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
