Diseases: Infectious Coryza

Introduction

• An acute respiratory disease of chickens
• Caused by a bacterium Haemophilus paragallinarum

 

Clinical Signs

• All ages affected but less severe in young birds
• Nasal discharge, swelling of the face, and conjunctivitis
• Swollen wattles
• Unusual respiratory sounds may be head
• Decreased egg production
• Diarrhoea may be observed

 

Post Mortem Lesions

• Watery discharges in the nasal passages and sinuses
• Conjunctivitis
• Swelling under the skin

 

Diagnosis

• Produces similar signs to chronic respiratory disease
• Confirm diagnosis by isolation of the organism

 

Samples

• Swabs from sinuses
• Swabs of exudate in trachea and air sacs

 

Transmission

• Highly infectious – in secretions from nose and mouth
• Airborne spread is the main route of infection
• Spreads in contaminated water
• Chronically infected or healthy carrier birds are the main reservoir of infection

 

Treatment

• Various sulphonamides and antibiotics are useful in alleviating the severity of the disease but relapse often occurs after treatment is discontinued.  N.B. The withdrawal period is a minimum of 10 days before slaughter for food.

 

Prevention and Control

• Management – care with the introduction of new birds as recovered carrier birds are the main source of infection.
• Bacteria are destroyed rapidly in the environment
• Chicken houses should be left vacant for 2 to 3 weeks before restocking