Infectious coryza
A highly infectious bacterial disease of chickens caused by Hemop hilus paragallinarum, is characterized by catarrhal inflammation of the upper respiratory tract, especially nasal mucosa and sinuses. It is generally accompanied by other respiratory viral or bacterial infections that may act as predisposing factors and may perpetuate the condition. There is high morbidity but low mortality if not accompanied by secondary infections. The route of infection is conjunctival or nasal with rapid onset of disease over a 3-4 days period. The infection may linger on in a flock for 1-2 weeks and recovered birds may become carriers. The bacterium is susceptible to environmental factors and is easily killed by heat, drying and disinfectants.
Symptoms and lesions: The most common symptoms seen are inappetance, sneezing, coughing, swelling of face, combs and wattles, ocular and nasal discharge that may become purulent. Egg production may drop to significant level. The post-mortem lesions depend upon involvement of secondary infections but mostly restrict to upper respiratory tract that include catarrhal inflammation of nasal passages and sinuses, sticky eyes, sometimes conjunctivitis, and tracheitis.
Diagnosis: A presumptive diagnosis may be made on clinical signs, lesions and isolation and identification of the bacteria in a Gram-stained smear from sinus.
Prevention and control: An all-in/all-out production system should be the farm policy. The overall health management and balanced nutrition would keep the infection away from the farm. Vaccines are used in areas of high incidence.