Infectious coryza is a highly contagious respiratory disease of chickens caused by the bacterium Avibacterium paragallinarum. The disease affects chickens of all ages and causes facial swelling, nasal and ocular discharge, sneezing, and decreased egg production. It spreads rapidly through direct contact and contaminated air/water. Clinical signs include sinusitis, conjunctivitis, and airsacculitis. Diagnosis involves isolating the bacterium and using tests like PCR and haemagglutination inhibition. Treatment involves antibiotics like streptomycin and lincomycin. Control relies on vaccination of replacement birds and sound biosecurity to prevent introduction and spread of the disease on farms.
2. Introduction
• World wide disease of chickens
• Reported in quails and pheasants too
• USA : pullets, layers and broilers
• Pakistan: 3 weeks old chicks are affected
4. Epidemiology
• Ill birds: reservoirs
• All ages of chicken are susceptible
• Incubation period:1-3 days
• Disease course:2-3weeks
• Mortality 20%
5. Transmission
• Direct contact, airborne droplets, and
contamination of drinking water.
• Egg transmission does not occur.
6. Clinical findings
• Facial swelling.
• Infra orbital sinusitis
• Oedema of face, around eyes
• Oedema of wattles and intermadibular space in male birds
• Purulent ocular and nasal discharge
• Sneezing
• Dyspnoea
• Loss in condition
• Drop in egg production of 10-40%
• Inappetance
• Depression
• Diarrhoea
17. Histopathology
The histopathologic response of respiratory
organs consists of disintegration and
hyperplasia of mucosal and glandular epithelia
and oedema with infiltration of heterophils,
macrophages, and mast cells.
18. Diagnosis
• Isolation of a gram-negative bacterium.
• Catalase test
• Polymerase Chain Reaction
• Haemagglutination-inhibition (best)
19. Differential diagnosis
• Mycoplasmosis: Chronic respiratory disease:
no involvement of infraorbital sinuses, in
turkeys: infra orbital sinuses are involved’
• Infectious laryngotracheitis: no involvement of
infraorbital sinuses
• Newcastle disease: nervous signs
• Fowl cholera: no respiratory signs
• Infectious Bronchitis: caseous plug at
bifurcation of bronchi
21. Control
• Sound management and isolation.
• Replacements should be raised on the same farm or
obtained from clean flocks.
• If replacement pullets are to be placed on a farm that
has a history of infectious coryza, bacterins are
available to help prevent and control the disease.
• Vaccination should be completed 4 weeks before
infectious coryza usually breaks out on the individual
farm.
• Controlled exposure to live organisms also has been
used to immunize layers in endemic areas.