread, high morbidity, and low mortality in flocks on deep litter management. The disease primarily affects chickens, and the first typical symptoms include sneezing, mucous-like discharge from the nose and eyes, and swelling on the face (facial edema).
- In severe cases, conjunctivitis with closed eyes, swollen wattles, and difficulty breathing can occur. Feed and water consumption is usually decreased, leading to a drop in egg production.
- Catarrhal to fibrino-purulent inflammation of the nasal passages, infraorbital sinus, and conjunctivae is typical of gross lesions.
- The sinus exudates may become consolidated and yellowish as the disease progresses or other pathogens become involved. Face and subcutaneous wattle edema are prominent.
- The upper trachea may be involved, but only in chronically complicated cases are the lungs and air sacs affected. Lethargy, depression, and stunted growth are other symptoms of infectious coryza.
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Diagnosis of Infectious Coryza in Chicken
- The diagnosis of infectious coryza in chickens can be made by isolating a gram-negative, catalase-negative organism from infected chickens. Bacterial culture and PCR assay are commonly used methods for diagnosis.
- PCR testing provides more accurate results than bacterial culture, and a real-time version of the PCR assay is available.<