Infectious coryza

• It is usually acute and sometimes chronic, disease of chicken, occasionally pleasant and guinea fowl..

• Characterized by catarrhal inflammation of URT, specially nasal and sinus mucosae.
• It is found worldwide.
• Also known as fowl coryza
• The disease was named Infectious coryza because it was infectious and affected primarily nasal passage ( nasal discharge, sneezing , swelling of face under eye ).
• All ages are susceptible but occurs most often in adult birds ( layers ) ; so mul;ti- age farms are more susceptible.
• Morbidity is high but mortality is low ( about 20 %)

  Etiology :

           Avibacterium paragallinarum (Haemophilus paragallinarum )

   [gram negative, pleomorphic, non-motile , catalase -ve ;

         microaerophilic rod : requires NAD (v-factor) for in vitro growth ]

• Bacteria can survive 2-3 days outside the bird.

  Transmission :

• Direct contact , airborne droplets, and contamination of drinking water.
• Egg transmission does not occur.
• Carrier can transmit via exudate and by direct contact
• Ill or sick birds and recovered birds are carrier of disease ( one of the imp source of disease )

• Route of infection :

                     Conjunctival route , nasal route 

 Pathogenesis :

     Entry of bacteria through route of inhalation

                              🠋

    Bacteria binds to ciliated mucosa of URT

                              🠋

    Bacteria contain capsule and HA which help them to lyse the host cell

                              🠋

                      Colonization

                              🠋

          Bacteria release endotoxin

                              🠋

                   Pathological lesions

  Clinical signs :

• Facial swelling
• Infraorbital sinusitis
• Edema of face around eyes
• Edema of wattle and intermandibular space in male birds
• Purulent ocular and nasal discharge
• Sneezing
• Dyspnoea
• Loss in condition
• Anorexia
• Drop in egg production
• Diarrhoea
• Decrease in growth and development

Postmortem finding :

• In acute; infraorbital sinus ; there is a copious , tenacious , grayish , semifluid exudate .
• Chronic; sinus exudate 🠚  consolidated and turn yellowish
• Other lesions:
• Conjunctivitis
• Eye-lid adherence
• Caseous yellowish material in sinuses
• Tracheitis and bronchitis
• Air sacculitis
• When layers are infected ;  there is peritonitis ; due to deposited egg in peritoneal cavity
• Soft shell eggs and egg with hematomas are often seen in ovary

Microscopic :

• Histopathologic response of respiratory organs consists of disintegration and hyperplasia of mucosal and granular epithelia and edema with infiltration of heterophils, macrophages and mast cells.
• Fibrinopurulent cellulitis
• Air sacs: edema thickening, mesothelial hyperplasia , fibrin deposition

Diagnosis :

• History
• Clinical sign and lesions
• Isolation and identification of gram -ve bacteria (bipolar filamentous or coccoid organism )
• Biochemical test :

                 Catalase test

• PCR
• Serological test : hema agglutination inhibition test ( HI test ) – best one

    DDx :

1. Mycoplasmosis : chronic respiratory disease

                          No involvement of infraorbital sinuses ( except turkey )

1. Infectious laryngotracheitis :     No involvement of infraorbital sinuses
2. Newcastle disease : nervous signs
3. Fowl cholera : no respiratory signs
4. Infectious bronchitis :    caseous plug at bifurcation of bronchi
5. Vitamin A deficiency